Merge enhancements from trunk.

FossilOrigin-Name: 66fe06832614010d3156d7b21a760af9957018cc

38 files changed, 1048 insertions, 538 deletions

diff --git a/src/analyze.c b/src/analyze.c
index 69d4b659c..ad752d2c0 100644
--- a/src/analyze.c
+++ b/src/analyze.c
@@ -1186,6 +1186,7 @@ static void analyzeOneTable(
       regKey = sqlite3GetTempRange(pParse, pPk->nKeyCol);
       for(j=0; j<pPk->nKeyCol; j++){
         k = sqlite3ColumnOfIndex(pIdx, pPk->aiColumn[j]);
+        assert( k>=0 && k<pTab->nCol );
         sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, regKey+j);
         VdbeComment((v, "%s", pTab->aCol[pPk->aiColumn[j]].zName));
       }
@@ -1235,12 +1236,10 @@ static void analyzeOneTable(
       ** be taken */
       VdbeCoverageNeverTaken(v);
 #ifdef SQLITE_ENABLE_STAT3
-      sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, 
-                                      pIdx->aiColumn[0], regSample);
+      sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iTabCur, 0, regSample);
 #else
       for(i=0; i<nCol; i++){
-        i16 iCol = pIdx->aiColumn[i];
-        sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur, iCol, regCol+i);
+        sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iTabCur, i, regCol+i);
       }
       sqlite3VdbeAddOp3(v, OP_MakeRecord, regCol, nCol, regSample);
 #endif
diff --git a/src/btree.c b/src/btree.c
index de6b089a3..b8aef7bd5 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -591,26 +591,25 @@ static void btreeReleaseAllCursorPages(BtCursor *pCur){
   pCur->iPage = -1;
 }
 
-
 /*
-** Save the current cursor position in the variables BtCursor.nKey 
-** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
+** The cursor passed as the only argument must point to a valid entry
+** when this function is called (i.e. have eState==CURSOR_VALID). This
+** function saves the current cursor key in variables pCur->nKey and
+** pCur->pKey. SQLITE_OK is returned if successful or an SQLite error 
+** code otherwise.
 **
-** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
-** prior to calling this routine.  
+** If the cursor is open on an intkey table, then the integer key
+** (the rowid) is stored in pCur->nKey and pCur->pKey is left set to
+** NULL. If the cursor is open on a non-intkey table, then pCur->pKey is 
+** set to point to a malloced buffer pCur->nKey bytes in size containing 
+** the key.
 */
-static int saveCursorPosition(BtCursor *pCur){
+static int saveCursorKey(BtCursor *pCur){
   int rc;
-
-  assert( CURSOR_VALID==pCur->eState || CURSOR_SKIPNEXT==pCur->eState );
+  assert( CURSOR_VALID==pCur->eState );
   assert( 0==pCur->pKey );
   assert( cursorHoldsMutex(pCur) );
 
-  if( pCur->eState==CURSOR_SKIPNEXT ){
-    pCur->eState = CURSOR_VALID;
-  }else{
-    pCur->skipNext = 0;
-  }
   rc = sqlite3BtreeKeySize(pCur, &pCur->nKey);
   assert( rc==SQLITE_OK );  /* KeySize() cannot fail */
 
@@ -618,8 +617,7 @@ static int saveCursorPosition(BtCursor *pCur){
   ** stores the integer key in pCur->nKey. In this case this value is
   ** all that is required. Otherwise, if pCur is not open on an intKey
   ** table, then malloc space for and store the pCur->nKey bytes of key 
-  ** data.
-  */
+  ** data.  */
   if( 0==pCur->curIntKey ){
     void *pKey = sqlite3Malloc( pCur->nKey );
     if( pKey ){
@@ -634,7 +632,30 @@ static int saveCursorPosition(BtCursor *pCur){
     }
   }
   assert( !pCur->curIntKey || !pCur->pKey );
+  return rc;
+}
+
+/*
+** Save the current cursor position in the variables BtCursor.nKey 
+** and BtCursor.pKey. The cursor's state is set to CURSOR_REQUIRESEEK.
+**
+** The caller must ensure that the cursor is valid (has eState==CURSOR_VALID)
+** prior to calling this routine.  
+*/
+static int saveCursorPosition(BtCursor *pCur){
+  int rc;
 
+  assert( CURSOR_VALID==pCur->eState || CURSOR_SKIPNEXT==pCur->eState );
+  assert( 0==pCur->pKey );
+  assert( cursorHoldsMutex(pCur) );
+
+  if( pCur->eState==CURSOR_SKIPNEXT ){
+    pCur->eState = CURSOR_VALID;
+  }else{
+    pCur->skipNext = 0;
+  }
+
+  rc = saveCursorKey(pCur);
   if( rc==SQLITE_OK ){
     btreeReleaseAllCursorPages(pCur);
     pCur->eState = CURSOR_REQUIRESEEK;
@@ -8047,10 +8068,15 @@ end_insert:
 }
 
 /*
-** Delete the entry that the cursor is pointing to.  The cursor
-** is left pointing at an arbitrary location.
+** Delete the entry that the cursor is pointing to. 
+**
+** If the second parameter is zero, then the cursor is left pointing at an
+** arbitrary location after the delete. If it is non-zero, then the cursor 
+** is left in a state such that the next call to BtreeNext() or BtreePrev()
+** moves it to the same row as it would if the call to BtreeDelete() had
+** been omitted.
 */
-int sqlite3BtreeDelete(BtCursor *pCur){
+int sqlite3BtreeDelete(BtCursor *pCur, int bPreserve){
   Btree *p = pCur->pBtree;
   BtShared *pBt = p->pBt;              
   int rc;                              /* Return code */
@@ -8059,6 +8085,7 @@ int sqlite3BtreeDelete(BtCursor *pCur){
   int iCellIdx;                        /* Index of cell to delete */
   int iCellDepth;                      /* Depth of node containing pCell */ 
   u16 szCell;                          /* Size of the cell being deleted */
+  int bSkipnext = 0;                   /* Leaf cursor in SKIPNEXT state */
 
   assert( cursorHoldsMutex(pCur) );
   assert( pBt->inTransaction==TRANS_WRITE );
@@ -8088,10 +8115,7 @@ int sqlite3BtreeDelete(BtCursor *pCur){
   }
 
   /* Save the positions of any other cursors open on this table before
-  ** making any modifications. Make the page containing the entry to be 
-  ** deleted writable. Then free any overflow pages associated with the 
-  ** entry and finally remove the cell itself from within the page.  
-  */
+  ** making any modifications.  */
   if( pCur->curFlags & BTCF_Multiple ){
     rc = saveAllCursors(pBt, pCur->pgnoRoot, pCur);
     if( rc ) return rc;
@@ -8103,6 +8127,31 @@ int sqlite3BtreeDelete(BtCursor *pCur){
     invalidateIncrblobCursors(p, pCur->info.nKey, 0);
   }
 
+  /* If the bPreserve flag is set to true, then the cursor position must
+  ** be preserved following this delete operation. If the current delete
+  ** will cause a b-tree rebalance, then this is done by saving the cursor
+  ** key and leaving the cursor in CURSOR_REQUIRESEEK state before 
+  ** returning. 
+  **
+  ** Or, if the current delete will not cause a rebalance, then the cursor
+  ** will be left in CURSOR_SKIPNEXT state pointing to the entry immediately
+  ** before or after the deleted entry. In this case set bSkipnext to true.  */
+  if( bPreserve ){
+    if( !pPage->leaf 
+     || (pPage->nFree+cellSizePtr(pPage,pCell)+2)>(int)(pBt->usableSize*2/3)
+    ){
+      /* A b-tree rebalance will be required after deleting this entry.
+      ** Save the cursor key.  */
+      rc = saveCursorKey(pCur);
+      if( rc ) return rc;
+    }else{
+      bSkipnext = 1;
+    }
+  }
+
+  /* Make the page containing the entry to be deleted writable. Then free any
+  ** overflow pages associated with the entry and finally remove the cell
+  ** itself from within the page.  */
   rc = sqlite3PagerWrite(pPage->pDbPage);
   if( rc ) return rc;
   rc = clearCell(pPage, pCell, &szCell);
@@ -8156,7 +8205,22 @@ int sqlite3BtreeDelete(BtCursor *pCur){
   }
 
   if( rc==SQLITE_OK ){
-    moveToRoot(pCur);
+    if( bSkipnext ){
+      assert( bPreserve && pCur->iPage==iCellDepth );
+      assert( pPage->nCell>0 && iCellIdx<=pPage->nCell );
+      pCur->eState = CURSOR_SKIPNEXT;
+      if( iCellIdx>=pPage->nCell ){
+        pCur->skipNext = -1;
+        pCur->aiIdx[iCellDepth] = pPage->nCell-1;
+      }else{
+        pCur->skipNext = 1;
+      }
+    }else{
+      rc = moveToRoot(pCur);
+      if( bPreserve ){
+        pCur->eState = CURSOR_REQUIRESEEK;
+      }
+    }
   }
   return rc;
 }
diff --git a/src/btree.h b/src/btree.h
index e0c9ab0ab..910abe6b8 100644
--- a/src/btree.h
+++ b/src/btree.h
@@ -222,7 +222,7 @@ int sqlite3BtreeMovetoUnpacked(
 );
 int sqlite3BtreeCursorHasMoved(BtCursor*);
 int sqlite3BtreeCursorRestore(BtCursor*, int*);
-int sqlite3BtreeDelete(BtCursor*);
+int sqlite3BtreeDelete(BtCursor*, int);
 int sqlite3BtreeInsert(BtCursor*, const void *pKey, i64 nKey,
                                   const void *pData, int nData,
                                   int nZero, int bias, int seekResult);
diff --git a/src/build.c b/src/build.c
index a5e838ccb..eee62ee15 100644
--- a/src/build.c
+++ b/src/build.c
@@ -357,12 +357,14 @@ Table *sqlite3LocateTable(
   if( p==0 ){
     const char *zMsg = isView ? "no such view" : "no such table";
 #ifndef SQLITE_OMIT_VIRTUALTABLE
-    /* If zName is the not the name of a table in the schema created using
-    ** CREATE, then check to see if it is the name of an virtual table that
-    ** can be an eponymous virtual table. */
-    Module *pMod = (Module*)sqlite3HashFind(&pParse->db->aModule, zName);
-    if( pMod && sqlite3VtabEponymousTableInit(pParse, pMod) ){
-      return pMod->pEpoTab;
+    if( sqlite3FindDbName(pParse->db, zDbase)<1 ){
+      /* If zName is the not the name of a table in the schema created using
+      ** CREATE, then check to see if it is the name of an virtual table that
+      ** can be an eponymous virtual table. */
+      Module *pMod = (Module*)sqlite3HashFind(&pParse->db->aModule, zName);
+      if( pMod && sqlite3VtabEponymousTableInit(pParse, pMod) ){
+        return pMod->pEpoTab;
+      }
     }
 #endif
     if( zDbase ){
@@ -372,7 +374,7 @@ Table *sqlite3LocateTable(
     }
     pParse->checkSchema = 1;
   }
-#if SQLITE_USER_AUTHENICATION
+#if SQLITE_USER_AUTHENTICATION
   else if( pParse->db->auth.authLevel<UAUTH_User ){
     sqlite3ErrorMsg(pParse, "user not authenticated");
     p = 0;
@@ -443,6 +445,7 @@ static void freeIndex(sqlite3 *db, Index *p){
   sqlite3DeleteIndexSamples(db, p);
 #endif
   sqlite3ExprDelete(db, p->pPartIdxWhere);
+  sqlite3ExprListDelete(db, p->aColExpr);
   sqlite3DbFree(db, p->zColAff);
   if( p->isResized ) sqlite3DbFree(db, p->azColl);
 #ifdef SQLITE_ENABLE_STAT3_OR_STAT4
@@ -983,6 +986,8 @@ void sqlite3StartTable(
     int j1;
     int fileFormat;
     int reg1, reg2, reg3;
+    /* nullRow[] is an OP_Record encoding of a row containing 5 NULLs */
+    static const char nullRow[] = { 6, 0, 0, 0, 0, 0 };
     sqlite3BeginWriteOperation(pParse, 1, iDb);
 
 #ifndef SQLITE_OMIT_VIRTUALTABLE
@@ -1027,7 +1032,7 @@ void sqlite3StartTable(
     }
     sqlite3OpenMasterTable(pParse, iDb);
     sqlite3VdbeAddOp2(v, OP_NewRowid, 0, reg1);
-    sqlite3VdbeAddOp2(v, OP_Null, 0, reg3);
+    sqlite3VdbeAddOp4(v, OP_Blob, 6, reg3, 0, nullRow, P4_STATIC);
     sqlite3VdbeAddOp3(v, OP_Insert, 0, reg3, reg1);
     sqlite3VdbeChangeP5(v, OPFLAG_APPEND);
     sqlite3VdbeAddOp0(v, OP_Close);
@@ -1309,7 +1314,8 @@ void sqlite3AddPrimaryKey(
     nTerm = pList->nExpr;
     for(i=0; i<nTerm; i++){
       Expr *pCExpr = sqlite3ExprSkipCollate(pList->a[i].pExpr);
-      if( pCExpr && pCExpr->op==TK_ID ){
+      assert( pCExpr!=0 );
+      if( pCExpr->op==TK_ID ){
         const char *zCName = pCExpr->u.zToken;
         for(iCol=0; iCol<pTab->nCol; iCol++){
           if( sqlite3StrICmp(zCName, pTab->aCol[iCol].zName)==0 ){
@@ -2849,6 +2855,30 @@ Index *sqlite3AllocateIndexObject(
 }
 
 /*
+** Backwards Compatibility Hack:
+** 
+** Historical versions of SQLite accepted strings as column names in
+** indexes and PRIMARY KEY constraints and in UNIQUE constraints.  Example:
+**
+**     CREATE TABLE xyz(a,b,c,d,e,PRIMARY KEY('a'),UNIQUE('b','c' COLLATE trim)
+**     CREATE INDEX abc ON xyz('c','d' DESC,'e' COLLATE nocase DESC);
+**
+** This is goofy.  But to preserve backwards compatibility we continue to
+** accept it.  This routine does the necessary conversion.  It converts
+** the expression given in its argument from a TK_STRING into a TK_ID
+** if the expression is just a TK_STRING with an optional COLLATE clause.
+** If the epxression is anything other than TK_STRING, the expression is
+** unchanged.
+*/
+static void sqlite3StringToId(Expr *p){
+  if( p->op==TK_STRING ){
+    p->op = TK_ID;
+  }else if( p->op==TK_COLLATE && p->pLeft->op==TK_STRING ){
+    p->pLeft->op = TK_ID;
+  }
+}
+
+/*
 ** Create a new index for an SQL table.  pName1.pName2 is the name of the index 
 ** and pTblList is the name of the table that is to be indexed.  Both will 
 ** be NULL for a primary key or an index that is created to satisfy a
@@ -2889,7 +2919,6 @@ Index *sqlite3CreateIndex(
   int iDb;             /* Index of the database that is being written */
   Token *pName = 0;    /* Unqualified name of the index to create */
   struct ExprList_item *pListItem; /* For looping over pList */
-  const Column *pTabCol;           /* A column in the table */
   int nExtra = 0;                  /* Space allocated for zExtra[] */
   int nExtraCol;                   /* Number of extra columns needed */
   char *zExtra = 0;                /* Extra space after the Index object */
@@ -3061,7 +3090,8 @@ Index *sqlite3CreateIndex(
   */
   for(i=0; i<pList->nExpr; i++){
     Expr *pExpr = pList->a[i].pExpr;
-    if( pExpr && pExpr->op==TK_COLLATE ){
+    assert( pExpr!=0 );
+    if( pExpr->op==TK_COLLATE ){
       nExtra += (1 + sqlite3Strlen30(pExpr->u.zToken));
     }
   }
@@ -3102,39 +3132,52 @@ Index *sqlite3CreateIndex(
     sortOrderMask = 0;    /* Ignore DESC */
   }
 
-  /* Scan the names of the columns of the table to be indexed and
-  ** load the column indices into the Index structure.  Report an error
-  ** if any column is not found.
+  /* Analyze the list of expressions that form the terms of the index and
+  ** report any errors.  In the common case where the expression is exactly
+  ** a table column, store that column in aiColumn[].  For general expressions,
+  ** populate pIndex->aColExpr and store -2 in aiColumn[].
   **
-  ** TODO:  Add a test to make sure that the same column is not named
-  ** more than once within the same index.  Only the first instance of
-  ** the column will ever be used by the optimizer.  Note that using the
-  ** same column more than once cannot be an error because that would 
-  ** break backwards compatibility - it needs to be a warning.
+  ** TODO: Issue a warning if two or more columns of the index are identical.
+  ** TODO: Issue a warning if the table primary key is used as part of the
+  ** index key.
   */
   for(i=0, pListItem=pList->a; i<pList->nExpr; i++, pListItem++){
-    const char *zColName;
-    Expr *pCExpr;
-    int requestedSortOrder;
+    Expr *pCExpr;                  /* The i-th index expression */
+    int requestedSortOrder;        /* ASC or DESC on the i-th expression */
     char *zColl;                   /* Collation sequence name */
 
+    sqlite3StringToId(pListItem->pExpr);
+    sqlite3ResolveSelfReference(pParse, pTab, NC_IdxExpr, pListItem->pExpr, 0);
+    if( pParse->nErr ) goto exit_create_index;
     pCExpr = sqlite3ExprSkipCollate(pListItem->pExpr);
-    if( pCExpr->op!=TK_ID ){
-      sqlite3ErrorMsg(pParse, "indexes on expressions not yet supported");
-      continue;
-    }
-    zColName = pCExpr->u.zToken;
-    for(j=0, pTabCol=pTab->aCol; j<pTab->nCol; j++, pTabCol++){
-      if( sqlite3StrICmp(zColName, pTabCol->zName)==0 ) break;
-    }
-    if( j>=pTab->nCol ){
-      sqlite3ErrorMsg(pParse, "table %s has no column named %s",
-        pTab->zName, zColName);
-      pParse->checkSchema = 1;
-      goto exit_create_index;
+    if( pCExpr->op!=TK_COLUMN ){
+      if( pTab==pParse->pNewTable ){
+        sqlite3ErrorMsg(pParse, "expressions prohibited in PRIMARY KEY and "
+                                "UNIQUE constraints");
+        goto exit_create_index;
+      }
+      if( pIndex->aColExpr==0 ){
+        ExprList *pCopy = sqlite3ExprListDup(db, pList, 0);
+        pIndex->aColExpr = pCopy;
+        if( !db->mallocFailed ){
+          assert( pCopy!=0 );
+          pListItem = &pCopy->a[i];
+        }
+      }
+      j = -2;
+      pIndex->aiColumn[i] = -2;
+      pIndex->uniqNotNull = 0;
+    }else{
+      j = pCExpr->iColumn;
+      assert( j<=0x7fff );
+      if( j<0 ){
+        j = pTab->iPKey;
+      }else if( pTab->aCol[j].notNull==0 ){
+        pIndex->uniqNotNull = 0;
+      }
+      pIndex->aiColumn[i] = (i16)j;
     }
-    assert( j<=0x7fff );
-    pIndex->aiColumn[i] = (i16)j;
+    zColl = 0;
     if( pListItem->pExpr->op==TK_COLLATE ){
       int nColl;
       zColl = pListItem->pExpr->u.zToken;
@@ -3144,21 +3187,26 @@ Index *sqlite3CreateIndex(
       zColl = zExtra;
       zExtra += nColl;
       nExtra -= nColl;
-    }else{
+    }else if( j>=0 ){
       zColl = pTab->aCol[j].zColl;
-      if( !zColl ) zColl = "BINARY";
     }
+    if( !zColl ) zColl = "BINARY";
     if( !db->init.busy && !sqlite3LocateCollSeq(pParse, zColl) ){
       goto exit_create_index;
     }
     pIndex->azColl[i] = zColl;
     requestedSortOrder = pListItem->sortOrder & sortOrderMask;
     pIndex->aSortOrder[i] = (u8)requestedSortOrder;
-    if( pTab->aCol[j].notNull==0 ) pIndex->uniqNotNull = 0;
   }
+
+  /* Append the table key to the end of the index.  For WITHOUT ROWID
+  ** tables (when pPk!=0) this will be the declared PRIMARY KEY.  For
+  ** normal tables (when pPk==0) this will be the rowid.
+  */
   if( pPk ){
     for(j=0; j<pPk->nKeyCol; j++){
       int x = pPk->aiColumn[j];
+      assert( x>=0 );
       if( hasColumn(pIndex->aiColumn, pIndex->nKeyCol, x) ){
         pIndex->nColumn--; 
       }else{
@@ -3209,6 +3257,7 @@ Index *sqlite3CreateIndex(
       for(k=0; k<pIdx->nKeyCol; k++){
         const char *z1;
         const char *z2;
+        assert( pIdx->aiColumn[k]>=0 );
         if( pIdx->aiColumn[k]!=pIndex->aiColumn[k] ) break;
         z1 = pIdx->azColl[k];
         z2 = pIndex->azColl[k];
@@ -3240,6 +3289,7 @@ Index *sqlite3CreateIndex(
   /* Link the new Index structure to its table and to the other
   ** in-memory database structures. 
   */
+  assert( pParse->nErr==0 );
   if( db->init.busy ){
     Index *p;
     assert( sqlite3SchemaMutexHeld(db, 0, pIndex->pSchema) );
@@ -3269,7 +3319,7 @@ Index *sqlite3CreateIndex(
   ** has just been created, it contains no data and the index initialization
   ** step can be skipped.
   */
-  else if( pParse->nErr==0 && (HasRowid(pTab) || pTblName!=0) ){
+  else if( HasRowid(pTab) || pTblName!=0 ){
     Vdbe *v;
     char *zStmt;
     int iMem = ++pParse->nMem;
@@ -4099,12 +4149,16 @@ void sqlite3UniqueConstraint(
   Table *pTab = pIdx->pTable;
 
