Add code to handle recursive CTEs.

FossilOrigin-Name: a5c2a54a07d35166911abc792008c05dea897742

9 files changed, 262 insertions, 33 deletions

diff --git a/manifest b/manifest
index a1a39b1a6..56fe478fb 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Fix\ssome\smemory\sleaks\sand\scrashes\sthat\scould\sfollow\san\sOOM\scondition\sduring\sWITH\sclause\sparsing.
-D 2014-01-13T16:36:40.215
+C Add\scode\sto\shandle\srecursive\sCTEs.
+D 2014-01-14T20:14:09.053
 F Makefile.arm-wince-mingw32ce-gcc d6df77f1f48d690bd73162294bbba7f59507c72f
 F Makefile.in 2ef13430cd359f7b361bb863504e227b25cc7f81
 F Makefile.linux-gcc 91d710bdc4998cb015f39edf3cb314ec4f4d7e23
@@ -166,7 +166,7 @@ F src/auth.c 523da7fb4979469955d822ff9298352d6b31de34
 F src/backup.c a729e63cf5cd1829507cb7b8e89f99b95141bb53
 F src/bitvec.c 19a4ba637bd85f8f63fc8c9bae5ade9fb05ec1cb
 F src/btmutex.c 976f45a12e37293e32cae0281b15a21d48a8aaa7
-F src/btree.c 11e29ef8cf16a42925fde036bcffbeffd9cc82df
+F src/btree.c c15e1722696b66c4029c487acfb830b0985bf142
 F src/btree.h a61ddebc78c66795a2b93181321a116746302cc9
 F src/btreeInt.h f038e818bfadf75afbd09819ed93c26a333d39e0
 F src/build.c 5a2daa6649640711ca60114046903be932348e52
@@ -175,7 +175,7 @@ F src/complete.c dc1d136c0feee03c2f7550bafc0d29075e36deac
 F src/ctime.c 77779efbe78dd678d84bfb4fc2e87b6b6ad8dccd
 F src/date.c 593c744b2623971e45affd0bde347631bdfa4625
 F src/delete.c 91e1321021db5dc266360531b8b6550009d771ff
-F src/expr.c de86bf987c532ec9d63fb1bf8a6eb6ec2cf5ba69
+F src/expr.c fee4b54fdcf5a979e6f5012da3dfb084ac5d3aac
 F src/fault.c 160a0c015b6c2629d3899ed2daf63d75754a32bb
 F src/fkey.c 2ab0f5384b70594468ef3ac5c7ed8ca24bfd17d5
 F src/func.c 6325ac2ec10833ccf4d5c36d323709221d37ea19
@@ -219,12 +219,12 @@ F src/printf.c 85d07756e45d7496d19439dcae3e6e9e0090f269
 F src/random.c d10c1f85b6709ca97278428fd5db5bbb9c74eece
 F src/resolve.c 7eda9097b29fcf3d2b42fdc17d1de672134e09b6
 F src/rowset.c 64655f1a627c9c212d9ab497899e7424a34222e0
-F src/select.c 9dc9177bfb9278a603e3835e828ff60ec68fba6f
+F src/select.c 0f7779b0c1c317dcac0f65f695d036030c16775f
 F src/shell.c a3541193d5fce37e91dad8ef46a9505aa7c9b344
 F src/sqlite.h.in d94a8b89522f526ba711182ee161e06f8669bcc9
 F src/sqlite3.rc 11094cc6a157a028b301a9f06b3d03089ea37c3e
 F src/sqlite3ext.h 886f5a34de171002ad46fae8c36a7d8051c190fc
-F src/sqliteInt.h a350bcf6d62204b6b4720ce1922c95a575a0b5ad
+F src/sqliteInt.h fc7b2516260c4e14bd4342cd9ed47f3d0ca27cc5
 F src/sqliteLimit.h 164b0e6749d31e0daa1a4589a169d31c0dec7b3d
 F src/status.c 7ac05a5c7017d0b9f0b4bcd701228b784f987158
 F src/table.c 2cd62736f845d82200acfa1287e33feb3c15d62e