   sqlite3StrAccumInit(&errMsg, pParse->db, 0, 0, 200);
-  for(j=0; j<pIdx->nKeyCol; j++){
-    char *zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
-    if( j ) sqlite3StrAccumAppend(&errMsg, ", ", 2);
-    sqlite3StrAccumAppendAll(&errMsg, pTab->zName);
-    sqlite3StrAccumAppend(&errMsg, ".", 1);
-    sqlite3StrAccumAppendAll(&errMsg, zCol);
+  if( pIdx->aColExpr ){
+    sqlite3XPrintf(&errMsg, 0, "index '%q'", pIdx->zName);
+  }else{
+    for(j=0; j<pIdx->nKeyCol; j++){
+      char *zCol;
+      assert( pIdx->aiColumn[j]>=0 );
+      zCol = pTab->aCol[pIdx->aiColumn[j]].zName;
+      if( j ) sqlite3StrAccumAppend(&errMsg, ", ", 2);
+      sqlite3XPrintf(&errMsg, 0, "%s.%s", pTab->zName, zCol);
+    }
   }
   zErr = sqlite3StrAccumFinish(&errMsg);
   sqlite3HaltConstraint(pParse, 
diff --git a/src/date.c b/src/date.c
index 6b11d9904..8a66eae90 100644
--- a/src/date.c
+++ b/src/date.c
@@ -1115,14 +1115,14 @@ static void currentTimeFunc(
 void sqlite3RegisterDateTimeFunctions(void){
   static SQLITE_WSD FuncDef aDateTimeFuncs[] = {
 #ifndef SQLITE_OMIT_DATETIME_FUNCS
-    FUNCTION(julianday,        -1, 0, 0, juliandayFunc ),
-    FUNCTION(date,             -1, 0, 0, dateFunc      ),
-    FUNCTION(time,             -1, 0, 0, timeFunc      ),
-    FUNCTION(datetime,         -1, 0, 0, datetimeFunc  ),
-    FUNCTION(strftime,         -1, 0, 0, strftimeFunc  ),
-    FUNCTION(current_time,      0, 0, 0, ctimeFunc     ),
-    FUNCTION(current_timestamp, 0, 0, 0, ctimestampFunc),
-    FUNCTION(current_date,      0, 0, 0, cdateFunc     ),
+    DFUNCTION(julianday,        -1, 0, 0, juliandayFunc ),
+    DFUNCTION(date,             -1, 0, 0, dateFunc      ),
+    DFUNCTION(time,             -1, 0, 0, timeFunc      ),
+    DFUNCTION(datetime,         -1, 0, 0, datetimeFunc  ),
+    DFUNCTION(strftime,         -1, 0, 0, strftimeFunc  ),
+    DFUNCTION(current_time,      0, 0, 0, ctimeFunc     ),
+    DFUNCTION(current_timestamp, 0, 0, 0, ctimestampFunc),
+    DFUNCTION(current_date,      0, 0, 0, cdateFunc     ),
 #else
     STR_FUNCTION(current_time,      0, "%H:%M:%S",          0, currentTimeFunc),
     STR_FUNCTION(current_date,      0, "%Y-%m-%d",          0, currentTimeFunc),
diff --git a/src/dbstat.c b/src/dbstat.c
index c36be020a..f43b14881 100644
--- a/src/dbstat.c
+++ b/src/dbstat.c
@@ -16,6 +16,9 @@
 ** information from an SQLite database in order to implement the
 ** "sqlite3_analyzer" utility.  See the ../tool/spaceanal.tcl script
 ** for an example implementation.
+**
+** Additional information is available on the "dbstat.html" page of the
+** official SQLite documentation.
 */
 
 #include "sqliteInt.h"   /* Requires access to internal data structures */
@@ -64,7 +67,8 @@
   "  unused     INTEGER,          /* Bytes of unused space on this page */" \
   "  mx_payload INTEGER,          /* Largest payload size of all cells */"  \
   "  pgoffset   INTEGER,          /* Offset of page in file */"             \
-  "  pgsize     INTEGER           /* Size of the page */"                   \
+  "  pgsize     INTEGER,          /* Size of the page */"                   \
+  "  schema     TEXT HIDDEN       /* Database schema being analyzed */"     \
   ");"
 
 
@@ -102,6 +106,7 @@ struct StatCursor {
   sqlite3_vtab_cursor base;
   sqlite3_stmt *pStmt;            /* Iterates through set of root pages */
   int isEof;                      /* After pStmt has returned SQLITE_DONE */
+  int iDb;                        /* Schema used for this query */
 
   StatPage aPage[32];
   int iPage;                      /* Current entry in aPage[] */
@@ -179,9 +184,32 @@ static int statDisconnect(sqlite3_vtab *pVtab){
 
 /*
 ** There is no "best-index". This virtual table always does a linear
-** scan of the binary VFS log file.
+** scan.  However, a schema=? constraint should cause this table to
+** operate on a different database schema, so check for it.
+**
+** idxNum is normally 0, but will be 1 if a schema=? constraint exists.
 */
 static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
+  int i;
+
+  pIdxInfo->estimatedCost = 1.0e6;  /* Initial cost estimate */
+
+  /* Look for a valid schema=? constraint.  If found, change the idxNum to
+  ** 1 and request the value of that constraint be sent to xFilter.  And
+  ** lower the cost estimate to encourage the constrained version to be
+  ** used.
+  */
+  for(i=0; i<pIdxInfo->nConstraint; i++){
+    if( pIdxInfo->aConstraint[i].usable==0 ) continue;
+    if( pIdxInfo->aConstraint[i].op!=SQLITE_INDEX_CONSTRAINT_EQ ) continue;
+    if( pIdxInfo->aConstraint[i].iColumn!=10 ) continue;
+    pIdxInfo->idxNum = 1;
+    pIdxInfo->estimatedCost = 1.0;
+    pIdxInfo->aConstraintUsage[i].argvIndex = 1;
+    pIdxInfo->aConstraintUsage[i].omit = 1;
+    break;
+  }
+
 
   /* Records are always returned in ascending order of (name, path). 
   ** If this will satisfy the client, set the orderByConsumed flag so that 
@@ -201,7 +229,6 @@ static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
     pIdxInfo->orderByConsumed = 1;
   }
 
-  pIdxInfo->estimatedCost = 10.0;
   return SQLITE_OK;
 }
 
@@ -211,36 +238,18 @@ static int statBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
 static int statOpen(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCursor){
   StatTable *pTab = (StatTable *)pVTab;
   StatCursor *pCsr;
-  int rc;
 
   pCsr = (StatCursor *)sqlite3_malloc64(sizeof(StatCursor));
   if( pCsr==0 ){
-    rc = SQLITE_NOMEM;
+    return SQLITE_NOMEM;
   }else{
-    char *zSql;
     memset(pCsr, 0, sizeof(StatCursor));
     pCsr->base.pVtab = pVTab;
-
-    zSql = sqlite3_mprintf(
-        "SELECT 'sqlite_master' AS name, 1 AS rootpage, 'table' AS type"
-        "  UNION ALL  "
-        "SELECT name, rootpage, type"
-        "  FROM \"%w\".sqlite_master WHERE rootpage!=0"
-        "  ORDER BY name", pTab->db->aDb[pTab->iDb].zName);
-    if( zSql==0 ){
-      rc = SQLITE_NOMEM;
-    }else{
-      rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pCsr->pStmt, 0);
-      sqlite3_free(zSql);
-    }
-    if( rc!=SQLITE_OK ){
-      sqlite3_free(pCsr);
-      pCsr = 0;
-    }
+    pCsr->iDb = pTab->iDb;
   }
 
   *ppCursor = (sqlite3_vtab_cursor *)pCsr;
-  return rc;
+  return SQLITE_OK;
 }
 
 static void statClearPage(StatPage *p){
@@ -265,6 +274,7 @@ static void statResetCsr(StatCursor *pCsr){
   pCsr->iPage = 0;
   sqlite3_free(pCsr->zPath);
   pCsr->zPath = 0;
+  pCsr->isEof = 0;
 }
 
 /*
@@ -427,7 +437,7 @@ static int statNext(sqlite3_vtab_cursor *pCursor){
   char *z;
   StatCursor *pCsr = (StatCursor *)pCursor;
   StatTable *pTab = (StatTable *)pCursor->pVtab;
-  Btree *pBt = pTab->db->aDb[pTab->iDb].pBt;
+  Btree *pBt = pTab->db->aDb[pCsr->iDb].pBt;
   Pager *pPager = sqlite3BtreePager(pBt);
 
   sqlite3_free(pCsr->zPath);
@@ -565,9 +575,43 @@ static int statFilter(
   int argc, sqlite3_value **argv
 ){
   StatCursor *pCsr = (StatCursor *)pCursor;
-
+  StatTable *pTab = (StatTable*)(pCursor->pVtab);
+  char *zSql;
+  int rc = SQLITE_OK;
+  char *zMaster;
+
+  if( idxNum==1 ){
+    const char *zDbase = (const char*)sqlite3_value_text(argv[0]);
+    pCsr->iDb = sqlite3FindDbName(pTab->db, zDbase);
+    if( pCsr->iDb<0 ){
+      sqlite3_free(pCursor->pVtab->zErrMsg);
+      pCursor->pVtab->zErrMsg = sqlite3_mprintf("no such schema: %s", zDbase);
+      return pCursor->pVtab->zErrMsg ? SQLITE_ERROR : SQLITE_NOMEM;
+    }
+  }else{
+    pCsr->iDb = pTab->iDb;
+  }
   statResetCsr(pCsr);
-  return statNext(pCursor);
+  sqlite3_finalize(pCsr->pStmt);
+  pCsr->pStmt = 0;
+  zMaster = pCsr->iDb==1 ? "sqlite_temp_master" : "sqlite_master";
+  zSql = sqlite3_mprintf(
+      "SELECT 'sqlite_master' AS name, 1 AS rootpage, 'table' AS type"
+      "  UNION ALL  "
+      "SELECT name, rootpage, type"
+      "  FROM \"%w\".%s WHERE rootpage!=0"
+      "  ORDER BY name", pTab->db->aDb[pCsr->iDb].zName, zMaster);
+  if( zSql==0 ){
+    return SQLITE_NOMEM;
+  }else{
+    rc = sqlite3_prepare_v2(pTab->db, zSql, -1, &pCsr->pStmt, 0);
+    sqlite3_free(zSql);
+  }
+
+  if( rc==SQLITE_OK ){
+    rc = statNext(pCursor);
+  }
+  return rc;
 }
 
 static int statColumn(
@@ -604,10 +648,15 @@ static int statColumn(
     case 8:            /* pgoffset */
       sqlite3_result_int64(ctx, pCsr->iOffset);
       break;
-    default:           /* pgsize */
-      assert( i==9 );
+    case 9:            /* pgsize */
       sqlite3_result_int(ctx, pCsr->szPage);
       break;
+    default: {          /* schema */
+      sqlite3 *db = sqlite3_context_db_handle(ctx);
+      int iDb = pCsr->iDb;
+      sqlite3_result_text(ctx, db->aDb[iDb].zName, -1, SQLITE_STATIC);
+      break;
+    }
   }
   return SQLITE_OK;
 }
diff --git a/src/delete.c b/src/delete.c
index 539abb162..860b2cf11 100644
--- a/src/delete.c
+++ b/src/delete.c
@@ -235,7 +235,7 @@ void sqlite3DeleteFrom(
   int iDb;               /* Database number */
   int memCnt = -1;       /* Memory cell used for change counting */
   int rcauth;            /* Value returned by authorization callback */
-  int okOnePass;         /* True for one-pass algorithm without the FIFO */
+  int eOnePass;          /* ONEPASS_OFF or _SINGLE or _MULTI */
   int aiCurOnePass[2];   /* The write cursors opened by WHERE_ONEPASS */
   u8 *aToOpen = 0;       /* Open cursor iTabCur+j if aToOpen[j] is true */
   Index *pPk;            /* The PRIMARY KEY index on the table */
@@ -247,12 +247,12 @@ void sqlite3DeleteFrom(
   int iRowSet = 0;       /* Register for rowset of rows to delete */
   int addrBypass = 0;    /* Address of jump over the delete logic */
   int addrLoop = 0;      /* Top of the delete loop */
-  int addrDelete = 0;    /* Jump directly to the delete logic */
   int addrEphOpen = 0;   /* Instruction to open the Ephemeral table */
  
 #ifndef SQLITE_OMIT_TRIGGER
   int isView;                  /* True if attempting to delete from a view */
   Trigger *pTrigger;           /* List of table triggers, if required */
+  int bComplex;                /* True if there are either triggers or FKs */
 #endif
 
   memset(&sContext, 0, sizeof(sContext));
@@ -276,9 +276,11 @@ void sqlite3DeleteFrom(
 #ifndef SQLITE_OMIT_TRIGGER
   pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
   isView = pTab->pSelect!=0;
+  bComplex = pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0);
 #else
 # define pTrigger 0
 # define isView 0
+# define bComplex 0
 #endif
 #ifdef SQLITE_OMIT_VIEW
 # undef isView
@@ -359,8 +361,10 @@ void sqlite3DeleteFrom(
   ** It is easier just to erase the whole table. Prior to version 3.6.5,
   ** this optimization caused the row change count (the value returned by 
   ** API function sqlite3_count_changes) to be set incorrectly.  */
-  if( rcauth==SQLITE_OK && pWhere==0 && !pTrigger && !IsVirtual(pTab) 
-   && 0==sqlite3FkRequired(pParse, pTab, 0, 0)
+  if( rcauth==SQLITE_OK
+   && pWhere==0
+   && !bComplex
+   && !IsVirtual(pTab)
   ){
     assert( !isView );
     sqlite3TableLock(pParse, iDb, pTab->tnum, 1, pTab->zName);
@@ -375,6 +379,8 @@ void sqlite3DeleteFrom(
   }else
 #endif /* SQLITE_OMIT_TRUNCATE_OPTIMIZATION */
   {
+    u16 wcf = WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK;
+    wcf |= (bComplex ? 0 : WHERE_ONEPASS_MULTIROW);
     if( HasRowid(pTab) ){
       /* For a rowid table, initialize the RowSet to an empty set */
       pPk = 0;
@@ -395,13 +401,17 @@ void sqlite3DeleteFrom(
     }
   
     /* Construct a query to find the rowid or primary key for every row
-    ** to be deleted, based on the WHERE clause.
+    ** to be deleted, based on the WHERE clause. Set variable eOnePass
+    ** to indicate the strategy used to implement this delete:
+    **
+    **  ONEPASS_OFF:    Two-pass approach - use a FIFO for rowids/PK values.
+    **  ONEPASS_SINGLE: One-pass approach - at most one row deleted.
+    **  ONEPASS_MULTI:  One-pass approach - any number of rows may be deleted.
     */
-    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, 
-                               WHERE_ONEPASS_DESIRED|WHERE_DUPLICATES_OK,
-                               iTabCur+1);
+    pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, 0, 0, wcf, iTabCur+1);
     if( pWInfo==0 ) goto delete_from_cleanup;
-    okOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+    eOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
+    assert( IsVirtual(pTab)==0 || eOnePass==ONEPASS_OFF );
   
     /* Keep track of the number of rows to be deleted */
     if( db->flags & SQLITE_CountRows ){
@@ -411,6 +421,7 @@ void sqlite3DeleteFrom(
     /* Extract the rowid or primary key for the current row */
     if( pPk ){
       for(i=0; i<nPk; i++){
+        assert( pPk->aiColumn[i]>=(-1) );
         sqlite3ExprCodeGetColumnOfTable(v, pTab, iTabCur,
                                         pPk->aiColumn[i], iPk+i);
       }
@@ -421,11 +432,10 @@ void sqlite3DeleteFrom(
       if( iKey>pParse->nMem ) pParse->nMem = iKey;
     }
   
-    if( okOnePass ){
-      /* For ONEPASS, no need to store the rowid/primary-key.  There is only
+    if( eOnePass!=ONEPASS_OFF ){
+      /* For ONEPASS, no need to store the rowid/primary-key. There is only
       ** one, so just keep it in its register(s) and fall through to the
-      ** delete code.
-      */
+      ** delete code.  */
       nKey = nPk; /* OP_Found will use an unpacked key */
       aToOpen = sqlite3DbMallocRaw(db, nIdx+2);
       if( aToOpen==0 ){
@@ -437,27 +447,27 @@ void sqlite3DeleteFrom(
       if( aiCurOnePass[0]>=0 ) aToOpen[aiCurOnePass[0]-iTabCur] = 0;
       if( aiCurOnePass[1]>=0 ) aToOpen[aiCurOnePass[1]-iTabCur] = 0;
       if( addrEphOpen ) sqlite3VdbeChangeToNoop(v, addrEphOpen);
-      addrDelete = sqlite3VdbeAddOp0(v, OP_Goto); /* Jump to DELETE logic */
-    }else if( pPk ){
-      /* Construct a composite key for the row to be deleted and remember it */
-      iKey = ++pParse->nMem;
-      nKey = 0;   /* Zero tells OP_Found to use a composite key */
-      sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
-                        sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
-      sqlite3VdbeAddOp2(v, OP_IdxInsert, iEphCur, iKey);
     }else{
-      /* Get the rowid of the row to be deleted and remember it in the RowSet */
-      nKey = 1;  /* OP_Seek always uses a single rowid */
-      sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
+      if( pPk ){
+        /* Add the PK key for this row to the temporary table */
+        iKey = ++pParse->nMem;
+        nKey = 0;   /* Zero tells OP_Found to use a composite key */
+        sqlite3VdbeAddOp4(v, OP_MakeRecord, iPk, nPk, iKey,
+            sqlite3IndexAffinityStr(pParse->db, pPk), nPk);
+        sqlite3VdbeAddOp2(v, OP_IdxInsert, iEphCur, iKey);
+      }else{
+        /* Add the rowid of the row to be deleted to the RowSet */
+        nKey = 1;  /* OP_Seek always uses a single rowid */
+        sqlite3VdbeAddOp2(v, OP_RowSetAdd, iRowSet, iKey);
+      }
     }
   
-    /* End of the WHERE loop */
-    sqlite3WhereEnd(pWInfo);
-    if( okOnePass ){
-      /* Bypass the delete logic below if the WHERE loop found zero rows */
+    /* If this DELETE cannot use the ONEPASS strategy, this is the 
+    ** end of the WHERE loop */
+    if( eOnePass!=ONEPASS_OFF ){
       addrBypass = sqlite3VdbeMakeLabel(v);
-      sqlite3VdbeGoto(v, addrBypass);
-      sqlite3VdbeJumpHere(v, addrDelete);
+    }else{
+      sqlite3WhereEnd(pWInfo);
     }
   
     /* Unless this is a view, open cursors for the table we are 
@@ -466,20 +476,23 @@ void sqlite3DeleteFrom(
     ** triggers.
     */
     if( !isView ){
+      int iAddrOnce = 0;
+      if( eOnePass==ONEPASS_MULTI ){
+        iAddrOnce = sqlite3CodeOnce(pParse); VdbeCoverage(v);
+      }
       testcase( IsVirtual(pTab) );
       sqlite3OpenTableAndIndices(pParse, pTab, OP_OpenWrite, iTabCur, aToOpen,
                                  &iDataCur, &iIdxCur);
       assert( pPk || IsVirtual(pTab) || iDataCur==iTabCur );
       assert( pPk || IsVirtual(pTab) || iIdxCur==iDataCur+1 );
+      if( eOnePass==ONEPASS_MULTI ) sqlite3VdbeJumpHere(v, iAddrOnce);
     }
   
     /* Set up a loop over the rowids/primary-keys that were found in the
     ** where-clause loop above.
     */
-    if( okOnePass ){
-      /* Just one row.  Hence the top-of-loop is a no-op */
+    if( eOnePass!=ONEPASS_OFF ){
       assert( nKey==nPk );  /* OP_Found will use an unpacked key */
-      assert( !IsVirtual(pTab) );
       if( aToOpen[iDataCur-iTabCur] ){
         assert( pPk!=0 || pTab->pSelect!=0 );
         sqlite3VdbeAddOp4Int(v, OP_NotFound, iDataCur, addrBypass, iKey, nKey);
@@ -507,13 +520,18 @@ void sqlite3DeleteFrom(
 #endif
     {
       int count = (pParse->nested==0);    /* True to count changes */
+      int iIdxNoSeek = -1;
+      if( bComplex==0 && aiCurOnePass[1]!=iDataCur ){
+        iIdxNoSeek = aiCurOnePass[1];
+      }
       sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                               iKey, nKey, count, OE_Default, okOnePass);
+          iKey, nKey, count, OE_Default, eOnePass, iIdxNoSeek);
     }
   
     /* End of the loop over all rowids/primary-keys. */
-    if( okOnePass ){
+    if( eOnePass!=ONEPASS_OFF ){
       sqlite3VdbeResolveLabel(v, addrBypass);
+      sqlite3WhereEnd(pWInfo);
     }else if( pPk ){
       sqlite3VdbeAddOp2(v, OP_Next, iEphCur, addrLoop+1); VdbeCoverage(v);
       sqlite3VdbeJumpHere(v, addrLoop);
@@ -585,6 +603,25 @@ delete_from_cleanup:
 **       sequence of nPk memory cells starting at iPk.  If nPk==0 that means
 **       that a search record formed from OP_MakeRecord is contained in the
 **       single memory location iPk.
+**
+** eMode:
+**   Parameter eMode may be passed either ONEPASS_OFF (0), ONEPASS_SINGLE, or
+**   ONEPASS_MULTI.  If eMode is not ONEPASS_OFF, then the cursor
+**   iDataCur already points to the row to delete. If eMode is ONEPASS_OFF
+**   then this function must seek iDataCur to the entry identified by iPk
+**   and nPk before reading from it.
+**
+**   If eMode is ONEPASS_MULTI, then this call is being made as part
+**   of a ONEPASS delete that affects multiple rows. In this case, if 
+**   iIdxNoSeek is a valid cursor number (>=0), then its position should
+**   be preserved following the delete operation. Or, if iIdxNoSeek is not
+**   a valid cursor number, the position of iDataCur should be preserved
+**   instead.
+**
+** iIdxNoSeek:
+**   If iIdxNoSeek is a valid cursor number (>=0), then it identifies an
+**   index cursor (from within array of cursors starting at iIdxCur) that
+**   already points to the index entry to be deleted.
 */
 void sqlite3GenerateRowDelete(
   Parse *pParse,     /* Parsing context */
@@ -596,7 +633,8 @@ void sqlite3GenerateRowDelete(
   i16 nPk,           /* Number of PRIMARY KEY memory cells */
   u8 count,          /* If non-zero, increment the row change counter */
   u8 onconf,         /* Default ON CONFLICT policy for triggers */
-  u8 bNoSeek         /* iDataCur is already pointing to the row to delete */
+  u8 eMode,          /* ONEPASS_OFF, _SINGLE, or _MULTI.  See above */
+  int iIdxNoSeek     /* Cursor number of cursor that does not need seeking */
 ){
   Vdbe *v = pParse->pVdbe;        /* Vdbe */
   int iOld = 0;                   /* First register in OLD.* array */
@@ -613,7 +651,7 @@ void sqlite3GenerateRowDelete(
   ** not attempt to delete it or fire any DELETE triggers.  */
   iLabel = sqlite3VdbeMakeLabel(v);
   opSeek = HasRowid(pTab) ? OP_NotExists : OP_NotFound;
-  if( !bNoSeek ){
+  if( eMode==ONEPASS_OFF ){
     sqlite3VdbeAddOp4Int(v, opSeek, iDataCur, iLabel, iPk, nPk);
     VdbeCoverageIf(v, opSeek==OP_NotExists);
     VdbeCoverageIf(v, opSeek==OP_NotFound);
@@ -673,11 +711,15 @@ void sqlite3GenerateRowDelete(
   ** a view (in which case the only effect of the DELETE statement is to
   ** fire the INSTEAD OF triggers).  */ 
   if( pTab->pSelect==0 ){
-    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, 0);
+    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,iIdxNoSeek);
     sqlite3VdbeAddOp2(v, OP_Delete, iDataCur, (count?OPFLAG_NCHANGE:0));
     if( count ){
       sqlite3VdbeChangeP4(v, -1, pTab->zName, P4_TRANSIENT);
     }
+    if( iIdxNoSeek>=0 ){
+      sqlite3VdbeAddOp1(v, OP_Delete, iIdxNoSeek);
+    }
+    sqlite3VdbeChangeP5(v, eMode==ONEPASS_MULTI);
   }
 
   /* Do any ON CASCADE, SET NULL or SET DEFAULT operations required to
@@ -720,7 +762,8 @@ void sqlite3GenerateRowIndexDelete(
   Table *pTab,       /* Table containing the row to be deleted */
   int iDataCur,      /* Cursor of table holding data. */
   int iIdxCur,       /* First index cursor */
-  int *aRegIdx       /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
+  int *aRegIdx,      /* Only delete if aRegIdx!=0 && aRegIdx[i]>0 */
+  int iIdxNoSeek     /* Do not delete from this cursor */
 ){
   int i;             /* Index loop counter */
   int r1 = -1;       /* Register holding an index key */
@@ -736,11 +779,12 @@ void sqlite3GenerateRowIndexDelete(
     assert( iIdxCur+i!=iDataCur || pPk==pIdx );
     if( aRegIdx!=0 && aRegIdx[i]==0 ) continue;
     if( pIdx==pPk ) continue;
+    if( iIdxCur+i==iIdxNoSeek ) continue;
     VdbeModuleComment((v, "GenRowIdxDel for %s", pIdx->zName));
     r1 = sqlite3GenerateIndexKey(pParse, pIdx, iDataCur, 0, 1,
-                                 &iPartIdxLabel, pPrior, r1);
+        &iPartIdxLabel, pPrior, r1);
     sqlite3VdbeAddOp3(v, OP_IdxDelete, iIdxCur+i, r1,
-                      pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
+        pIdx->uniqNotNull ? pIdx->nKeyCol : pIdx->nColumn);
     sqlite3ResolvePartIdxLabel(pParse, iPartIdxLabel);
     pPrior = pIdx;
   }
@@ -789,14 +833,13 @@ int sqlite3GenerateIndexKey(
 ){
   Vdbe *v = pParse->pVdbe;
   int j;
-  Table *pTab = pIdx->pTable;
   int regBase;
   int nCol;
 
   if( piPartIdxLabel ){
     if( pIdx->pPartIdxWhere ){
       *piPartIdxLabel = sqlite3VdbeMakeLabel(v);
-      pParse->iPartIdxTab = iDataCur;
+      pParse->iSelfTab = iDataCur;
       sqlite3ExprCachePush(pParse);
       sqlite3ExprIfFalseDup(pParse, pIdx->pPartIdxWhere, *piPartIdxLabel, 
                             SQLITE_JUMPIFNULL);
@@ -808,9 +851,14 @@ int sqlite3GenerateIndexKey(
   regBase = sqlite3GetTempRange(pParse, nCol);
   if( pPrior && (regBase!=regPrior || pPrior->pPartIdxWhere) ) pPrior = 0;
   for(j=0; j<nCol; j++){
-    if( pPrior && pPrior->aiColumn[j]==pIdx->aiColumn[j] ) continue;
-    sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, pIdx->aiColumn[j],
-                                    regBase+j);
+    if( pPrior
+     && pPrior->aiColumn[j]==pIdx->aiColumn[j]
+     && pPrior->aiColumn[j]>=(-1)
+    ){
+      /* This column was already computed by the previous index */
+      continue;
+    }
+    sqlite3ExprCodeLoadIndexColumn(pParse, pIdx, iDataCur, j, regBase+j);
     /* If the column affinity is REAL but the number is an integer, then it
     ** might be stored in the table as an integer (using a compact
     ** representation) then converted to REAL by an OP_RealAffinity opcode.
diff --git a/src/expr.c b/src/expr.c
index c7ebf9364..aa9cc7b52 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -91,7 +91,7 @@ Expr *sqlite3ExprAddCollateString(Parse *pParse, Expr *pExpr, const char *zC){
 }
 
 /*
-** Skip over any TK_COLLATE or TK_AS operators and any unlikely()
+** Skip over any TK_COLLATE operators and any unlikely()
 ** or likelihood() function at the root of an expression.
 */
 Expr *sqlite3ExprSkipCollate(Expr *pExpr){
@@ -102,7 +102,7 @@ Expr *sqlite3ExprSkipCollate(Expr *pExpr){
       assert( pExpr->op==TK_FUNCTION );
       pExpr = pExpr->x.pList->a[0].pExpr;
     }else{
-      assert( pExpr->op==TK_COLLATE || pExpr->op==TK_AS );
+      assert( pExpr->op==TK_COLLATE );
       pExpr = pExpr->pLeft;
     }
   }   
@@ -2448,6 +2448,28 @@ static void sqlite3ExprCachePinRegister(Parse *pParse, int iReg){
   }
 }
 
+/* Generate code that will load into register regOut a value that is
+** appropriate for the iIdxCol-th column of index pIdx.
+*/
+void sqlite3ExprCodeLoadIndexColumn(
+  Parse *pParse,  /* The parsing context */
+  Index *pIdx,    /* The index whose column is to be loaded */
+  int iTabCur,    /* Cursor pointing to a table row */
+  int iIdxCol,    /* The column of the index to be loaded */
+  int regOut      /* Store the index column value in this register */
+){
+  i16 iTabCol = pIdx->aiColumn[iIdxCol];
+  if( iTabCol>=(-1) ){
+    sqlite3ExprCodeGetColumnOfTable(pParse->pVdbe, pIdx->pTable, iTabCur,
+                                    iTabCol, regOut);
+    return;
+  }
+  assert( pIdx->aColExpr );
+  assert( pIdx->aColExpr->nExpr>iIdxCol );
+  pParse->iSelfTab = iTabCur;
+  sqlite3ExprCode(pParse, pIdx->aColExpr->a[iIdxCol].pExpr, regOut);
+}
+
 /*
 ** Generate code to extract the value of the iCol-th column of a table.
 */
@@ -2633,8 +2655,9 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
           inReg = pExpr->iColumn + pParse->ckBase;
           break;
         }else{
-          /* Deleting from a partial index */
-          iTab = pParse->iPartIdxTab;
+          /* Coding an expression that is part of an index where column names
+          ** in the index refer to the table to which the index belongs */
+          iTab = pParse->iSelfTab;
         }
       }
       inReg = sqlite3ExprCodeGetColumn(pParse, pExpr->pTab,
@@ -2694,10 +2717,6 @@ int sqlite3ExprCodeTarget(Parse *pParse, Expr *pExpr, int target){
       inReg = pExpr->iTable;
       break;
     }
-    case TK_AS: {
-      inReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft, target);
-      break;
-    }
 #ifndef SQLITE_OMIT_CAST
     case TK_CAST: {
       /* Expressions of the form:   CAST(pLeft AS token) */
@@ -3781,7 +3800,9 @@ int sqlite3ExprCompare(Expr *pA, Expr *pB, int iTab){
     return 2;
   }
   if( pA->op!=TK_COLUMN && ALWAYS(pA->op!=TK_AGG_COLUMN) && pA->u.zToken ){
-    if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
+    if( pA->op==TK_FUNCTION ){
+      if( sqlite3StrICmp(pA->u.zToken,pB->u.zToken)!=0 ) return 2;
+    }else if( strcmp(pA->u.zToken,pB->u.zToken)!=0 ){
       return pA->op==TK_COLLATE ? 1 : 2;
     }
   }
diff --git a/src/func.c b/src/func.c
index 6ecd74396..8ea116932 100644
--- a/src/func.c
+++ b/src/func.c
@@ -1737,15 +1737,15 @@ void sqlite3RegisterGlobalFunctions(void){
     VFUNCTION(random,            0, 0, 0, randomFunc       ),
     VFUNCTION(randomblob,        1, 0, 0, randomBlob       ),
     FUNCTION(nullif,             2, 0, 1, nullifFunc       ),
-    FUNCTION(sqlite_version,     0, 0, 0, versionFunc      ),
-    FUNCTION(sqlite_source_id,   0, 0, 0, sourceidFunc     ),
+    DFUNCTION(sqlite_version,    0, 0, 0, versionFunc      ),
+    DFUNCTION(sqlite_source_id,  0, 0, 0, sourceidFunc     ),
     FUNCTION(sqlite_log,         2, 0, 0, errlogFunc       ),
 #if SQLITE_USER_AUTHENTICATION
     FUNCTION(sqlite_crypt,       2, 0, 0, sqlite3CryptFunc ),
 #endif
 #ifndef SQLITE_OMIT_COMPILEOPTION_DIAGS
-    FUNCTION(sqlite_compileoption_used,1, 0, 0, compileoptionusedFunc  ),
-    FUNCTION(sqlite_compileoption_get, 1, 0, 0, compileoptiongetFunc  ),
+    DFUNCTION(sqlite_compileoption_used,1, 0, 0, compileoptionusedFunc  ),
+    DFUNCTION(sqlite_compileoption_get, 1, 0, 0, compileoptiongetFunc  ),
 #endif /* SQLITE_OMIT_COMPILEOPTION_DIAGS */
     FUNCTION(quote,              1, 0, 0, quoteFunc        ),
     VFUNCTION(last_insert_rowid, 0, 0, 0, last_insert_rowid),
@@ -1757,8 +1757,8 @@ void sqlite3RegisterGlobalFunctions(void){
     FUNCTION(soundex,            1, 0, 0, soundexFunc      ),
   #endif
   #ifndef SQLITE_OMIT_LOAD_EXTENSION
-    FUNCTION(load_extension,     1, 0, 0, loadExt          ),
-    FUNCTION(load_extension,     2, 0, 0, loadExt          ),
+    VFUNCTION(load_extension,    1, 0, 0, loadExt          ),
+    VFUNCTION(load_extension,    2, 0, 0, loadExt          ),
   #endif
     AGGREGATE(sum,               1, 0, 0, sumStep,         sumFinalize    ),
     AGGREGATE(total,             1, 0, 0, sumStep,         totalFinalize    ),
diff --git a/src/insert.c b/src/insert.c
index 93d1f785d..53b429c1f 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -88,7 +88,18 @@ const char *sqlite3IndexAffinityStr(sqlite3 *db, Index *pIdx){
     }
     for(n=0; n<pIdx->nColumn; n++){
       i16 x = pIdx->aiColumn[n];
-      pIdx->zColAff[n] = x<0 ? SQLITE_AFF_INTEGER : pTab->aCol[x].affinity;
+      if( x>=0 ){
+        pIdx->zColAff[n] = pTab->aCol[x].affinity;
+      }else if( x==(-1) ){
+        pIdx->zColAff[n] = SQLITE_AFF_INTEGER;
+      }else{
+        char aff;
+        assert( x==(-2) );
+        assert( pIdx->aColExpr!=0 );
+        aff = sqlite3ExprAffinity(pIdx->aColExpr->a[n].pExpr);
+        if( aff==0 ) aff = SQLITE_AFF_BLOB;
+        pIdx->zColAff[n] = aff;
+      }
     }
     pIdx->zColAff[n] = 0;
   }
@@ -1336,10 +1347,13 @@ void sqlite3GenerateConstraintChecks(
         if( pTrigger || sqlite3FkRequired(pParse, pTab, 0, 0) ){
           sqlite3MultiWrite(pParse);
           sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                                   regNewData, 1, 0, OE_Replace, 1);
-        }else if( pTab->pIndex ){
-          sqlite3MultiWrite(pParse);
-          sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, 0);
+                                   regNewData, 1, 0, OE_Replace,
+                                   ONEPASS_SINGLE, -1);
+        }else{
+          if( pTab->pIndex ){
+            sqlite3MultiWrite(pParse);
+            sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur,0,-1);
+          }
         }
         seenReplace = 1;
         break;
@@ -1394,15 +1408,22 @@ void sqlite3GenerateConstraintChecks(
     for(i=0; i<pIdx->nColumn; i++){
       int iField = pIdx->aiColumn[i];
       int x;
-      if( iField<0 || iField==pTab->iPKey ){
-        if( regRowid==regIdx+i ) continue; /* ROWID already in regIdx+i */
-        x = regNewData;
-        regRowid =  pIdx->pPartIdxWhere ? -1 : regIdx+i;
+      if( iField==(-2) ){
+        pParse->ckBase = regNewData+1;
+        sqlite3ExprCode(pParse, pIdx->aColExpr->a[i].pExpr, regIdx+i);
+        pParse->ckBase = 0;
+        VdbeComment((v, "%s column %d", pIdx->zName, i));
       }else{
-        x = iField + regNewData + 1;
+        if( iField==(-1) || iField==pTab->iPKey ){
+          if( regRowid==regIdx+i ) continue; /* ROWID already in regIdx+i */
+          x = regNewData;
+          regRowid =  pIdx->pPartIdxWhere ? -1 : regIdx+i;
+        }else{
+          x = iField + regNewData + 1;
+        }
+        sqlite3VdbeAddOp2(v, OP_SCopy, x, regIdx+i);
+        VdbeComment((v, "%s", iField<0 ? "rowid" : pTab->aCol[iField].zName));
       }
-      sqlite3VdbeAddOp2(v, OP_SCopy, x, regIdx+i);
-      VdbeComment((v, "%s", iField<0 ? "rowid" : pTab->aCol[iField].zName));
     }
     sqlite3VdbeAddOp3(v, OP_MakeRecord, regIdx, pIdx->nColumn, aRegIdx[ix]);
     VdbeComment((v, "for %s", pIdx->zName));
@@ -1510,7 +1531,8 @@ void sqlite3GenerateConstraintChecks(
           pTrigger = sqlite3TriggersExist(pParse, pTab, TK_DELETE, 0, 0);
         }
         sqlite3GenerateRowDelete(pParse, pTab, pTrigger, iDataCur, iIdxCur,
-                                 regR, nPkField, 0, OE_Replace, pIdx==pPk);
+            regR, nPkField, 0, OE_Replace,
+            (pIdx==pPk ? ONEPASS_SINGLE : ONEPASS_OFF), -1);
         seenReplace = 1;
         break;
       }
@@ -1723,6 +1745,13 @@ static int xferCompatibleIndex(Index *pDest, Index *pSrc){
     if( pSrc->aiColumn[i]!=pDest->aiColumn[i] ){
       return 0;   /* Different columns indexed */
     }
+    if( pSrc->aiColumn[i]==(-2) ){
+      assert( pSrc->aColExpr!=0 && pDest->aColExpr!=0 );
+      if( sqlite3ExprCompare(pSrc->aColExpr->a[i].pExpr,
+                             pDest->aColExpr->a[i].pExpr, -1)!=0 ){
+        return 0;   /* Different expressions in the index */
+      }
+    }
     if( pSrc->aSortOrder[i]!=pDest->aSortOrder[i] ){
       return 0;   /* Different sort orders */
     }
diff --git a/src/lempar.c b/src/lempar.c
index b6c60a25b..5e5a11aea 100644
--- a/src/lempar.c
+++ b/src/lempar.c
@@ -56,15 +56,19 @@
 **    ParseARG_PDECL     A parameter declaration for the %extra_argument
 **    ParseARG_STORE     Code to store %extra_argument into yypParser
 **    ParseARG_FETCH     Code to extract %extra_argument from yypParser
-**    YYNSTATE           the combined number of states.
-**    YYNRULE            the number of rules in the grammar
 **    YYERRORSYMBOL      is the code number of the error symbol.  If not
 **                       defined, then do no error processing.
+**    YYNSTATE           the combined number of states.
+**    YYNRULE            the number of rules in the grammar
+**    YY_MAX_SHIFT       Maximum value for shift actions
+**    YY_MIN_SHIFTREDUCE Minimum value for shift-reduce actions
+**    YY_MAX_SHIFTREDUCE Maximum value for shift-reduce actions
+**    YY_MIN_REDUCE      Maximum value for reduce actions
+**    YY_ERROR_ACTION    The yy_action[] code for syntax error
+**    YY_ACCEPT_ACTION   The yy_action[] code for accept
+**    YY_NO_ACTION       The yy_action[] code for no-op
 */
 %%
-#define YY_NO_ACTION      (YYNSTATE+YYNRULE+2)
-#define YY_ACCEPT_ACTION  (YYNSTATE+YYNRULE+1)
-#define YY_ERROR_ACTION   (YYNSTATE+YYNRULE)
 