@@ -280,7 +280,7 @@ F src/update.c c2706a6eb232a96345c35b7e1e75a188e26812bb
 F src/utf.c 6fc6c88d50448c469c5c196acf21617a24f90269
 F src/util.c e71f19b272f05c8695cf747b4bac1732685f9e5c
 F src/vacuum.c 3728d74919d4fb1356f9e9a13e27773db60b7179
-F src/vdbe.c b110887e415b5d2af58c2374c4dfdcf774c5d46c
+F src/vdbe.c 9b918126afb9a7b7ad232db7453680c7ef5821a4
 F src/vdbe.h e6c4c610fcabad4fa80ebb1efc6822a9367e2b26
 F src/vdbeInt.h 42db251e9f863401ff847b90d5fe1614c89a6a56
 F src/vdbeapi.c ce4e68ea4842cc6081046f533d088dcf01d247ad
@@ -293,7 +293,7 @@ F src/vtab.c 21b932841e51ebd7d075e2d0ad1415dce8d2d5fd
 F src/wal.c 7dc3966ef98b74422267e7e6e46e07ff6c6eb1b4
 F src/wal.h df01efe09c5cb8c8e391ff1715cca294f89668a4
 F src/walker.c e9e593d5bb798c3e67fc3893dfe7055c9e7d8d74
-F src/where.c 18f07fd0fd116a5880773c689eb7cd8e60175107
+F src/where.c 830b42f452cfbc4e17582f6c1d388e15b379b833
 F src/whereInt.h 96a75c61f1d2b9d4a8e4bb17d89deb0cf7cba358
 F test/8_3_names.test ebbb5cd36741350040fd28b432ceadf495be25b2
 F test/aggerror.test a867e273ef9e3d7919f03ef4f0e8c0d2767944f2
@@ -1091,7 +1091,7 @@ F test/wild001.test bca33f499866f04c24510d74baf1e578d4e44b1c
 F test/win32heap.test ea19770974795cff26e11575e12d422dbd16893c
 F test/win32lock.test 7a6bd73a5dcdee39b5bb93e92395e1773a194361
 F test/win32longpath.test 169c75a3b2e43481f4a62122510210c67b08f26d
-F test/with1.test fb8409a35b1314be6e73a87597322f3369b59b2b
+F test/with1.test 12a6661eabcc9ae299020f7b4197a75a9c084748
 F test/withM.test ac3ec7ee0b33a02d0fa15da91214d97ddea64e34
 F test/without_rowid1.test aaa26da19d543cd8d3d2d0e686dfa255556c15c8
 F test/without_rowid2.test af260339f79d13cb220288b67cd287fbcf81ad99
@@ -1150,7 +1150,7 @@ F tool/vdbe-compress.tcl 0cf56e9263a152b84da86e75a5c0cdcdb7a47891
 F tool/warnings-clang.sh f6aa929dc20ef1f856af04a730772f59283631d4
 F tool/warnings.sh d1a6de74685f360ab718efda6265994b99bbea01
 F tool/win/sqlite.vsix 030f3eeaf2cb811a3692ab9c14d021a75ce41fff
-P a26f399ba485e8127c276c5f103ec6c555e11734
-R 7e06730d3714a8aceb489d831c2bc18d
+P 8839850c44a8938883e493eacd752fa686e542df
+R 1d5d9f6beb143e76aa04b4bf9953f5da
 U dan
-Z 780f0749f7ee296248db4bd00ffb23e3
+Z 1616366ca894deb1473f9b1eb1563ebc
diff --git a/manifest.uuid b/manifest.uuid
index 6382ccbc9..f994f09e9 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-8839850c44a8938883e493eacd752fa686e542df
\ No newline at end of file
+a5c2a54a07d35166911abc792008c05dea897742
\ No newline at end of file
diff --git a/src/btree.c b/src/btree.c
index 20bed057e..e28a97c84 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -7350,6 +7350,7 @@ static int clearDatabasePage(
   int rc;
   unsigned char *pCell;
   int i;
+  int hdr;
 