 /* The yyzerominor constant is used to initialize instances of
 ** YYMINORTYPE objects to zero. */
@@ -91,16 +95,20 @@ static const YYMINORTYPE yyzerominor = { 0 };
 ** Suppose the action integer is N.  Then the action is determined as
 ** follows
 **
-**   0 <= N < YYNSTATE                  Shift N.  That is, push the lookahead
+**   0 <= N <= YY_MAX_SHIFT             Shift N.  That is, push the lookahead
 **                                      token onto the stack and goto state N.
 **
-**   YYNSTATE <= N < YYNSTATE+YYNRULE   Reduce by rule N-YYNSTATE.
+**   N between YY_MIN_SHIFTREDUCE       Shift to an arbitrary state then
+**     and YY_MAX_SHIFTREDUCE           reduce by rule N-YY_MIN_SHIFTREDUCE.
 **
-**   N == YYNSTATE+YYNRULE              A syntax error has occurred.
+**   N between YY_MIN_REDUCE            Reduce by rule N-YY_MIN_REDUCE
+**     and YY_MAX_REDUCE
+
+**   N == YY_ERROR_ACTION               A syntax error has occurred.
 **
-**   N == YYNSTATE+YYNRULE+1            The parser accepts its input.
+**   N == YY_ACCEPT_ACTION              The parser accepts its input.
 **
-**   N == YYNSTATE+YYNRULE+2            No such action.  Denotes unused
+**   N == YY_NO_ACTION                  No such action.  Denotes unused
 **                                      slots in the yy_action[] table.
 **
 ** The action table is constructed as a single large table named yy_action[].
@@ -159,9 +167,13 @@ static const YYCODETYPE yyFallback[] = {
 **   +  The semantic value stored at this level of the stack.  This is
 **      the information used by the action routines in the grammar.
 **      It is sometimes called the "minor" token.
+**
+** After the "shift" half of a SHIFTREDUCE action, the stateno field
+** actually contains the reduce action for the second half of the
+** SHIFTREDUCE.
 */
 struct yyStackEntry {
-  YYACTIONTYPE stateno;  /* The state-number */
+  YYACTIONTYPE stateno;  /* The state-number, or reduce action in SHIFTREDUCE */
   YYCODETYPE major;      /* The major token value.  This is the code
                          ** number for the token at this stack level */
   YYMINORTYPE minor;     /* The user-supplied minor token value.  This
@@ -395,10 +407,10 @@ static int yy_find_shift_action(
   int i;
   int stateno = pParser->yystack[pParser->yyidx].stateno;
  
-  if( stateno>YY_SHIFT_COUNT
-   || (i = yy_shift_ofst[stateno])==YY_SHIFT_USE_DFLT ){
-    return yy_default[stateno];
-  }
+  if( stateno>=YY_MIN_REDUCE ) return stateno;
+  assert( stateno <= YY_SHIFT_COUNT );
+  i = yy_shift_ofst[stateno];
+  if( i==YY_SHIFT_USE_DFLT ) return yy_default[stateno];
   assert( iLookAhead!=YYNOCODE );
   i += iLookAhead;
   if( i<0 || i>=YY_ACTTAB_COUNT || yy_lookahead[i]!=iLookAhead ){
@@ -499,7 +511,29 @@ static void yyStackOverflow(yyParser *yypParser, YYMINORTYPE *yypMinor){
 }
 
 /*
-** Perform a shift action.
+** Print tracing information for a SHIFT action
+*/
+#ifndef NDEBUG
+static void yyTraceShift(yyParser *yypParser, int yyNewState){
+  if( yyTraceFILE ){
+    int i;
+    if( yyNewState<YYNSTATE ){
+      fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyNewState);
+      fprintf(yyTraceFILE,"%sStack:",yyTracePrompt);
+      for(i=1; i<=yypParser->yyidx; i++)
+        fprintf(yyTraceFILE," %s",yyTokenName[yypParser->yystack[i].major]);
+      fprintf(yyTraceFILE,"\n");
+    }else{
+      fprintf(yyTraceFILE,"%sShift *\n",yyTracePrompt);
+    }
+  }
+}
+#else
+# define yyTraceShift(X,Y)
+#endif
+
+/*
+** Perform a shift action.  Return the number of errors.
 */
 static void yy_shift(
   yyParser *yypParser,          /* The parser to be shifted */
@@ -532,16 +566,7 @@ static void yy_shift(
   yytos->stateno = (YYACTIONTYPE)yyNewState;
   yytos->major = (YYCODETYPE)yyMajor;
   yytos->minor = *yypMinor;
-#ifndef NDEBUG
-  if( yyTraceFILE && yypParser->yyidx>0 ){
-    int i;
-    fprintf(yyTraceFILE,"%sShift %d\n",yyTracePrompt,yyNewState);
-    fprintf(yyTraceFILE,"%sStack:",yyTracePrompt);
-    for(i=1; i<=yypParser->yyidx; i++)
-      fprintf(yyTraceFILE," %s",yyTokenName[yypParser->yystack[i].major]);
-    fprintf(yyTraceFILE,"\n");
-  }
-#endif
+  yyTraceShift(yypParser, yyNewState);
 }
 
 /* The following table contains information about every rule that
@@ -574,8 +599,9 @@ static void yy_reduce(
 #ifndef NDEBUG
   if( yyTraceFILE && yyruleno>=0 
         && yyruleno<(int)(sizeof(yyRuleName)/sizeof(yyRuleName[0])) ){
-    fprintf(yyTraceFILE, "%sReduce [%s].\n", yyTracePrompt,
-      yyRuleName[yyruleno]);
+    yysize = yyRuleInfo[yyruleno].nrhs;
+    fprintf(yyTraceFILE, "%sReduce [%s] -> state %d.\n", yyTracePrompt,
+      yyRuleName[yyruleno], yymsp[-yysize].stateno);
   }
 #endif /* NDEBUG */
 
@@ -613,9 +639,9 @@ static void yy_reduce(
   yysize = yyRuleInfo[yyruleno].nrhs;
   yypParser->yyidx -= yysize;
   yyact = yy_find_reduce_action(yymsp[-yysize].stateno,(YYCODETYPE)yygoto);
-  if( yyact < YYNSTATE ){
-#ifdef NDEBUG
-    /* If we are not debugging and the reduce action popped at least
+  if( yyact <= YY_MAX_SHIFTREDUCE ){
+    if( yyact>YY_MAX_SHIFT ) yyact += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE;
+    /* If the reduce action popped at least
     ** one element off the stack, then we can push the new element back
     ** onto the stack here, and skip the stack overflow test in yy_shift().
     ** That gives a significant speed improvement. */
@@ -625,13 +651,12 @@ static void yy_reduce(
       yymsp->stateno = (YYACTIONTYPE)yyact;
       yymsp->major = (YYCODETYPE)yygoto;
       yymsp->minor = yygotominor;
-    }else
-#endif
-    {
+      yyTraceShift(yypParser, yyact);
+    }else{
       yy_shift(yypParser,yyact,yygoto,&yygotominor);
     }
   }else{
-    assert( yyact == YYNSTATE + YYNRULE + 1 );
+    assert( yyact == YY_ACCEPT_ACTION );
     yy_accept(yypParser);
   }
 }
@@ -755,12 +780,13 @@ void Parse(
 
   do{
     yyact = yy_find_shift_action(yypParser,(YYCODETYPE)yymajor);
-    if( yyact<YYNSTATE ){
+    if( yyact <= YY_MAX_SHIFTREDUCE ){
+      if( yyact > YY_MAX_SHIFT ) yyact += YY_MIN_REDUCE - YY_MIN_SHIFTREDUCE;
       yy_shift(yypParser,yyact,yymajor,&yyminorunion);
       yypParser->yyerrcnt--;
       yymajor = YYNOCODE;
-    }else if( yyact < YYNSTATE + YYNRULE ){
-      yy_reduce(yypParser,yyact-YYNSTATE);
+    }else if( yyact <= YY_MAX_REDUCE ){
+      yy_reduce(yypParser,yyact-YY_MIN_REDUCE);
     }else{
       assert( yyact == YY_ERROR_ACTION );
 #ifdef YYERRORSYMBOL
@@ -810,7 +836,7 @@ void Parse(
           yymx != YYERRORSYMBOL &&
           (yyact = yy_find_reduce_action(
                         yypParser->yystack[yypParser->yyidx].stateno,
-                        YYERRORSYMBOL)) >= YYNSTATE
+                        YYERRORSYMBOL)) >= YY_MIN_REDUCE
         ){
           yy_pop_parser_stack(yypParser);
         }
@@ -860,5 +886,10 @@ void Parse(
 #endif
     }
   }while( yymajor!=YYNOCODE && yypParser->yyidx>=0 );
+#ifndef NDEBUG
+  if( yyTraceFILE ){
+    fprintf(yyTraceFILE,"%sReturn\n",yyTracePrompt);
+  }
+#endif
   return;
 }
diff --git a/src/loadext.c b/src/loadext.c
index 1d398c54c..b4b981e54 100644
--- a/src/loadext.c
+++ b/src/loadext.c
@@ -407,7 +407,10 @@ static const sqlite3_api_routines sqlite3Apis = {
   (sqlite3_value*(*)(const sqlite3_value*))sqlite3_value_dup,
   sqlite3_value_free,
   sqlite3_result_zeroblob64,
-  sqlite3_bind_zeroblob64
+  sqlite3_bind_zeroblob64,
+  /* Version 3.8.12 and later */
+  sqlite3_value_subtype,
+  sqlite3_result_subtype
 };
 
 /*
diff --git a/src/malloc.c b/src/malloc.c
index 23d7598ae..f20eb6e79 100644
--- a/src/malloc.c
+++ b/src/malloc.c
@@ -45,7 +45,7 @@ typedef struct ScratchFreeslot {
 */
 static SQLITE_WSD struct Mem0Global {
   sqlite3_mutex *mutex;         /* Mutex to serialize access */
-  sqlite3_int64 alarmThreshold;  /* The soft heap limit */
+  sqlite3_int64 alarmThreshold; /* The soft heap limit */
 
   /*
   ** Pointers to the end of sqlite3GlobalConfig.pScratch memory
@@ -73,59 +73,20 @@ sqlite3_mutex *sqlite3MallocMutex(void){
   return mem0.mutex;
 }
 
-/*
-** Return the amount of memory currently in use.
-*/
-static sqlite3_int64 memInUse(void){
-  assert( sqlite3_mutex_held(mem0.mutex) );
-  return sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
-}
-
-/*
-** Called when the soft heap limit is exceeded for an allocation
-** of nBytes.
-*/
-#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
-static void sqlite3HeapLimitExceeded(int nByte){
-  sqlite3_int64 excess = memInUse() + nByte - mem0.alarmThreshold;
-  sqlite3_mutex_leave(mem0.mutex);
-  sqlite3_release_memory((int)(excess & 0x7fffffff));
-  sqlite3_mutex_enter(mem0.mutex);
-}
-#else
-# define sqlite3HeapLimitExceeded(X)  /* no-op */
-#endif
-
-/*
-** Check to see if increasing the total memory usage by nNew bytes
-** will exceed the soft heap limit.  
-**
-** If the soft heap limit is exceeded, set the mem0.nearlyFull flag
-** and invoke sqlite3HeapLimitExceeded() to try to free up some
-** memory.
-*/
-static void sqlite3CheckSoftHeapLimit(int nNew){
-  assert( sqlite3_mutex_held(mem0.mutex) );
-  if( mem0.alarmThreshold>0 ){
-    if( mem0.alarmThreshold-nNew >= memInUse() ){
-      mem0.nearlyFull = 1;
-      sqlite3HeapLimitExceeded(nNew);
-    }else{
-      mem0.nearlyFull = 0;
-    }
-  }
-}
-
 #ifndef SQLITE_OMIT_DEPRECATED
 /*
-** Deprecated external interface.  First deprecated 2007-11-05.  Changed
-** into a no-op on 2015-09-02.
+** Deprecated external interface.  It used to set an alarm callback
+** that was invoked when memory usage grew too large.  Now it is a
+** no-op.
 */
 int sqlite3_memory_alarm(
   void(*xCallback)(void *pArg, sqlite3_int64 used,int N),
   void *pArg,
   sqlite3_int64 iThreshold
 ){
+  (void)xCallback;
+  (void)pArg;
+  (void)iThreshold;
   return SQLITE_OK;
 }
 #endif
@@ -136,20 +97,24 @@ int sqlite3_memory_alarm(
 */
 sqlite3_int64 sqlite3_soft_heap_limit64(sqlite3_int64 n){
   sqlite3_int64 priorLimit;
+  sqlite3_int64 excess;
+  sqlite3_int64 nUsed;
 #ifndef SQLITE_OMIT_AUTOINIT
   int rc = sqlite3_initialize();
   if( rc ) return -1;
 #endif
   sqlite3_mutex_enter(mem0.mutex);
   priorLimit = mem0.alarmThreshold;
-  if( n>0 ){
-    mem0.alarmThreshold = n;
-    sqlite3CheckSoftHeapLimit(0);
-  }else if( n==0 ){
-    mem0.alarmThreshold = 0;
-    mem0.nearlyFull = 0;
+  if( n<0 ){
+    sqlite3_mutex_leave(mem0.mutex);
+    return priorLimit;
   }
+  mem0.alarmThreshold = n;
+  nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+  mem0.nearlyFull = (n>0 && n<=nUsed);
   sqlite3_mutex_leave(mem0.mutex);
+  excess = sqlite3_memory_used() - n;
+  if( excess>0 ) sqlite3_release_memory((int)(excess & 0x7fffffff));
   return priorLimit;
 }
 void sqlite3_soft_heap_limit(int n){
@@ -241,6 +206,16 @@ sqlite3_int64 sqlite3_memory_highwater(int resetFlag){
 }
 
 /*
+** Trigger the alarm 
+*/
+static void sqlite3MallocAlarm(int nByte){
+  if( mem0.alarmThreshold<=0 ) return;
+  sqlite3_mutex_leave(mem0.mutex);
+  sqlite3_release_memory(nByte);
+  sqlite3_mutex_enter(mem0.mutex);
+}
+
+/*
 ** Do a memory allocation with statistics and alarms.  Assume the
 ** lock is already held.
 */
@@ -250,11 +225,19 @@ static int mallocWithAlarm(int n, void **pp){
   assert( sqlite3_mutex_held(mem0.mutex) );
   nFull = sqlite3GlobalConfig.m.xRoundup(n);
   sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, n);
-  sqlite3CheckSoftHeapLimit(nFull);
+  if( mem0.alarmThreshold>0 ){
+    sqlite3_int64 nUsed = sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED);
+    if( nUsed >= mem0.alarmThreshold - nFull ){
+      mem0.nearlyFull = 1;
+      sqlite3MallocAlarm(nFull);
+    }else{
+      mem0.nearlyFull = 0;
+    }
+  }
   p = sqlite3GlobalConfig.m.xMalloc(nFull);
 #ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
-  if( p==0 && mem0.alarmThreshold ){
-    sqlite3HeapLimitExceeded(nFull);
+  if( p==0 && mem0.alarmThreshold>0 ){
+    sqlite3MallocAlarm(nFull);
     p = sqlite3GlobalConfig.m.xMalloc(nFull);
   }
 #endif
@@ -537,14 +520,15 @@ void *sqlite3Realloc(void *pOld, u64 nBytes){
     sqlite3_mutex_enter(mem0.mutex);
     sqlite3StatusSet(SQLITE_STATUS_MALLOC_SIZE, (int)nBytes);
     nDiff = nNew - nOld;
-    sqlite3CheckSoftHeapLimit(nDiff);
+    if( sqlite3StatusValue(SQLITE_STATUS_MEMORY_USED) >= 
+          mem0.alarmThreshold-nDiff ){
+      sqlite3MallocAlarm(nDiff);
+    }
     pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
-#ifdef SQLITE_ENABLE_MEMORY_MANAGEMENT
-    if( pNew==0 && mem0.alarmThreshold ){
-      sqlite3HeapLimitExceeded((int)nBytes);
+    if( pNew==0 && mem0.alarmThreshold>0 ){
+      sqlite3MallocAlarm((int)nBytes);
       pNew = sqlite3GlobalConfig.m.xRealloc(pOld, nNew);
     }
-#endif
     if( pNew ){
       nNew = sqlite3MallocSize(pNew);
       sqlite3StatusUp(SQLITE_STATUS_MEMORY_USED, nNew-nOld);
diff --git a/src/mutex.c b/src/mutex.c
index 64efd3b05..6f1bc9767 100644
--- a/src/mutex.c
+++ b/src/mutex.c
@@ -22,7 +22,7 @@
 ** allocate a mutex while the system is uninitialized.
 */
 static SQLITE_WSD int mutexIsInit = 0;
-#endif /* SQLITE_DEBUG */
+#endif /* SQLITE_DEBUG && !defined(SQLITE_MUTEX_OMIT) */
 
 
 #ifndef SQLITE_MUTEX_OMIT
@@ -53,8 +53,10 @@ int sqlite3MutexInit(void){
     pTo->xMutexLeave = pFrom->xMutexLeave;
     pTo->xMutexHeld = pFrom->xMutexHeld;
     pTo->xMutexNotheld = pFrom->xMutexNotheld;
+    sqlite3MemoryBarrier();
     pTo->xMutexAlloc = pFrom->xMutexAlloc;
   }
+  assert( sqlite3GlobalConfig.mutex.xMutexInit );
   rc = sqlite3GlobalConfig.mutex.xMutexInit();
 
 #ifdef SQLITE_DEBUG
@@ -89,6 +91,7 @@ sqlite3_mutex *sqlite3_mutex_alloc(int id){
   if( id<=SQLITE_MUTEX_RECURSIVE && sqlite3_initialize() ) return 0;
   if( id>SQLITE_MUTEX_RECURSIVE && sqlite3MutexInit() ) return 0;
 #endif
+  assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
   return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
 }
 
@@ -97,6 +100,7 @@ sqlite3_mutex *sqlite3MutexAlloc(int id){
     return 0;
   }
   assert( GLOBAL(int, mutexIsInit) );
+  assert( sqlite3GlobalConfig.mutex.xMutexAlloc );
   return sqlite3GlobalConfig.mutex.xMutexAlloc(id);
 }
 
@@ -105,6 +109,7 @@ sqlite3_mutex *sqlite3MutexAlloc(int id){
 */
 void sqlite3_mutex_free(sqlite3_mutex *p){
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexFree );
     sqlite3GlobalConfig.mutex.xMutexFree(p);
   }
 }
@@ -115,6 +120,7 @@ void sqlite3_mutex_free(sqlite3_mutex *p){
 */
 void sqlite3_mutex_enter(sqlite3_mutex *p){
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexEnter );
     sqlite3GlobalConfig.mutex.xMutexEnter(p);
   }
 }
@@ -126,6 +132,7 @@ void sqlite3_mutex_enter(sqlite3_mutex *p){
 int sqlite3_mutex_try(sqlite3_mutex *p){
   int rc = SQLITE_OK;
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexTry );
     return sqlite3GlobalConfig.mutex.xMutexTry(p);
   }
   return rc;
@@ -139,6 +146,7 @@ int sqlite3_mutex_try(sqlite3_mutex *p){
 */
 void sqlite3_mutex_leave(sqlite3_mutex *p){
   if( p ){
+    assert( sqlite3GlobalConfig.mutex.xMutexLeave );
     sqlite3GlobalConfig.mutex.xMutexLeave(p);
   }
 }
@@ -149,9 +157,11 @@ void sqlite3_mutex_leave(sqlite3_mutex *p){
 ** intended for use inside assert() statements.
 */
 int sqlite3_mutex_held(sqlite3_mutex *p){
+  assert( p==0 || sqlite3GlobalConfig.mutex.xMutexHeld );
   return p==0 || sqlite3GlobalConfig.mutex.xMutexHeld(p);
 }
 int sqlite3_mutex_notheld(sqlite3_mutex *p){
+  assert( p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld );
   return p==0 || sqlite3GlobalConfig.mutex.xMutexNotheld(p);
 }
 #endif
diff --git a/src/mutex_unix.c b/src/mutex_unix.c
index 0a493fa6a..cebb96c90 100644
--- a/src/mutex_unix.c
+++ b/src/mutex_unix.c
@@ -81,6 +81,17 @@ static int pthreadMutexNotheld(sqlite3_mutex *p){
 #endif
 
 /*
+** Try to provide a memory barrier operation, needed for initialization only.
+*/
+void sqlite3MemoryBarrier(void){
+#if defined(SQLITE_MEMORY_BARRIER)
+  SQLITE_MEMORY_BARRIER;
+#elif defined(__GNUC__) && GCC_VERSION>=4001000
+  __sync_synchronize();
+#endif
+}
+
+/*
 ** Initialize and deinitialize the mutex subsystem.
 */
 static int pthreadMutexInit(void){ return SQLITE_OK; }
diff --git a/src/mutex_w32.c b/src/mutex_w32.c
index fc943acaa..90be07db2 100644
--- a/src/mutex_w32.c
+++ b/src/mutex_w32.c
@@ -78,6 +78,19 @@ static int winMutexNotheld(sqlite3_mutex *p){
 #endif
 
 /*
+** Try to provide a memory barrier operation, needed for initialization only.
+*/
+void sqlite3MemoryBarrier(void){
+#if defined(SQLITE_MEMORY_BARRIER)
+  SQLITE_MEMORY_BARRIER;
+#elif defined(__GNUC__)
+  __sync_synchronize();
+#else
+  MemoryBarrier();
+#endif
+}
+
+/*
 ** Initialize and deinitialize the mutex subsystem.
 */
 static sqlite3_mutex winMutex_staticMutexes[] = {
diff --git a/src/pager.c b/src/pager.c
index 060edb8d1..2f7c330d6 100644
--- a/src/pager.c
+++ b/src/pager.c
@@ -647,7 +647,7 @@ struct Pager {
   u8 doNotSpill;              /* Do not spill the cache when non-zero */
   u8 subjInMemory;            /* True to use in-memory sub-journals */
   u8 bUseFetch;               /* True to use xFetch() */
-  u8 hasBeenUsed;             /* True if any content previously read */
+  u8 hasHeldSharedLock;       /* True if a shared lock has ever been held */
   Pgno dbSize;                /* Number of pages in the database */
   Pgno dbOrigSize;            /* dbSize before the current transaction */
   Pgno dbFileSize;            /* Number of pages in the database file */
@@ -5097,10 +5097,10 @@ int sqlite3PagerSharedLock(Pager *pPager){
       );
     }
 
-    if( !pPager->tempFile && pPager->hasBeenUsed ){
+    if( !pPager->tempFile && pPager->hasHeldSharedLock ){
       /* The shared-lock has just been acquired then check to
       ** see if the database has been modified.  If the database has changed,
-      ** flush the cache.  The pPager->hasBeenUsed flag prevents this from
+      ** flush the cache.  The hasHeldSharedLock flag prevents this from
       ** occurring on the very first access to a file, in order to save a
       ** single unnecessary sqlite3OsRead() call at the start-up.
       **
@@ -5170,6 +5170,7 @@ int sqlite3PagerSharedLock(Pager *pPager){
     assert( pPager->eState==PAGER_OPEN );
   }else{
     pPager->eState = PAGER_READER;
+    pPager->hasHeldSharedLock = 1;
   }
   return rc;
 }
@@ -5253,21 +5254,25 @@ int sqlite3PagerAcquire(
   ** page 1 if there is no write-transaction open or the ACQUIRE_READONLY
   ** flag was specified by the caller. And so long as the db is not a 
   ** temporary or in-memory database.  */
-  const int bMmapOk = (pgno!=1 && USEFETCH(pPager)
+  const int bMmapOk = (pgno>1 && USEFETCH(pPager)
    && (pPager->eState==PAGER_READER || (flags & PAGER_GET_READONLY))
 #ifdef SQLITE_HAS_CODEC
    && pPager->xCodec==0
 #endif
   );
 
+  /* Optimization note:  Adding the "pgno<=1" term before "pgno==0" here
+  ** allows the compiler optimizer to reuse the results of the "pgno>1"
+  ** test in the previous statement, and avoid testing pgno==0 in the
+  ** common case where pgno is large. */
+  if( pgno<=1 && pgno==0 ){
+    return SQLITE_CORRUPT_BKPT;
+  }
   assert( pPager->eState>=PAGER_READER );
   assert( assert_pager_state(pPager) );
   assert( noContent==0 || bMmapOk==0 );
 
-  if( pgno==0 ){
-    return SQLITE_CORRUPT_BKPT;
-  }
-  pPager->hasBeenUsed = 1;
+  assert( pPager->hasHeldSharedLock==1 );
 
   /* If the pager is in the error state, return an error immediately. 
   ** Otherwise, request the page from the PCache layer. */
@@ -5422,7 +5427,7 @@ DbPage *sqlite3PagerLookup(Pager *pPager, Pgno pgno){
   assert( pgno!=0 );
   assert( pPager->pPCache!=0 );
   pPage = sqlite3PcacheFetch(pPager->pPCache, pgno, 0);
-  assert( pPage==0 || pPager->hasBeenUsed );
+  assert( pPage==0 || pPager->hasHeldSharedLock );
   if( pPage==0 ) return 0;
   return sqlite3PcacheFetchFinish(pPager->pPCache, pgno, pPage);
 }
@@ -6389,7 +6394,7 @@ u8 sqlite3PagerIsreadonly(Pager *pPager){
 
 #ifdef SQLITE_DEBUG
 /*
-** Return the number of references to the pager.
+** Return the sum of the reference counts for all pages held by pPager.
 */
 int sqlite3PagerRefcount(Pager *pPager){
   return sqlite3PcacheRefCount(pPager->pPCache);
diff --git a/src/pcache.c b/src/pcache.c
index 58c05ac2a..e39262cb8 100644
--- a/src/pcache.c
+++ b/src/pcache.c
@@ -19,7 +19,7 @@
 struct PCache {
   PgHdr *pDirty, *pDirtyTail;         /* List of dirty pages in LRU order */
   PgHdr *pSynced;                     /* Last synced page in dirty page list */
-  int nRef;                           /* Number of referenced pages */
+  int nRefSum;                        /* Sum of ref counts over all pages */
   int szCache;                        /* Configured cache size */
   int szPage;                         /* Size of every page in this cache */
   int szExtra;                        /* Size of extra space for each page */
@@ -184,7 +184,7 @@ int sqlite3PcacheOpen(
 ** are no outstanding page references when this function is called.
 */
 int sqlite3PcacheSetPageSize(PCache *pCache, int szPage){
-  assert( pCache->nRef==0 && pCache->pDirty==0 );
+  assert( pCache->nRefSum==0 && pCache->pDirty==0 );
   if( pCache->szPage ){
     sqlite3_pcache *pNew;
     pNew = sqlite3GlobalConfig.pcache2.xCreate(
@@ -351,9 +351,7 @@ PgHdr *sqlite3PcacheFetchFinish(
   if( !pPgHdr->pPage ){
     return pcacheFetchFinishWithInit(pCache, pgno, pPage);
   }
-  if( 0==pPgHdr->nRef ){
-    pCache->nRef++;
-  }
+  pCache->nRefSum++;
   pPgHdr->nRef++;
   return pPgHdr;
 }
@@ -364,9 +362,8 @@ PgHdr *sqlite3PcacheFetchFinish(
 */
 void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){
   assert( p->nRef>0 );
-  p->nRef--;
-  if( p->nRef==0 ){
-    p->pCache->nRef--;
+  p->pCache->nRefSum--;
+  if( (--p->nRef)==0 ){
     if( p->flags&PGHDR_CLEAN ){
       pcacheUnpin(p);
     }else if( p->pDirtyPrev!=0 ){
@@ -382,6 +379,7 @@ void SQLITE_NOINLINE sqlite3PcacheRelease(PgHdr *p){
 void sqlite3PcacheRef(PgHdr *p){
   assert(p->nRef>0);
   p->nRef++;
+  p->pCache->nRefSum++;
 }
 
 /*
@@ -394,7 +392,7 @@ void sqlite3PcacheDrop(PgHdr *p){
   if( p->flags&PGHDR_DIRTY ){
     pcacheManageDirtyList(p, PCACHE_DIRTYLIST_REMOVE);
   }
-  p->pCache->nRef--;
+  p->pCache->nRefSum--;
   sqlite3GlobalConfig.pcache2.xUnpin(p->pCache->pCache, p->pPage, 1);
 }
 
@@ -490,11 +488,11 @@ void sqlite3PcacheTruncate(PCache *pCache, Pgno pgno){
         sqlite3PcacheMakeClean(p);
       }
     }
-    if( pgno==0 && pCache->nRef ){
+    if( pgno==0 && pCache->nRefSum ){
       sqlite3_pcache_page *pPage1;
       pPage1 = sqlite3GlobalConfig.pcache2.xFetch(pCache->pCache,1,0);
       if( ALWAYS(pPage1) ){  /* Page 1 is always available in cache, because
-                             ** pCache->nRef>0 */
+                             ** pCache->nRefSum>0 */
         memset(pPage1->pBuf, 0, pCache->szPage);
         pgno = 1;
       }
@@ -600,10 +598,13 @@ PgHdr *sqlite3PcacheDirtyList(PCache *pCache){
 }
 
 /* 
-** Return the total number of referenced pages held by the cache.
+** Return the total number of references to all pages held by the cache.
+**
+** This is not the total number of pages referenced, but the sum of the
+** reference count for all pages.
 */
 int sqlite3PcacheRefCount(PCache *pCache){
-  return pCache->nRef;
+  return pCache->nRefSum;
 }
 
 /*
diff --git a/src/pcache1.c b/src/pcache1.c
index 18df8c87d..00a0205f5 100644
--- a/src/pcache1.c
+++ b/src/pcache1.c
@@ -87,6 +87,24 @@ typedef struct PgHdr1 PgHdr1;
 typedef struct PgFreeslot PgFreeslot;
 typedef struct PGroup PGroup;
 
+/*
+** Each cache entry is represented by an instance of the following 
+** structure. Unless SQLITE_PCACHE_SEPARATE_HEADER is defined, a buffer of
+** PgHdr1.pCache->szPage bytes is allocated directly before this structure 
+** in memory.
+*/
+struct PgHdr1 {
+  sqlite3_pcache_page page;      /* Base class. Must be first. pBuf & pExtra */
+  unsigned int iKey;             /* Key value (page number) */
+  u8 isPinned;                   /* Page in use, not on the LRU list */
+  u8 isBulkLocal;                /* This page from bulk local storage */
+  u8 isAnchor;                   /* This is the PGroup.lru element */
+  PgHdr1 *pNext;                 /* Next in hash table chain */
+  PCache1 *pCache;               /* Cache that currently owns this page */
+  PgHdr1 *pLruNext;              /* Next in LRU list of unpinned pages */
+  PgHdr1 *pLruPrev;              /* Previous in LRU list of unpinned pages */
+};
+
 /* Each page cache (or PCache) belongs to a PGroup.  A PGroup is a set 
 ** of one or more PCaches that are able to recycle each other's unpinned
 ** pages when they are under memory pressure.  A PGroup is an instance of
@@ -115,7 +133,7 @@ struct PGroup {
   unsigned int nMinPage;         /* Sum of nMin for purgeable caches */
   unsigned int mxPinned;         /* nMaxpage + 10 - nMinPage */
   unsigned int nCurrentPage;     /* Number of purgeable pages allocated */
-  PgHdr1 *pLruHead, *pLruTail;   /* LRU list of unpinned pages */
+  PgHdr1 lru;                    /* The beginning and end of the LRU list */
 };
 
 /* Each page cache is an instance of the following object.  Every
@@ -154,23 +172,6 @@ struct PCache1 {
 };
 
 /*
-** Each cache entry is represented by an instance of the following 
-** structure. Unless SQLITE_PCACHE_SEPARATE_HEADER is defined, a buffer of
-** PgHdr1.pCache->szPage bytes is allocated directly before this structure 
-** in memory.
-*/
-struct PgHdr1 {
-  sqlite3_pcache_page page;
-  unsigned int iKey;             /* Key value (page number) */
-  u8 isPinned;                   /* Page in use, not on the LRU list */
-  u8 isBulkLocal;                /* This page from bulk local storage */
-  PgHdr1 *pNext;                 /* Next in hash table chain */
-  PCache1 *pCache;               /* Cache that currently owns this page */
-  PgHdr1 *pLruNext;              /* Next in LRU list of unpinned pages */
-  PgHdr1 *pLruPrev;              /* Previous in LRU list of unpinned pages */
-};
-
-/*
 ** Free slots in the allocator used to divide up the global page cache
 ** buffer provided using the SQLITE_CONFIG_PAGECACHE mechanism.
 */
@@ -230,6 +231,7 @@ static SQLITE_WSD struct PCacheGlobal {
 /******************************************************************************/
 /******** Page Allocation/SQLITE_CONFIG_PCACHE Related Functions **************/
 
+
 /*
 ** This function is called during initialization if a static buffer is 
 ** supplied to use for the page-cache by passing the SQLITE_CONFIG_PAGECACHE
@@ -289,6 +291,7 @@ static int pcache1InitBulk(PCache1 *pCache){
       pX->page.pBuf = zBulk;
       pX->page.pExtra = &pX[1];
       pX->isBulkLocal = 1;
+      pX->isAnchor = 0;
       pX->pNext = pCache->pFree;
       pCache->pFree = pX;
       zBulk += pCache->szAlloc;
@@ -431,6 +434,7 @@ static PgHdr1 *pcache1AllocPage(PCache1 *pCache, int benignMalloc){
     p->page.pBuf = pPg;
     p->page.pExtra = &p[1];
     p->isBulkLocal = 0;
+    p->isAnchor = 0;
   }
   if( pCache->bPurgeable ){
     pCache->pGroup->nCurrentPage++;
@@ -557,22 +561,16 @@ static PgHdr1 *pcache1PinPage(PgHdr1 *pPage){
   assert( pPage!=0 );
   assert( pPage->isPinned==0 );
   pCache = pPage->pCache;
-  assert( pPage->pLruNext || pPage==pCache->pGroup->pLruTail );
-  assert( pPage->pLruPrev || pPage==pCache->pGroup->pLruHead );
+  assert( pPage->pLruNext );
+  assert( pPage->pLruPrev );
   assert( sqlite3_mutex_held(pCache->pGroup->mutex) );
-  if( pPage->pLruPrev ){
-    pPage->pLruPrev->pLruNext = pPage->pLruNext;
-  }else{
-    pCache->pGroup->pLruHead = pPage->pLruNext;
-  }
-  if( pPage->pLruNext ){
-    pPage->pLruNext->pLruPrev = pPage->pLruPrev;
-  }else{
-    pCache->pGroup->pLruTail = pPage->pLruPrev;
-  }
+  pPage->pLruPrev->pLruNext = pPage->pLruNext;
+  pPage->pLruNext->pLruPrev = pPage->pLruPrev;
   pPage->pLruNext = 0;
   pPage->pLruPrev = 0;
   pPage->isPinned = 1;
+  assert( pPage->isAnchor==0 );
+  assert( pCache->pGroup->lru.isAnchor==1 );
   pCache->nRecyclable--;
   return pPage;
 }
@@ -605,9 +603,11 @@ static void pcache1RemoveFromHash(PgHdr1 *pPage, int freeFlag){
 */
 static void pcache1EnforceMaxPage(PCache1 *pCache){
   PGroup *pGroup = pCache->pGroup;
+  PgHdr1 *p;
   assert( sqlite3_mutex_held(pGroup->mutex) );
-  while( pGroup->nCurrentPage>pGroup->nMaxPage && pGroup->pLruTail ){
-    PgHdr1 *p = pGroup->pLruTail;
+  while( pGroup->nCurrentPage>pGroup->nMaxPage
+      && (p=pGroup->lru.pLruPrev)->isAnchor==0
+  ){
     assert( p->pCache->pGroup==pGroup );
     assert( p->isPinned==0 );
     pcache1PinPage(p);
@@ -741,6 +741,10 @@ static sqlite3_pcache *pcache1Create(int szPage, int szExtra, int bPurgeable){
     }else{
       pGroup = &pcache1.grp;
     }
+    if( pGroup->lru.isAnchor==0 ){
+      pGroup->lru.isAnchor = 1;
+      pGroup->lru.pLruPrev = pGroup->lru.pLruNext = &pGroup->lru;
+    }
     pCache->pGroup = pGroup;
     pCache->szPage = szPage;
     pCache->szExtra = szExtra;
@@ -848,11 +852,11 @@ static SQLITE_NOINLINE PgHdr1 *pcache1FetchStage2(
 
   /* Step 4. Try to recycle a page. */
   if( pCache->bPurgeable
-   && pGroup->pLruTail
+   && !pGroup->lru.pLruPrev->isAnchor
    && ((pCache->nPage+1>=pCache->nMax) || pcache1UnderMemoryPressure(pCache))
   ){
     PCache1 *pOther;
-    pPage = pGroup->pLruTail;
+    pPage = pGroup->lru.pLruPrev;
     assert( pPage->isPinned==0 );
     pcache1RemoveFromHash(pPage, 0);
     pcache1PinPage(pPage);
@@ -961,7 +965,10 @@ static PgHdr1 *pcache1FetchNoMutex(
   pPage = pCache->apHash[iKey % pCache->nHash];
   while( pPage && pPage->iKey!=iKey ){ pPage = pPage->pNext; }
 
-  /* Step 2: Abort if no existing page is found and createFlag is 0 */
+  /* Step 2: If the page was found in the hash table, then return it.
+  ** If the page was not in the hash table and createFlag is 0, abort.
+  ** Otherwise (page not in hash and createFlag!=0) continue with
+  ** subsequent steps to try to create the page. */
   if( pPage ){
     if( !pPage->isPinned ){
       return pcache1PinPage(pPage);
@@ -1038,21 +1045,16 @@ static void pcache1Unpin(
   ** part of the PGroup LRU list.
   */
   assert( pPage->pLruPrev==0 && pPage->pLruNext==0 );
-  assert( pGroup->pLruHead!=pPage && pGroup->pLruTail!=pPage );
   assert( pPage->isPinned==1 );
 
   if( reuseUnlikely || pGroup->nCurrentPage>pGroup->nMaxPage ){
     pcache1RemoveFromHash(pPage, 1);
   }else{
     /* Add the page to the PGroup LRU list. */
-    if( pGroup->pLruHead ){
-      pGroup->pLruHead->pLruPrev = pPage;
-      pPage->pLruNext = pGroup->pLruHead;
-      pGroup->pLruHead = pPage;
-    }else{
-      pGroup->pLruTail = pPage;
-      pGroup->pLruHead = pPage;
-    }
+    PgHdr1 **ppFirst = &pGroup->lru.pLruNext;
+    pPage->pLruPrev = &pGroup->lru;
+    (pPage->pLruNext = *ppFirst)->pLruPrev = pPage;
+    *ppFirst = pPage;
     pCache->nRecyclable++;
     pPage->isPinned = 0;
   }
@@ -1190,7 +1192,10 @@ int sqlite3PcacheReleaseMemory(int nReq){
   if( sqlite3GlobalConfig.nPage==0 ){
     PgHdr1 *p;
     pcache1EnterMutex(&pcache1.grp);
-    while( (nReq<0 || nFree<nReq) && ((p=pcache1.grp.pLruTail)!=0) ){
+    while( (nReq<0 || nFree<nReq)
+       &&  (p=pcache1.grp.lru.pLruPrev)!=0
+       &&  p->isAnchor==0
+    ){
       nFree += pcache1MemSize(p->page.pBuf);
 #ifdef SQLITE_PCACHE_SEPARATE_HEADER
       nFree += sqlite3MemSize(p);
@@ -1218,7 +1223,7 @@ void sqlite3PcacheStats(
 ){
   PgHdr1 *p;
   int nRecyclable = 0;
-  for(p=pcache1.grp.pLruHead; p; p=p->pLruNext){
+  for(p=pcache1.grp.lru.pLruNext; p && !p->isAnchor; p=p->pLruNext){
     assert( p->isPinned==0 );
     nRecyclable++;
   }
diff --git a/src/resolve.c b/src/resolve.c
index 04fa8429a..2c4212ba7 100644
--- a/src/resolve.c
+++ b/src/resolve.c
@@ -45,30 +45,6 @@ static void incrAggFunctionDepth(Expr *pExpr, int N){
 ** Turn the pExpr expression into an alias for the iCol-th column of the
 ** result set in pEList.
 **
-** If the result set column is a simple column reference, then this routine
-** makes an exact copy.  But for any other kind of expression, this
-** routine make a copy of the result set column as the argument to the
-** TK_AS operator.  The TK_AS operator causes the expression to be
-** evaluated just once and then reused for each alias.
-**
-** The reason for suppressing the TK_AS term when the expression is a simple
-** column reference is so that the column reference will be recognized as
-** usable by indices within the WHERE clause processing logic. 
-**
-** The TK_AS operator is inhibited if zType[0]=='G'.  This means
-** that in a GROUP BY clause, the expression is evaluated twice.  Hence:
-**
-**     SELECT random()%5 AS x, count(*) FROM tab GROUP BY x
-**
-** Is equivalent to:
-**
-**     SELECT random()%5 AS x, count(*) FROM tab GROUP BY random()%5
-**
-** The result of random()%5 in the GROUP BY clause is probably different
-** from the result in the result-set.  On the other hand Standard SQL does
-** not allow the GROUP BY clause to contain references to result-set columns.
-** So this should never come up in well-formed queries.
-**
 ** If the reference is followed by a COLLATE operator, then make sure
 ** the COLLATE operator is preserved.  For example:
 **
@@ -102,19 +78,11 @@ static void resolveAlias(
   db = pParse->db;
   pDup = sqlite3ExprDup(db, pOrig, 0);
   if( pDup==0 ) return;
-  if( pOrig->op!=TK_COLUMN && zType[0]!='G' ){
-    incrAggFunctionDepth(pDup, nSubquery);
-    pDup = sqlite3PExpr(pParse, TK_AS, pDup, 0, 0);
-    if( pDup==0 ) return;
-    ExprSetProperty(pDup, EP_Skip);
-    if( pEList->a[iCol].u.x.iAlias==0 ){
-      pEList->a[iCol].u.x.iAlias = (u16)(++pParse->nAlias);
-    }
-    pDup->iTable = pEList->a[iCol].u.x.iAlias;
-  }
+  if( zType[0]!='G' ) incrAggFunctionDepth(pDup, nSubquery);
   if( pExpr->op==TK_COLLATE ){
     pDup = sqlite3ExprAddCollateString(pParse, pDup, pExpr->u.zToken);
   }
+  ExprSetProperty(pDup, EP_Alias);
 
   /* Before calling sqlite3ExprDelete(), set the EP_Static flag. This 
   ** prevents ExprDelete() from deleting the Expr structure itself,
@@ -506,7 +474,7 @@ static int lookupName(
 lookupname_end:
   if( cnt==1 ){
     assert( pNC!=0 );
-    if( pExpr->op!=TK_AS ){
+    if( !ExprHasProperty(pExpr, EP_Alias) ){
       sqlite3AuthRead(pParse, pExpr, pSchema, pNC->pSrcList);
     }
     /* Increment the nRef value on all name contexts from TopNC up to
@@ -547,36 +515,25 @@ Expr *sqlite3CreateColumnExpr(sqlite3 *db, SrcList *pSrc, int iSrc, int iCol){
 }
 
 /*
-** Report an error that an expression is not valid for a partial index WHERE
-** clause.
+** Report an error that an expression is not valid for some set of
+** pNC->ncFlags values determined by validMask.
 */
-static void notValidPartIdxWhere(
+static void notValid(
   Parse *pParse,       /* Leave error message here */
   NameContext *pNC,    /* The name context */
-  const char *zMsg     /* Type of error */
+  const char *zMsg,    /* Type of error */
+  int validMask        /* Set of contexts for which prohibited */
 ){
-  if( (pNC->ncFlags & NC_PartIdx)!=0 ){
-    sqlite3ErrorMsg(pParse, "%s prohibited in partial index WHERE clauses",
-                    zMsg);
-  }
-}
-
+  assert( (validMask&~(NC_IsCheck|NC_PartIdx|NC_IdxExpr))==0 );
+  if( (pNC->ncFlags & validMask)!=0 ){
+    const char *zIn = "partial index WHERE clauses";
+    if( pNC->ncFlags & NC_IdxExpr )      zIn = "index expressions";
 #ifndef SQLITE_OMIT_CHECK
-/*
-** Report an error that an expression is not valid for a CHECK constraint.
-*/
-static void notValidCheckConstraint(
-  Parse *pParse,       /* Leave error message here */
-  NameContext *pNC,    /* The name context */
-  const char *zMsg     /* Type of error */
-){
-  if( (pNC->ncFlags & NC_IsCheck)!=0 ){
-    sqlite3ErrorMsg(pParse,"%s prohibited in CHECK constraints", zMsg);
+    else if( pNC->ncFlags & NC_IsCheck ) zIn = "CHECK constraints";
+#endif
+    sqlite3ErrorMsg(pParse, "%s prohibited in %s", zMsg, zIn);
   }
 }
-#else
-# define notValidCheckConstraint(P,N,M)
-#endif
 
 /*
 ** Expression p should encode a floating point value between 1.0 and 0.0.
@@ -661,6 +618,8 @@ static int resolveExprStep(Walker *pWalker, Expr *pExpr){
       Expr *pRight;
 
       /* if( pSrcList==0 ) break; */
+      notValid(pParse, pNC, "the \".\" operator", NC_IdxExpr);
+      /*notValid(pParse, pNC, "the \".\" operator", NC_PartIdx|NC_IsCheck, 1);*/
       pRight = pExpr->pRight;
       if( pRight->op==TK_ID ){
         zDb = 0;
@@ -690,7 +649,7 @@ static int resolveExprStep(Walker *pWalker, Expr *pExpr){
       u8 enc = ENC(pParse->db);   /* The database encoding */
 
       assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
-      notValidPartIdxWhere(pParse, pNC, "functions");
+      notValid(pParse, pNC, "functions", NC_PartIdx);
       zId = pExpr->u.zToken;
       nId = sqlite3Strlen30(zId);
       pDef = sqlite3FindFunction(pParse->db, zId, nId, n, enc, 0);
@@ -738,9 +697,18 @@ static int resolveExprStep(Walker *pWalker, Expr *pExpr){
           return WRC_Prune;
         }
 #endif
-        if( pDef->funcFlags & SQLITE_FUNC_CONSTANT ){
+        if( pDef->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG) ){
+          /* For the purposes of the EP_ConstFunc flag, date and time
+          ** functions and other functions that change slowly are considered
+          ** constant because they are constant for the duration of one query */
           ExprSetProperty(pExpr,EP_ConstFunc);
         }
+        if( (pDef->funcFlags & SQLITE_FUNC_CONSTANT)==0 ){
+          /* Date/time functions that use 'now', and other functions like
+          ** sqlite_version() that might change over time cannot be used
+          ** in an index. */
+          notValid(pParse, pNC, "non-deterministic functions", NC_IdxExpr);
+        }
       }
       if( is_agg && (pNC->ncFlags & NC_AllowAgg)==0 ){
         sqlite3ErrorMsg(pParse, "misuse of aggregate function %.*s()", nId,zId);
@@ -786,8 +754,7 @@ static int resolveExprStep(Walker *pWalker, Expr *pExpr){
       testcase( pExpr->op==TK_IN );
       if( ExprHasProperty(pExpr, EP_xIsSelect) ){
         int nRef = pNC->nRef;
-        notValidCheckConstraint(pParse, pNC, "subqueries");
-        notValidPartIdxWhere(pParse, pNC, "subqueries");
+        notValid(pParse, pNC, "subqueries", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
         sqlite3WalkSelect(pWalker, pExpr->x.pSelect);
         assert( pNC->nRef>=nRef );
         if( nRef!=pNC->nRef ){
@@ -797,8 +764,7 @@ static int resolveExprStep(Walker *pWalker, Expr *pExpr){
       break;
     }
     case TK_VARIABLE: {
-      notValidCheckConstraint(pParse, pNC, "parameters");
-      notValidPartIdxWhere(pParse, pNC, "parameters");
+      notValid(pParse, pNC, "parameters", NC_IsCheck|NC_PartIdx|NC_IdxExpr);
       break;
     }
   }
@@ -1501,14 +1467,14 @@ void sqlite3ResolveSelectNames(
 void sqlite3ResolveSelfReference(
   Parse *pParse,      /* Parsing context */
   Table *pTab,        /* The table being referenced */
-  int type,           /* NC_IsCheck or NC_PartIdx */
+  int type,           /* NC_IsCheck or NC_PartIdx or NC_IdxExpr */
   Expr *pExpr,        /* Expression to resolve.  May be NULL. */
   ExprList *pList     /* Expression list to resolve.  May be NUL. */
 ){
   SrcList sSrc;                   /* Fake SrcList for pParse->pNewTable */
   NameContext sNC;                /* Name context for pParse->pNewTable */
 
-  assert( type==NC_IsCheck || type==NC_PartIdx );
+  assert( type==NC_IsCheck || type==NC_PartIdx || type==NC_IdxExpr );
   memset(&sNC, 0, sizeof(sNC));
   memset(&sSrc, 0, sizeof(sSrc));
   sSrc.nSrc = 1;
diff --git a/src/shell.c b/src/shell.c
index e04fe784a..e5eb394ea 100644
--- a/src/shell.c
+++ b/src/shell.c
@@ -4252,8 +4252,8 @@ static int process_input(ShellState *p, FILE *in){
       fprintf(stderr, "Error: incomplete SQL: %s\n", zSql);
       errCnt++;
     }
-    free(zSql);
   }
+  free(zSql);
   free(zLine);
   return errCnt>0;
 }
diff --git a/src/sqlite.h.in b/src/sqlite.h.in
index a7d6318e5..7a51ec109 100644
--- a/src/sqlite.h.in
+++ b/src/sqlite.h.in
@@ -124,7 +124,7 @@ extern "C" {
 ** but are associated with the library instead of the header file.  ^(Cautious
 ** programmers might include assert() statements in their application to
 ** verify that values returned by these interfaces match the macros in
-** the header, and thus insure that the application is
+** the header, and thus ensure that the application is
 ** compiled with matching library and header files.
 **
 ** <blockquote><pre>
@@ -374,7 +374,7 @@ typedef int (*sqlite3_callback)(void*,int,char**, char**);
 ** Restrictions:
 **
 ** <ul>
-** <li> The application must insure that the 1st parameter to sqlite3_exec()
+** <li> The application must ensure that the 1st parameter to sqlite3_exec()
 **      is a valid and open [database connection].
 ** <li> The application must not close the [database connection] specified by
 **      the 1st parameter to sqlite3_exec() while sqlite3_exec() is running.
@@ -1367,9 +1367,11 @@ int sqlite3_os_end(void);
 ** applications and so this routine is usually not necessary.  It is
 ** provided to support rare applications with unusual needs.
 **
-** The sqlite3_config() interface is not threadsafe.  The application
-** must insure that no other SQLite interfaces are invoked by other
-** threads while sqlite3_config() is running.  Furthermore, sqlite3_config()
+** <b>The sqlite3_config() interface is not threadsafe. The application
+** must ensure that no other SQLite interfaces are invoked by other
+** threads while sqlite3_config() is running.</b>
+**
+** The sqlite3_config() interface
 ** may only be invoked prior to library initialization using
 ** [sqlite3_initialize()] or after shutdown by [sqlite3_shutdown()].
 ** ^If sqlite3_config() is called after [sqlite3_initialize()] and before
@@ -4358,6 +4360,22 @@ int sqlite3_value_type(sqlite3_value*);
 int sqlite3_value_numeric_type(sqlite3_value*);
 
 /*
+** CAPI3REF: Obtaining SQL Values
+** METHOD: sqlite3_value
+**
+** The sqlite3_value_subtype(V) function returns the subtype for
+** an [application-defined SQL function] argument V.  The subtype
+** information can be used to pass a limited amount of context from
+** one SQL function to another.  Use the [sqlite3_result_subtype()]
+** routine to set the subtype for the return value of an SQL function.
+**
+** SQLite makes no use of subtype itself.  It merely passes the subtype
+** from the result of one [application-defined SQL function] into the
+** input of another.
+*/
+unsigned int sqlite3_value_subtype(sqlite3_value*);
+
+/*
 ** CAPI3REF: Copy And Free SQL Values
 ** METHOD: sqlite3_value
 **
@@ -4656,6 +4674,21 @@ void sqlite3_result_value(sqlite3_context*, sqlite3_value*);
 void sqlite3_result_zeroblob(sqlite3_context*, int n);
 int sqlite3_result_zeroblob64(sqlite3_context*, sqlite3_uint64 n);
 
+
+/*
+** CAPI3REF: Setting The Subtype Of An SQL Function
+** METHOD: sqlite3_context
+**
+** The sqlite3_result_subtype(C,T) function causes the subtype of
+** the result from the [application-defined SQL function] with 
+** [sqlite3_context] C to be the value T.  Only the lower 8 bits 
+** of the subtype T are preserved in current versions of SQLite;
+** higher order bits are discarded.
+** The number of subtype bytes preserved by SQLite might increase
+** in future releases of SQLite.
+*/
+void sqlite3_result_subtype(sqlite3_context*,unsigned int);
+
 /*
 ** CAPI3REF: Define New Collating Sequences
 ** METHOD: sqlite3
@@ -6094,6 +6127,9 @@ int sqlite3_vfs_unregister(sqlite3_vfs*);
 ** <li>  SQLITE_MUTEX_STATIC_APP1
 ** <li>  SQLITE_MUTEX_STATIC_APP2
 ** <li>  SQLITE_MUTEX_STATIC_APP3
+** <li>  SQLITE_MUTEX_STATIC_VFS1
+** <li>  SQLITE_MUTEX_STATIC_VFS2
+** <li>  SQLITE_MUTEX_STATIC_VFS3
 ** </ul>
 **
 ** ^The first two constants (SQLITE_MUTEX_FAST and SQLITE_MUTEX_RECURSIVE)
diff --git a/src/sqlite3ext.h b/src/sqlite3ext.h
index 1525327f4..9b9f610e9 100644
--- a/src/sqlite3ext.h
+++ b/src/sqlite3ext.h
@@ -272,6 +272,9 @@ struct sqlite3_api_routines {
   void (*value_free)(sqlite3_value*);
   int (*result_zeroblob64)(sqlite3_context*,sqlite3_uint64);
   int (*bind_zeroblob64)(sqlite3_stmt*, int, sqlite3_uint64);
+  /* Version 3.8.12 and later */
+  unsigned int (*value_subtype)(sqlite3_value*);
+  void (*result_subtype)(sqlite3_context*,unsigned int);
 };
 
 /*
@@ -285,7 +288,7 @@ struct sqlite3_api_routines {
 ** the API.  So the redefinition macros are only valid if the
 ** SQLITE_CORE macros is undefined.
 */
-#ifndef SQLITE_CORE
+#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
 #define sqlite3_aggregate_context      sqlite3_api->aggregate_context
 #ifndef SQLITE_OMIT_DEPRECATED
 #define sqlite3_aggregate_count        sqlite3_api->aggregate_count
@@ -508,9 +511,12 @@ struct sqlite3_api_routines {
 #define sqlite3_value_free             sqlite3_api->value_free
 #define sqlite3_result_zeroblob64      sqlite3_api->result_zeroblob64
 #define sqlite3_bind_zeroblob64        sqlite3_api->bind_zeroblob64
-#endif /* SQLITE_CORE */
+/* Version 3.8.12 and later */
+#define sqlite3_value_subtype          sqlite3_api->value_subtype
+#define sqlite3_result_subtype         sqlite3_api->result_subtype
+#endif /* !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION) */
 
-#ifndef SQLITE_CORE
+#if !defined(SQLITE_CORE) && !defined(SQLITE_OMIT_LOAD_EXTENSION)
   /* This case when the file really is being compiled as a loadable 
   ** extension */
 # define SQLITE_EXTENSION_INIT1     const sqlite3_api_routines *sqlite3_api=0;
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 2adb78101..4a9b13531 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1385,18 +1385,20 @@ struct FuncDestructor {
 ** values must correspond to OPFLAG_LENGTHARG and OPFLAG_TYPEOFARG.  There
 ** are assert() statements in the code to verify this.
 */
-#define SQLITE_FUNC_ENCMASK  0x003 /* SQLITE_UTF8, SQLITE_UTF16BE or UTF16LE */
-#define SQLITE_FUNC_LIKE     0x004 /* Candidate for the LIKE optimization */
-#define SQLITE_FUNC_CASE     0x008 /* Case-sensitive LIKE-type function */
-#define SQLITE_FUNC_EPHEM    0x010 /* Ephemeral.  Delete with VDBE */
-#define SQLITE_FUNC_NEEDCOLL 0x020 /* sqlite3GetFuncCollSeq() might be called */
-#define SQLITE_FUNC_LENGTH   0x040 /* Built-in length() function */
-#define SQLITE_FUNC_TYPEOF   0x080 /* Built-in typeof() function */
-#define SQLITE_FUNC_COUNT    0x100 /* Built-in count(*) aggregate */
-#define SQLITE_FUNC_COALESCE 0x200 /* Built-in coalesce() or ifnull() */
-#define SQLITE_FUNC_UNLIKELY 0x400 /* Built-in unlikely() function */
-#define SQLITE_FUNC_CONSTANT 0x800 /* Constant inputs give a constant output */
-#define SQLITE_FUNC_MINMAX  0x1000 /* True for min() and max() aggregates */
+#define SQLITE_FUNC_ENCMASK  0x0003 /* SQLITE_UTF8, SQLITE_UTF16BE or UTF16LE */
+#define SQLITE_FUNC_LIKE     0x0004 /* Candidate for the LIKE optimization */
+#define SQLITE_FUNC_CASE     0x0008 /* Case-sensitive LIKE-type function */
+#define SQLITE_FUNC_EPHEM    0x0010 /* Ephemeral.  Delete with VDBE */
+#define SQLITE_FUNC_NEEDCOLL 0x0020 /* sqlite3GetFuncCollSeq() might be called*/
+#define SQLITE_FUNC_LENGTH   0x0040 /* Built-in length() function */
+#define SQLITE_FUNC_TYPEOF   0x0080 /* Built-in typeof() function */
+#define SQLITE_FUNC_COUNT    0x0100 /* Built-in count(*) aggregate */
+#define SQLITE_FUNC_COALESCE 0x0200 /* Built-in coalesce() or ifnull() */
+#define SQLITE_FUNC_UNLIKELY 0x0400 /* Built-in unlikely() function */
+#define SQLITE_FUNC_CONSTANT 0x0800 /* Constant inputs give a constant output */
+#define SQLITE_FUNC_MINMAX   0x1000 /* True for min() and max() aggregates */
+#define SQLITE_FUNC_SLOCHNG  0x2000 /* "Slow Change". Value constant during a
+                                    ** single query - might change over time */
 
 /*
 ** The following three macros, FUNCTION(), LIKEFUNC() and AGGREGATE() are
@@ -1412,6 +1414,12 @@ struct FuncDestructor {
 **   VFUNCTION(zName, nArg, iArg, bNC, xFunc)
 **     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag.
 **
+**   DFUNCTION(zName, nArg, iArg, bNC, xFunc)
+**     Like FUNCTION except it omits the SQLITE_FUNC_CONSTANT flag and
+**     adds the SQLITE_FUNC_SLOCHNG flag.  Used for date & time functions
+**     and functions like sqlite_version() that can change, but not during
+**     a single query.
+**
 **   AGGREGATE(zName, nArg, iArg, bNC, xStep, xFinal)
 **     Used to create an aggregate function definition implemented by
 **     the C functions xStep and xFinal. The first four parameters
@@ -1432,11 +1440,14 @@ struct FuncDestructor {
 #define VFUNCTION(zName, nArg, iArg, bNC, xFunc) \
   {nArg, SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
    SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
+#define DFUNCTION(zName, nArg, iArg, bNC, xFunc) \
+  {nArg, SQLITE_FUNC_SLOCHNG|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
+   SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
 #define FUNCTION2(zName, nArg, iArg, bNC, xFunc, extraFlags) \
   {nArg,SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL)|extraFlags,\
    SQLITE_INT_TO_PTR(iArg), 0, xFunc, 0, 0, #zName, 0, 0}
 #define STR_FUNCTION(zName, nArg, pArg, bNC, xFunc) \
-  {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
+  {nArg, SQLITE_FUNC_SLOCHNG|SQLITE_UTF8|(bNC*SQLITE_FUNC_NEEDCOLL), \
    pArg, 0, xFunc, 0, 0, #zName, 0, 0}
 #define LIKEFUNC(zName, nArg, arg, flags) \
   {nArg, SQLITE_FUNC_CONSTANT|SQLITE_UTF8|flags, \
@@ -1872,6 +1883,7 @@ struct Index {
   u8 *aSortOrder;          /* for each column: True==DESC, False==ASC */
   char **azColl;           /* Array of collation sequence names for index */
   Expr *pPartIdxWhere;     /* WHERE clause for partial indices */
+  ExprList *aColExpr;      /* Column expressions */
   int tnum;                /* DB Page containing root of this index */
   LogEst szIdxRow;         /* Estimated average row size in bytes */
   u16 nKeyCol;             /* Number of columns forming the key */
@@ -2121,9 +2133,10 @@ struct Expr {
 #define EP_MemToken  0x010000 /* Need to sqlite3DbFree() Expr.zToken */
 #define EP_NoReduce  0x020000 /* Cannot EXPRDUP_REDUCE this Expr */
 #define EP_Unlikely  0x040000 /* unlikely() or likelihood() function */
-#define EP_ConstFunc 0x080000 /* Node is a SQLITE_FUNC_CONSTANT function */
+#define EP_ConstFunc 0x080000 /* A SQLITE_FUNC_CONSTANT or _SLOCHNG function */
 #define EP_CanBeNull 0x100000 /* Can be null despite NOT NULL constraint */
 #define EP_Subquery  0x200000 /* Tree contains a TK_SELECT operator */
+#define EP_Alias     0x400000 /* Is an alias for a result set column */
 
 /*
 ** Combinations of two or more EP_* flags
@@ -2340,6 +2353,7 @@ struct SrcList {
 #define WHERE_WANT_DISTINCT    0x0400 /* All output needs to be distinct */
 #define WHERE_SORTBYGROUP      0x0800 /* Support sqlite3WhereIsSorted() */
 #define WHERE_REOPEN_IDX       0x1000 /* Try to use OP_ReopenIdx */
+#define WHERE_ONEPASS_MULTIROW 0x2000 /* ONEPASS is ok with multiple rows */
 
 /* Allowed return values from sqlite3WhereIsDistinct()
 */
@@ -2392,6 +2406,7 @@ struct NameContext {
 #define NC_IsCheck   0x0004  /* True if resolving names in a CHECK constraint */
 #define NC_InAggFunc 0x0008  /* True if analyzing arguments to an agg func */
 #define NC_PartIdx   0x0010  /* True if resolving a partial index WHERE */
+#define NC_IdxExpr   0x0020  /* True if resolving columns of CREATE INDEX */
 #define NC_MinMaxAgg 0x1000  /* min/max aggregates seen.  See note above */
 
 /*
@@ -2661,7 +2676,7 @@ struct Parse {
   int nOpAlloc;        /* Number of slots allocated for Vdbe.aOp[] */
   int iFixedOp;        /* Never back out opcodes iFixedOp-1 or earlier */
   int ckBase;          /* Base register of data during check constraints */
-  int iPartIdxTab;     /* Table corresponding to a partial index */
+  int iSelfTab;        /* Table of an index whose exprs are being coded */
   int iCacheLevel;     /* ColCache valid when aColCache[].iLevel<=iCacheLevel */
   int iCacheCnt;       /* Counter used to generate aColCache[].lru values */
   int nLabel;          /* Number of labels used */
@@ -3181,6 +3196,11 @@ const sqlite3_mem_methods *sqlite3MemGetMemsys5(void);
   int sqlite3MutexInit(void);
   int sqlite3MutexEnd(void);
 #endif
+#if !defined(SQLITE_MUTEX_OMIT) && !defined(SQLITE_MUTEX_NOOP)
+  void sqlite3MemoryBarrier(void);
+#else
+# define sqlite3MemoryBarrier()
+#endif
 
 sqlite3_int64 sqlite3StatusValue(int);
 void sqlite3StatusUp(int, int);
@@ -3364,6 +3384,10 @@ int sqlite3WhereIsSorted(WhereInfo*);
 int sqlite3WhereContinueLabel(WhereInfo*);
 int sqlite3WhereBreakLabel(WhereInfo*);
 int sqlite3WhereOkOnePass(WhereInfo*, int*);
+#define ONEPASS_OFF      0        /* Use of ONEPASS not allowed */
+#define ONEPASS_SINGLE   1        /* ONEPASS valid for a single row update */
+#define ONEPASS_MULTI    2        /* ONEPASS is valid for multiple rows */
+void sqlite3ExprCodeLoadIndexColumn(Parse*, Index*, int, int, int);
 int sqlite3ExprCodeGetColumn(Parse*, Table*, int, int, int, u8);
 void sqlite3ExprCodeGetColumnOfTable(Vdbe*, Table*, int, int, int);
 void sqlite3ExprCodeMove(Parse*, int, int, int);
@@ -3426,8 +3450,9 @@ int sqlite3ExprIsInteger(Expr*, int*);
 int sqlite3ExprCanBeNull(const Expr*);
 int sqlite3ExprNeedsNoAffinityChange(const Expr*, char);
 int sqlite3IsRowid(const char*);
-void sqlite3GenerateRowDelete(Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8);
-void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*);
+void sqlite3GenerateRowDelete(
+    Parse*,Table*,Trigger*,int,int,int,i16,u8,u8,u8,int);
+void sqlite3GenerateRowIndexDelete(Parse*, Table*, int, int, int*, int);
 int sqlite3GenerateIndexKey(Parse*, Index*, int, int, int, int*,Index*,int);
 void sqlite3ResolvePartIdxLabel(Parse*,int);
 void sqlite3GenerateConstraintChecks(Parse*,Table*,int*,int,int,int,int,
diff --git a/src/test_func.c b/src/test_func.c
index 2e34fa074..63cf18e3f 100644
--- a/src/test_func.c
+++ b/src/test_func.c
@@ -462,7 +462,7 @@ static void real2hex(
 }
 
 /*
-** tclcmd: test_extract(record, field)
+**     test_extract(record, field)
 **
 ** This function implements an SQL user-function that accepts a blob
 ** containing a formatted database record as the first argument. The
@@ -509,7 +509,7 @@ static void test_extract(
 }
 
 /*
-** tclcmd: test_decode(record)
+**      test_decode(record)
 **
 ** This function implements an SQL user-function that accepts a blob
 ** containing a formatted database record as its only argument. It returns
@@ -601,6 +601,8 @@ static void test_decode(
 }
 
 /*
+**       test_zeroblob(N)
+**
 ** The implementation of scalar SQL function "test_zeroblob()". This is
 ** similar to the built-in zeroblob() function, except that it does not
 ** check that the integer parameter is within range before passing it
@@ -615,6 +617,31 @@ static void test_zeroblob(
   sqlite3_result_zeroblob(context, nZero);
 }
 
+/*         test_getsubtype(V)
+**
+** Return the subtype for value V.
+*/
+static void test_getsubtype(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  sqlite3_result_int(context, (int)sqlite3_value_subtype(argv[0]));
+}
+
+/*         test_setsubtype(V, T)
+**
+** Return the value V with its subtype changed to T
+*/
+static void test_setsubtype(
+  sqlite3_context *context,
+  int argc,
+  sqlite3_value **argv
+){
+  sqlite3_result_value(context, argv[0]);
+  sqlite3_result_subtype(context, (unsigned int)sqlite3_value_int(argv[1]));
+}
+
 static int registerTestFunctions(sqlite3 *db){
   static const struct {
      char *zName;
@@ -641,6 +668,8 @@ static int registerTestFunctions(sqlite3 *db){
     { "test_decode",           1, SQLITE_UTF8, test_decode},
     { "test_extract",          2, SQLITE_UTF8, test_extract},
     { "test_zeroblob",  1, SQLITE_UTF8|SQLITE_DETERMINISTIC, test_zeroblob},
+    { "test_getsubtype",       1, SQLITE_UTF8, test_getsubtype},
+    { "test_setsubtype",       2, SQLITE_UTF8, test_setsubtype},
   };
   int i;
 
diff --git a/src/tokenize.c b/src/tokenize.c
index 3d08f75a2..6b5ad2790 100644
--- a/src/tokenize.c
+++ b/src/tokenize.c
@@ -403,6 +403,7 @@ int sqlite3RunParser(Parse *pParse, const char *zSql, char **pzErrMsg){
   pParse->zTail = zSql;
   i = 0;
   assert( pzErrMsg!=0 );
+  /* sqlite3ParserTrace(stdout, "parser: "); */
   pEngine = sqlite3ParserAlloc(sqlite3Malloc);
   if( pEngine==0 ){
     db->mallocFailed = 1;
diff --git a/src/treeview.c b/src/treeview.c
index 59c07e474..971de4e8b 100644
--- a/src/treeview.c
+++ b/src/treeview.c
@@ -253,11 +253,6 @@ void sqlite3TreeViewExpr(TreeView *pView, const Expr *pExpr, u8 moreToFollow){
       sqlite3TreeViewLine(pView,"REGISTER(%d)", pExpr->iTable);
       break;
     }
-    case TK_AS: {
-      sqlite3TreeViewLine(pView,"AS %Q", pExpr->u.zToken);
-      sqlite3TreeViewExpr(pView, pExpr->pLeft, 0);
-      break;
-    }
     case TK_ID: {
       sqlite3TreeViewLine(pView,"ID \"%w\"", pExpr->u.zToken);
       break;
diff --git a/src/update.c b/src/update.c
index f7b4dcd93..94f7a4dd9 100644
--- a/src/update.c
+++ b/src/update.c
@@ -272,7 +272,9 @@ void sqlite3Update(
 
   /* There is one entry in the aRegIdx[] array for each index on the table
   ** being updated.  Fill in aRegIdx[] with a register number that will hold
-  ** the key for accessing each index.  
+  ** the key for accessing each index.
+  **
+  ** FIXME:  Be smarter about omitting indexes that use expressions.
   */
   for(j=0, pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext, j++){
     int reg;
@@ -281,7 +283,8 @@ void sqlite3Update(
     }else{
       reg = 0;
       for(i=0; i<pIdx->nKeyCol; i++){
-        if( aXRef[pIdx->aiColumn[i]]>=0 ){
+        i16 iIdxCol = pIdx->aiColumn[i];
+        if( iIdxCol<0 || aXRef[iIdxCol]>=0 ){
           reg = ++pParse->nMem;
           break;
         }
@@ -381,6 +384,7 @@ void sqlite3Update(
     if( pWInfo==0 ) goto update_cleanup;
     okOnePass = sqlite3WhereOkOnePass(pWInfo, aiCurOnePass);
     for(i=0; i<nPk; i++){
+      assert( pPk->aiColumn[i]>=(-1) );
       sqlite3ExprCodeGetColumnOfTable(v, pTab, iDataCur, pPk->aiColumn[i],
                                       iPk+i);
     }
@@ -583,7 +587,7 @@ void sqlite3Update(
       }
       VdbeCoverageNeverTaken(v);
     }
-    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, aRegIdx);
+    sqlite3GenerateRowIndexDelete(pParse, pTab, iDataCur, iIdxCur, aRegIdx, -1);
   
     /* If changing the record number, delete the old record.  */
     if( hasFK || chngKey || pPk!=0 ){
diff --git a/src/vdbe.c b/src/vdbe.c
index caf3acabb..41ad915b1 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3972,9 +3972,10 @@ case OP_Found: {        /* jump, in3 */
 **
 ** P1 is the index of a cursor open on an SQL table btree (with integer
 ** keys).  P3 is an integer rowid.  If P1 does not contain a record with
-** rowid P3 then jump immediately to P2.  If P1 does contain a record
-** with rowid P3 then leave the cursor pointing at that record and fall
-** through to the next instruction.
+** rowid P3 then jump immediately to P2.  Or, if P2 is 0, raise an
+** SQLITE_CORRUPT error. If P1 does contain a record with rowid P3 then 
+** leave the cursor pointing at that record and fall through to the next
+** instruction.
 **
 ** The OP_NotFound opcode performs the same operation on index btrees
 ** (with arbitrary multi-value keys).
@@ -4006,13 +4007,21 @@ case OP_NotExists: {        /* jump, in3 */
   res = 0;
   iKey = pIn3->u.i;
   rc = sqlite3BtreeMovetoUnpacked(pCrsr, 0, iKey, 0, &res);
+  assert( rc==SQLITE_OK || res==0 );
   pC->movetoTarget = iKey;  /* Used by OP_Delete */
   pC->nullRow = 0;
   pC->cacheStatus = CACHE_STALE;
   pC->deferredMoveto = 0;
   VdbeBranchTaken(res!=0,2);
   pC->seekResult = res;
-  if( res!=0 ) goto jump_to_p2;
+  if( res!=0 ){
+    assert( rc==SQLITE_OK );
+    if( pOp->p2==0 ){
+      rc = SQLITE_CORRUPT_BKPT;
+    }else{
+      goto jump_to_p2;
+    }
+  }
   break;
 }
 
@@ -4278,14 +4287,15 @@ case OP_InsertInt: {
   break;
 }
 
-/* Opcode: Delete P1 P2 * P4 *
+/* Opcode: Delete P1 P2 * P4 P5
 **
 ** Delete the record at which the P1 cursor is currently pointing.
 **
-** The cursor will be left pointing at either the next or the previous
-** record in the table. If it is left pointing at the next record, then
-** the next Next instruction will be a no-op.  Hence it is OK to delete
-** a record from within a Next loop.
+** If the P5 parameter is non-zero, the cursor will be left pointing at 
+** either the next or the previous record in the table. If it is left 
+** pointing at the next record, then the next Next instruction will be a 
+** no-op. As a result, in this case it is OK to delete a record from within a
+** Next loop. If P5 is zero, then the cursor is left in an undefined state.
 **
 ** If the OPFLAG_NCHANGE flag of P2 is set, then the row change count is
 ** incremented (otherwise not).
@@ -4300,6 +4310,7 @@ case OP_InsertInt: {
 */
 case OP_Delete: {
   VdbeCursor *pC;
+  u8 hasUpdateCallback;
 
   assert( pOp->p1>=0 && pOp->p1<p->nCursor );
   pC = p->apCsr[pOp->p1];
@@ -4307,22 +4318,27 @@ case OP_Delete: {
   assert( pC->pCursor!=0 );  /* Only valid for real tables, no pseudotables */
   assert( pC->deferredMoveto==0 );
 
+  hasUpdateCallback = db->xUpdateCallback && pOp->p4.z && pC->isTable;
+  if( pOp->p5 && hasUpdateCallback ){
+    sqlite3BtreeKeySize(pC->pCursor, &pC->movetoTarget);
+  }
+
 #ifdef SQLITE_DEBUG
   /* The seek operation that positioned the cursor prior to OP_Delete will
   ** have also set the pC->movetoTarget field to the rowid of the row that
   ** is being deleted */
-  if( pOp->p4.z && pC->isTable ){
+  if( pOp->p4.z && pC->isTable && pOp->p5==0 ){
     i64 iKey = 0;
     sqlite3BtreeKeySize(pC->pCursor, &iKey);
     assert( pC->movetoTarget==iKey ); 
   }
 #endif
  
-  rc = sqlite3BtreeDelete(pC->pCursor);
+  rc = sqlite3BtreeDelete(pC->pCursor, pOp->p5);
   pC->cacheStatus = CACHE_STALE;
 
   /* Invoke the update-hook if required. */
-  if( rc==SQLITE_OK && db->xUpdateCallback && pOp->p4.z && pC->isTable ){
+  if( rc==SQLITE_OK && hasUpdateCallback ){
     db->xUpdateCallback(db->pUpdateArg, SQLITE_DELETE,
                         db->aDb[pC->iDb].zName, pOp->p4.z, pC->movetoTarget);
     assert( pC->iDb>=0 );
@@ -4861,7 +4877,7 @@ case OP_IdxDelete: {
 #endif
   rc = sqlite3BtreeMovetoUnpacked(pCrsr, &r, 0, 0, &res);
   if( rc==SQLITE_OK && res==0 ){
-    rc = sqlite3BtreeDelete(pCrsr);
+    rc = sqlite3BtreeDelete(pCrsr, 0);
   }
   assert( pC->deferredMoveto==0 );
   pC->cacheStatus = CACHE_STALE;
diff --git a/src/vdbeInt.h b/src/vdbeInt.h
index b5470c2dd..45892a899 100644
--- a/src/vdbeInt.h
+++ b/src/vdbeInt.h
@@ -186,6 +186,7 @@ struct Mem {
   } u;
   u16 flags;          /* Some combination of MEM_Null, MEM_Str, MEM_Dyn, etc. */
   u8  enc;            /* SQLITE_UTF8, SQLITE_UTF16BE, SQLITE_UTF16LE */
+  u8  eSubtype;       /* Subtype for this value */
   int n;              /* Number of characters in string value, excluding '\0' */
   char *z;            /* String or BLOB value */
   /* ShallowCopy only needs to copy the information above */
diff --git a/src/vdbeapi.c b/src/vdbeapi.c
index 15a8bba0d..06b14e127 100644
--- a/src/vdbeapi.c
+++ b/src/vdbeapi.c
@@ -187,6 +187,9 @@ int sqlite3_value_int(sqlite3_value *pVal){
 sqlite_int64 sqlite3_value_int64(sqlite3_value *pVal){
   return sqlite3VdbeIntValue((Mem*)pVal);
 }
+unsigned int sqlite3_value_subtype(sqlite3_value *pVal){
+  return ((Mem*)pVal)->eSubtype;
+}
 const unsigned char *sqlite3_value_text(sqlite3_value *pVal){
   return (const unsigned char *)sqlite3ValueText(pVal, SQLITE_UTF8);
 }
@@ -365,6 +368,10 @@ void sqlite3_result_null(sqlite3_context *pCtx){
   assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
   sqlite3VdbeMemSetNull(pCtx->pOut);
 }
+void sqlite3_result_subtype(sqlite3_context *pCtx, unsigned int eSubtype){
+  assert( sqlite3_mutex_held(pCtx->pOut->db->mutex) );
+  pCtx->pOut->eSubtype = eSubtype & 0xff;
+}
 void sqlite3_result_text(
   sqlite3_context *pCtx, 
   const char *z, 
@@ -696,7 +703,7 @@ void *sqlite3_user_data(sqlite3_context *p){
 ** application defined function.
 */
 sqlite3 *sqlite3_context_db_handle(sqlite3_context *p){
-  assert( p && p->pFunc );
+  assert( p && p->pOut );
   return p->pOut->db;
 }
 
diff --git a/src/vdbeblob.c b/src/vdbeblob.c
index ea01f5ce8..2cdc3edb0 100644
--- a/src/vdbeblob.c
+++ b/src/vdbeblob.c
@@ -247,7 +247,8 @@ int sqlite3_blob_open(
       for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
         int j;
         for(j=0; j<pIdx->nKeyCol; j++){
-          if( pIdx->aiColumn[j]==iCol ){
+          /* FIXME: Be smarter about indexes that use expressions */
+          if( pIdx->aiColumn[j]==iCol || pIdx->aiColumn[j]==(-2) ){
             zFault = "indexed";
           }
         }
diff --git a/src/vdbemem.c b/src/vdbemem.c
index 648a53d2a..28dd5d957 100644
--- a/src/vdbemem.c
+++ b/src/vdbemem.c
@@ -1155,7 +1155,7 @@ static sqlite3_value *valueNew(sqlite3 *db, struct ValueNewStat4Ctx *p){
 ** to be a scalar SQL function. If
 **
 **   * all function arguments are SQL literals,
-**   * the SQLITE_FUNC_CONSTANT function flag is set, and
+**   * one of the SQLITE_FUNC_CONSTANT or _SLOCHNG function flags is set, and
 **   * the SQLITE_FUNC_NEEDCOLL function flag is not set,
 **
 ** then this routine attempts to invoke the SQL function. Assuming no
@@ -1196,7 +1196,7 @@ static int valueFromFunction(
   nName = sqlite3Strlen30(p->u.zToken);
   pFunc = sqlite3FindFunction(db, p->u.zToken, nName, nVal, enc, 0);
   assert( pFunc );
-  if( (pFunc->funcFlags & SQLITE_FUNC_CONSTANT)==0 
+  if( (pFunc->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG))==0 
    || (pFunc->funcFlags & SQLITE_FUNC_NEEDCOLL)
   ){
     return SQLITE_OK;
diff --git a/src/wal.c b/src/wal.c
index cf8f1d4e6..d87d2c17c 100644
--- a/src/wal.c
+++ b/src/wal.c
@@ -2462,7 +2462,8 @@ int sqlite3WalFindFrame(
   {
     u32 iRead2 = 0;
     u32 iTest;
-    for(iTest=iLast; iTest>0; iTest--){
+    assert( pWal->minFrame>0 );
+    for(iTest=iLast; iTest>=pWal->minFrame; iTest--){
       if( walFramePgno(pWal, iTest)==pgno ){
         iRead2 = iTest;
         break;
diff --git a/src/where.c b/src/where.c
index de8a041e7..fc849ccdb 100644
--- a/src/where.c
+++ b/src/where.c
@@ -69,9 +69,11 @@ int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
 }
 
 /*
-** Return TRUE if an UPDATE or DELETE statement can operate directly on
-** the rowids returned by a WHERE clause.  Return FALSE if doing an
-** UPDATE or DELETE might change subsequent WHERE clause results.
+** Return ONEPASS_OFF (0) if an UPDATE or DELETE statement is unable to
+** operate directly on the rowis returned by a WHERE clause.  Return
+** ONEPASS_SINGLE (1) if the statement can operation directly because only
+** a single row is to be changed.  Return ONEPASS_MULTI (2) if the one-pass
+** optimization can be used on multiple 
 **
 ** If the ONEPASS optimization is used (if this routine returns true)
 ** then also write the indices of open cursors used by ONEPASS
@@ -85,7 +87,7 @@ int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
 */
 int sqlite3WhereOkOnePass(WhereInfo *pWInfo, int *aiCur){
   memcpy(aiCur, pWInfo->aiCurOnePass, sizeof(int)*2);
-  return pWInfo->okOnePass;
+  return pWInfo->eOnePass;
 }
 
 /*
@@ -180,10 +182,13 @@ static WhereTerm *whereScanNext(WhereScan *pScan){
   while( pScan->iEquiv<=pScan->nEquiv ){
     iCur = pScan->aiCur[pScan->iEquiv-1];
     iColumn = pScan->aiColumn[pScan->iEquiv-1];
+    assert( iColumn!=(-2) || pScan->pIdxExpr!=0 );
     while( (pWC = pScan->pWC)!=0 ){
       for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
         if( pTerm->leftCursor==iCur
          && pTerm->u.leftColumn==iColumn
+         && (iColumn!=(-2)
+               || sqlite3ExprCompare(pTerm->pExpr->pLeft,pScan->pIdxExpr,iCur)==0)
          && (pScan->iEquiv<=1 || !ExprHasProperty(pTerm->pExpr, EP_FromJoin))
         ){
           if( (pTerm->eOperator & WO_EQUIV)!=0
@@ -268,16 +273,19 @@ static WhereTerm *whereScanInit(
   u32 opMask,             /* Operator(s) to scan for */
   Index *pIdx             /* Must be compatible with this index */
 ){
-  int j;
+  int j = 0;
 
   /* memset(pScan, 0, sizeof(*pScan)); */
   pScan->pOrigWC = pWC;
   pScan->pWC = pWC;
+  pScan->pIdxExpr = 0;
+  if( pIdx ){
+    j = iColumn;
+    iColumn = pIdx->aiColumn[j];
+    if( iColumn==(-2) ) pScan->pIdxExpr = pIdx->aColExpr->a[j].pExpr;
+  }
   if( pIdx && iColumn>=0 ){
     pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
-    for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
-      if( NEVER(j>pIdx->nColumn) ) return 0;
-    }
     pScan->zCollName = pIdx->azColl[j];
   }else{
     pScan->idxaff = 0;
@@ -298,6 +306,9 @@ static WhereTerm *whereScanInit(
 ** the WO_xx operator codes specified by the op parameter.
 ** Return a pointer to the term.  Return 0 if not found.
 **
+** If pIdx!=0 then search for terms matching the iColumn-th column of pIdx
+** rather than the iColumn-th column of table iCur.
+**
 ** The term returned might by Y=<expr> if there is another constraint in
 ** the WHERE clause that specifies that X=Y.  Any such constraints will be
 ** identified by the WO_EQUIV bit in the pTerm->eOperator field.  The
@@ -374,6 +385,25 @@ static int findIndexCol(
 }
 
 /*
+** Return TRUE if the iCol-th column of index pIdx is NOT NULL
+*/
+static int indexColumnNotNull(Index *pIdx, int iCol){
+  int j;
+  assert( pIdx!=0 );
+  assert( iCol>=0 && iCol<pIdx->nColumn );
+  j = pIdx->aiColumn[iCol];
+  if( j>=0 ){
+    return pIdx->pTable->aCol[j].notNull;
+  }else if( j==(-1) ){
+    return 1;
+  }else{
+    assert( j==(-2) );
+    return 0;  /* Assume an indexed expression can always yield a NULL */
+
+  }
+}
+
+/*
 ** Return true if the DISTINCT expression-list passed as the third argument
 ** is redundant.
 **
@@ -423,12 +453,9 @@ static int isDistinctRedundant(
   for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
     if( !IsUniqueIndex(pIdx) ) continue;
     for(i=0; i<pIdx->nKeyCol; i++){
-      i16 iCol = pIdx->aiColumn[i];
-      if( 0==sqlite3WhereFindTerm(pWC, iBase, iCol, ~(Bitmask)0, WO_EQ, pIdx) ){
-        int iIdxCol = findIndexCol(pParse, pDistinct, iBase, pIdx, i);
-        if( iIdxCol<0 || pTab->aCol[iCol].notNull==0 ){
-          break;
-        }
+      if( 0==sqlite3WhereFindTerm(pWC, iBase, i, ~(Bitmask)0, WO_EQ, pIdx) ){
+        if( findIndexCol(pParse, pDistinct, iBase, pIdx, i)<0 ) break;
+        if( indexColumnNotNull(pIdx, i)==0 ) break;
       }
     }
     if( i==pIdx->nKeyCol ){
@@ -780,6 +807,7 @@ static sqlite3_index_info *allocateIndexInfo(
     testcase( pTerm->eOperator & WO_ALL );
     if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
     if( pTerm->wtFlags & TERM_VNULL ) continue;
+    assert( pTerm->u.leftColumn>=(-1) );
     nTerm++;
   }
 
@@ -835,6 +863,7 @@ static sqlite3_index_info *allocateIndexInfo(
     testcase( pTerm->eOperator & WO_ALL );
     if( (pTerm->eOperator & ~(WO_ISNULL|WO_EQUIV|WO_IS))==0 ) continue;
     if( pTerm->wtFlags & TERM_VNULL ) continue;
+    assert( pTerm->u.leftColumn>=(-1) );
     pIdxCons[j].iColumn = pTerm->u.leftColumn;
     pIdxCons[j].iTermOffset = i;
     op = (u8)pTerm->eOperator & WO_ALL;
@@ -2126,7 +2155,6 @@ static int whereLoopAddBtreeIndex(
   u16 saved_nSkip;                /* Original value of pNew->nSkip */
   u32 saved_wsFlags;              /* Original value of pNew->wsFlags */
   LogEst saved_nOut;              /* Original value of pNew->nOut */
-  int iCol;                       /* Index of the column in the table */
   int rc = SQLITE_OK;             /* Return code */
   LogEst rSize;                   /* Number of rows in the table */
   LogEst rLogSize;                /* Logarithm of table size */
@@ -2147,16 +2175,15 @@ static int whereLoopAddBtreeIndex(
   if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE);
 
   assert( pNew->u.btree.nEq<pProbe->nColumn );
-  iCol = pProbe->aiColumn[pNew->u.btree.nEq];
 
-  pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, iCol,
-                        opMask, pProbe);
   saved_nEq = pNew->u.btree.nEq;
   saved_nSkip = pNew->nSkip;
   saved_nLTerm = pNew->nLTerm;
   saved_wsFlags = pNew->wsFlags;
   saved_prereq = pNew->prereq;
   saved_nOut = pNew->nOut;
+  pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, saved_nEq,
+                        opMask, pProbe);
   pNew->rSetup = 0;
   rSize = pProbe->aiRowLogEst[0];
   rLogSize = estLog(rSize);
@@ -2169,7 +2196,7 @@ static int whereLoopAddBtreeIndex(
     int nRecValid = pBuilder->nRecValid;
 #endif
     if( (eOp==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0)
-     && (iCol<0 || pSrc->pTab->aCol[iCol].notNull)
+     && indexColumnNotNull(pProbe, saved_nEq)
     ){
       continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */
     }
@@ -2206,8 +2233,10 @@ static int whereLoopAddBtreeIndex(
                         ** changes "x IN (?)" into "x=?". */
 
     }else if( eOp & (WO_EQ|WO_IS) ){
+      int iCol = pProbe->aiColumn[saved_nEq];
       pNew->wsFlags |= WHERE_COLUMN_EQ;
-      if( iCol<0 || (nInMul==0 && pNew->u.btree.nEq==pProbe->nKeyCol-1) ){
+      assert( saved_nEq==pNew->u.btree.nEq );
+      if( iCol==(-1) || (iCol>0 && nInMul==0 && saved_nEq==pProbe->nKeyCol-1) ){
         if( iCol>=0 && pProbe->uniqNotNull==0 ){
           pNew->wsFlags |= WHERE_UNQ_WANTED;
         }else{
@@ -2258,7 +2287,7 @@ static int whereLoopAddBtreeIndex(
       assert( eOp & (WO_ISNULL|WO_EQ|WO_IN|WO_IS) );
 
       assert( pNew->nOut==saved_nOut );
-      if( pTerm->truthProb<=0 && iCol>=0 ){
+      if( pTerm->truthProb<=0 && pProbe->aiColumn[saved_nEq]>=0 ){
         assert( (eOp & WO_IN) || nIn==0 );
         testcase( eOp & WO_IN );
         pNew->nOut += pTerm->truthProb;
@@ -3785,7 +3814,7 @@ static int whereShortCut(WhereLoopBuilder *pBuilder){
       ) continue;
       opMask = pIdx->uniqNotNull ? (WO_EQ|WO_IS) : WO_EQ;
       for(j=0; j<pIdx->nKeyCol; j++){
-        pTerm = sqlite3WhereFindTerm(pWC, iCur, pIdx->aiColumn[j], 0, opMask, pIdx);
+        pTerm = sqlite3WhereFindTerm(pWC, iCur, j, 0, opMask, pIdx);
         if( pTerm==0 ) break;
         testcase( pTerm->eOperator & WO_IS );
         pLoop->aLTerm[j] = pTerm;
@@ -3931,6 +3960,10 @@ WhereInfo *sqlite3WhereBegin(
   sqlite3 *db;               /* Database connection */
   int rc;                    /* Return code */
 
+  assert( (wctrlFlags & WHERE_ONEPASS_MULTIROW)==0 || (
+        (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
+     && (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 
+  ));
 
   /* Variable initialization */
   db = pParse->db;
@@ -3986,6 +4019,7 @@ WhereInfo *sqlite3WhereBegin(
   pWInfo->iBreak = pWInfo->iContinue = sqlite3VdbeMakeLabel(v);
   pWInfo->wctrlFlags = wctrlFlags;
   pWInfo->savedNQueryLoop = pParse->nQueryLoop;
+  assert( pWInfo->eOnePass==ONEPASS_OFF );  /* ONEPASS defaults to OFF */
   pMaskSet = &pWInfo->sMaskSet;
   sWLB.pWInfo = pWInfo;
   sWLB.pWC = &pWInfo->sWC;
@@ -4025,14 +4059,12 @@ WhereInfo *sqlite3WhereBegin(
 
   /* Assign a bit from the bitmask to every term in the FROM clause.
   **
-  ** When assigning bitmask values to FROM clause cursors, it must be
-  ** the case that if X is the bitmask for the N-th FROM clause term then
-  ** the bitmask for all FROM clause terms to the left of the N-th term
-  ** is (X-1).   An expression from the ON clause of a LEFT JOIN can use
-  ** its Expr.iRightJoinTable value to find the bitmask of the right table
-  ** of the join.  Subtracting one from the right table bitmask gives a
-  ** bitmask for all tables to the left of the join.  Knowing the bitmask
-  ** for all tables to the left of a left join is important.  Ticket #3015.
+  ** The N-th term of the FROM clause is assigned a bitmask of 1<<N.
+  **
+  ** The rule of the previous sentence ensures thta if X is the bitmask for
+  ** a table T, then X-1 is the bitmask for all other tables to the left of T.
+  ** Knowing the bitmask for all tables to the left of a left join is
+  ** important.  Ticket #3015.
   **
   ** Note that bitmasks are created for all pTabList->nSrc tables in
   ** pTabList, not just the first nTabList tables.  nTabList is normally
@@ -4043,14 +4075,10 @@ WhereInfo *sqlite3WhereBegin(
     createMask(pMaskSet, pTabList->a[ii].iCursor);
     sqlite3WhereTabFuncArgs(pParse, &pTabList->a[ii], &pWInfo->sWC);
   }
-#ifndef NDEBUG
-  {
-    Bitmask toTheLeft = 0;
-    for(ii=0; ii<pTabList->nSrc; ii++){
-      Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor);
-      assert( (m-1)==toTheLeft );
-      toTheLeft |= m;
-    }
+#ifdef SQLITE_DEBUG
+  for(ii=0; ii<pTabList->nSrc; ii++){
+    Bitmask m = sqlite3WhereGetMask(pMaskSet, pTabList->a[ii].iCursor);
+    assert( m==MASKBIT(ii) );
   }
 #endif
 
@@ -4178,11 +4206,16 @@ WhereInfo *sqlite3WhereBegin(
   ** the statement to update or delete a single row.
   */
   assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
-  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
-   && (pWInfo->a[0].pWLoop->wsFlags & WHERE_ONEROW)!=0 ){
-    pWInfo->okOnePass = 1;
-    if( HasRowid(pTabList->a[0].pTab) ){
-      pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
+  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 ){
+    int wsFlags = pWInfo->a[0].pWLoop->wsFlags;
+    int bOnerow = (wsFlags & WHERE_ONEROW)!=0;
+    if( bOnerow || ( (wctrlFlags & WHERE_ONEPASS_MULTIROW)
+       && 0==(wsFlags & WHERE_VIRTUALTABLE)
+    )){
+      pWInfo->eOnePass = bOnerow ? ONEPASS_SINGLE : ONEPASS_MULTI;
+      if( HasRowid(pTabList->a[0].pTab) ){
+        pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
+      }
     }
   }
 
@@ -4213,15 +4246,15 @@ WhereInfo *sqlite3WhereBegin(
     if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
          && (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 ){
       int op = OP_OpenRead;
-      if( pWInfo->okOnePass ){
+      if( pWInfo->eOnePass!=ONEPASS_OFF ){
         op = OP_OpenWrite;
         pWInfo->aiCurOnePass[0] = pTabItem->iCursor;
       };
       sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
       assert( pTabItem->iCursor==pLevel->iTabCur );
-      testcase( !pWInfo->okOnePass && pTab->nCol==BMS-1 );
-      testcase( !pWInfo->okOnePass && pTab->nCol==BMS );
-      if( !pWInfo->okOnePass && pTab->nCol<BMS && HasRowid(pTab) ){
+      testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS-1 );
+      testcase( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol==BMS );
+      if( pWInfo->eOnePass==ONEPASS_OFF && pTab->nCol<BMS && HasRowid(pTab) ){
         Bitmask b = pTabItem->colUsed;
         int n = 0;
         for(; b; b=b>>1, n++){}
@@ -4252,7 +4285,7 @@ WhereInfo *sqlite3WhereBegin(
         ** WITHOUT ROWID table.  No need for a separate index */
         iIndexCur = pLevel->iTabCur;
         op = 0;
-      }else if( pWInfo->okOnePass ){
+      }else if( pWInfo->eOnePass!=ONEPASS_OFF ){
         Index *pJ = pTabItem->pTab->pIndex;
         iIndexCur = iIdxCur;
         assert( wctrlFlags & WHERE_ONEPASS_DESIRED );
@@ -4460,7 +4493,7 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
      && (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
     ){
       int ws = pLoop->wsFlags;
-      if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
+      if( pWInfo->eOnePass==ONEPASS_OFF && (ws & WHERE_IDX_ONLY)==0 ){
         sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
       }
       if( (ws & WHERE_INDEXED)!=0
diff --git a/src/whereInt.h b/src/whereInt.h
index 7138b85b2..cae09acc8 100644
--- a/src/whereInt.h
+++ b/src/whereInt.h
@@ -286,6 +286,7 @@ struct WhereScan {
   WhereClause *pOrigWC;      /* Original, innermost WhereClause */
   WhereClause *pWC;          /* WhereClause currently being scanned */
   char *zCollName;           /* Required collating sequence, if not NULL */
+  Expr *pIdxExpr;            /* Search for this index expression */
   char idxaff;               /* Must match this affinity, if zCollName!=NULL */
   unsigned char nEquiv;      /* Number of entries in aEquiv[] */
   unsigned char iEquiv;      /* Next unused slot in aEquiv[] */
@@ -411,7 +412,7 @@ struct WhereInfo {
   u16 wctrlFlags;           /* Flags originally passed to sqlite3WhereBegin() */
   i8 nOBSat;                /* Number of ORDER BY terms satisfied by indices */
   u8 sorted;                /* True if really sorted (not just grouped) */
-  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
+  u8 eOnePass;              /* ONEPASS_OFF, or _SINGLE, or _MULTI */
   u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
   u8 eDistinct;             /* One of the WHERE_DISTINCT_* values below */
   u8 nLevel;                /* Number of nested loop */
diff --git a/src/wherecode.c b/src/wherecode.c
index e5e0c0a6e..ec24ba0ac 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -42,6 +42,16 @@ static void explainAppendTerm(
 }
 
 /*
+** Return the name of the i-th column of the pIdx index.
+*/
+static const char *explainIndexColumnName(Index *pIdx, int i){
+  i = pIdx->aiColumn[i];
+  if( i==(-2) ) return "<expr>";
+  if( i==(-1) ) return "rowid";
+  return pIdx->pTable->aCol[i].zName;
+}
+
+/*
 ** Argument pLevel describes a strategy for scanning table pTab. This 
 ** function appends text to pStr that describes the subset of table
 ** rows scanned by the strategy in the form of an SQL expression.
@@ -60,24 +70,22 @@ static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop, Table *pTab){
   u16 nEq = pLoop->u.btree.nEq;
   u16 nSkip = pLoop->nSkip;
   int i, j;
-  Column *aCol = pTab->aCol;
-  i16 *aiColumn = pIndex->aiColumn;
 
   if( nEq==0 && (pLoop->wsFlags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ) return;
   sqlite3StrAccumAppend(pStr, " (", 2);
   for(i=0; i<nEq; i++){
-    char *z = aiColumn[i] < 0 ? "rowid" : aCol[aiColumn[i]].zName;
+    const char *z = explainIndexColumnName(pIndex, i);
     if( i ) sqlite3StrAccumAppend(pStr, " AND ", 5);
     sqlite3XPrintf(pStr, 0, i>=nSkip ? "%s=?" : "ANY(%s)", z);
   }
 
   j = i;
   if( pLoop->wsFlags&WHERE_BTM_LIMIT ){
-    char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName;
+    const char *z = explainIndexColumnName(pIndex, i);
     explainAppendTerm(pStr, i++, z, ">");
   }
   if( pLoop->wsFlags&WHERE_TOP_LIMIT ){
-    char *z = aiColumn[j] < 0 ? "rowid" : aCol[aiColumn[j]].zName;
+    const char *z = explainIndexColumnName(pIndex, j);
     explainAppendTerm(pStr, i, z, "<");
   }
   sqlite3StrAccumAppend(pStr, ")", 1);
@@ -1211,7 +1219,12 @@ Bitmask sqlite3WhereCodeOneLoopStart(
       iRowidReg = ++pParse->nMem;
       sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
       sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
-      sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg);  /* Deferred seek */
+      if( pWInfo->eOnePass!=ONEPASS_OFF ){
+        sqlite3VdbeAddOp3(v, OP_NotExists, iCur, 0, iRowidReg);
+        VdbeCoverage(v);
+      }else{
+        sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg);  /* Deferred seek */
+      }
     }else if( iCur!=iIdxCur ){
       Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
       iRowidReg = sqlite3GetTempRange(pParse, pPk->nKeyCol);
diff --git a/src/whereexpr.c b/src/whereexpr.c
index 88eb5b70a..dff425d0e 100644
--- a/src/whereexpr.c
+++ b/src/whereexpr.c
@@ -796,6 +796,51 @@ static Bitmask exprSelectUsage(WhereMaskSet *pMaskSet, Select *pS){
 }
 
 /*
+** Expression pExpr is one operand of a comparison operator that might
+** be useful for indexing.  This routine checks to see if pExpr appears
+** in any index.  Return TRUE (1) if pExpr is an indexed term and return
+** FALSE (0) if not.  If TRUE is returned, also set *piCur to the cursor
+** number of the table that is indexed and *piColumn to the column number
+** of the column that is indexed, or -2 if an expression is being indexed.
+**
+** If pExpr is a TK_COLUMN column reference, then this routine always returns
+** true even if that particular column is not indexed, because the column
+** might be added to an automatic index later.
+*/
+static int exprMightBeIndexed(
+  SrcList *pFrom,        /* The FROM clause */
+  Bitmask mPrereq,       /* Bitmask of FROM clause terms referenced by pExpr */
+  Expr *pExpr,           /* An operand of a comparison operator */
+  int *piCur,            /* Write the referenced table cursor number here */
+  int *piColumn          /* Write the referenced table column number here */
+){
+  Index *pIdx;
+  int i;
+  int iCur;
+  if( pExpr->op==TK_COLUMN ){
+    *piCur = pExpr->iTable;
+    *piColumn = pExpr->iColumn;
+    return 1;
+  }
+  if( mPrereq==0 ) return 0;                 /* No table references */
+  if( (mPrereq&(mPrereq-1))!=0 ) return 0;   /* Refs more than one table */
+  for(i=0; mPrereq>1; i++, mPrereq>>=1){}
+  iCur = pFrom->a[i].iCursor;
+  for(pIdx=pFrom->a[i].pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    if( pIdx->aColExpr==0 ) continue;
+    for(i=0; i<pIdx->nKeyCol; i++){
+      if( pIdx->aiColumn[i]!=(-2) ) continue;
+      if( sqlite3ExprCompare(pExpr, pIdx->aColExpr->a[i].pExpr, iCur)==0 ){
+        *piCur = iCur;
+        *piColumn = -2;
+        return 1;
+      }
+    }
+  }
+  return 0;
+}
+
+/*
 ** The input to this routine is an WhereTerm structure with only the
 ** "pExpr" field filled in.  The job of this routine is to analyze the
 ** subexpression and populate all the other fields of the WhereTerm
@@ -865,16 +910,19 @@ static void exprAnalyze(
   pTerm->iParent = -1;
   pTerm->eOperator = 0;
   if( allowedOp(op) ){
+    int iCur, iColumn;
     Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
     Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
     u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
-    if( pLeft->op==TK_COLUMN ){
-      pTerm->leftCursor = pLeft->iTable;
-      pTerm->u.leftColumn = pLeft->iColumn;
+    if( exprMightBeIndexed(pSrc, prereqLeft, pLeft, &iCur, &iColumn) ){
+      pTerm->leftCursor = iCur;
+      pTerm->u.leftColumn = iColumn;
       pTerm->eOperator = operatorMask(op) & opMask;
     }
     if( op==TK_IS ) pTerm->wtFlags |= TERM_IS;
-    if( pRight && pRight->op==TK_COLUMN ){
+    if( pRight 
+     && exprMightBeIndexed(pSrc, pTerm->prereqRight, pRight, &iCur, &iColumn)
+    ){
       WhereTerm *pNew;
       Expr *pDup;
       u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
@@ -903,8 +951,8 @@ static void exprAnalyze(
       }
       exprCommute(pParse, pDup);
       pLeft = sqlite3ExprSkipCollate(pDup->pLeft);
-      pNew->leftCursor = pLeft->iTable;
-      pNew->u.leftColumn = pLeft->iColumn;
+      pNew->leftCursor = iCur;
+      pNew->u.leftColumn = iColumn;
       testcase( (prereqLeft | extraRight) != prereqLeft );
       pNew->prereqRight = prereqLeft | extraRight;
       pNew->prereqAll = prereqAll;