   assert( sqlite3_mutex_held(pBt->mutex) );
   if( pgno>btreePagecount(pBt) ){
@@ -7358,6 +7359,7 @@ static int clearDatabasePage(
 
   rc = getAndInitPage(pBt, pgno, &pPage, 0);
   if( rc ) return rc;
+  hdr = pPage->hdrOffset;
   for(i=0; i<pPage->nCell; i++){
     pCell = findCell(pPage, i);
     if( !pPage->leaf ){
@@ -7368,7 +7370,7 @@ static int clearDatabasePage(
     if( rc ) goto cleardatabasepage_out;
   }
   if( !pPage->leaf ){
-    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[8]), 1, pnChange);
+    rc = clearDatabasePage(pBt, get4byte(&pPage->aData[hdr+8]), 1, pnChange);
     if( rc ) goto cleardatabasepage_out;
   }else if( pnChange ){
     assert( pPage->intKey );
@@ -7377,7 +7379,7 @@ static int clearDatabasePage(
   if( freePageFlag ){
     freePage(pPage, &rc);
   }else if( (rc = sqlite3PagerWrite(pPage->pDbPage))==0 ){
-    zeroPage(pPage, pPage->aData[0] | PTF_LEAF);
+    zeroPage(pPage, pPage->aData[hdr] | PTF_LEAF);
   }
 
 cleardatabasepage_out:
diff --git a/src/expr.c b/src/expr.c
index d0ea28002..e271e4679 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -1055,6 +1055,7 @@ Select *sqlite3SelectDup(sqlite3 *db, Select *p, int flags){
   pNew->addrOpenEphm[1] = -1;
   pNew->addrOpenEphm[2] = -1;
   pNew->pWith = withDup(db, p->pWith);
+  pNew->pRecurse = p->pRecurse;
   return pNew;
 }
 #else
diff --git a/src/select.c b/src/select.c
index b054489b0..0db4b0180 100644
--- a/src/select.c
+++ b/src/select.c
@@ -691,12 +691,26 @@ static void selectInnerLoop(
 
     /* Store the result as data using a unique key.
     */
+    case SRT_DistTable:
     case SRT_Table:
     case SRT_EphemTab: {
       int r1 = sqlite3GetTempReg(pParse);
       testcase( eDest==SRT_Table );
       testcase( eDest==SRT_EphemTab );
       sqlite3VdbeAddOp3(v, OP_MakeRecord, regResult, nColumn, r1);
+#ifndef SQLITE_OMIT_CTE
+      if( eDest==SRT_DistTable ){
+        /* If the destination is DistTable, then cursor (iParm+1) is open
+        ** on an ephemeral index. If the current row is already present
+        ** in the index, do not write it to the output. If not, add the
+        ** current row to the index and proceed with writing it to the
+        ** output table as well.  */
+        int addr = sqlite3VdbeCurrentAddr(v) + 4;
+        sqlite3VdbeAddOp4Int(v, OP_Found, iParm+1, addr, r1, 0);
+        sqlite3VdbeAddOp2(v, OP_IdxInsert, iParm+1, r1);
+        assert( pOrderBy==0 );
+      }
+#endif
       if( pOrderBy ){
         pushOntoSorter(pParse, pOrderBy, p, r1);
       }else{
@@ -1729,6 +1743,7 @@ static int multiSelect(
   ** the last (right-most) SELECT in the series may have an ORDER BY or LIMIT.
   */
   assert( p && p->pPrior );  /* Calling function guarantees this much */
+  assert( p->pRecurse==0 || p->op==TK_ALL || p->op==TK_UNION );
   db = pParse->db;
   pPrior = p->pPrior;
   assert( pPrior->pRightmost!=pPrior );
@@ -1774,12 +1789,82 @@ static int multiSelect(
     goto multi_select_end;
   }
 
+  /* If this is a recursive query, check that there is no ORDER BY or
+  ** LIMIT clause. Neither of these are supported.  */
+  assert( p->pOffset==0 || p->pLimit );
+  if( p->pRecurse && (p->pOrderBy || p->pLimit) ){
+    sqlite3ErrorMsg(pParse, "%s in a recursive query is not allowed",
+        p->pOrderBy ? "ORDER BY" : "LIMIT"
+    );
+    goto multi_select_end;
+  }
+
   /* Compound SELECTs that have an ORDER BY clause are handled separately.
   */
   if( p->pOrderBy ){
     return multiSelectOrderBy(pParse, p, pDest);
   }
 
+#ifndef SQLITE_OMIT_CTE
+  if( p->pRecurse ){
+    int nCol = p->pEList->nExpr;
+    int addrNext;
+    int addrSwap;
+    int iCont, iBreak;
+    int tmp1, tmp2;               /* Cursors used to access temporary tables */
+    int tmp3 = 0;                 /* To ensure unique results if UNION */
+    int eDest = SRT_Table;
+    SelectDest tmp2dest;
+
+    iBreak = sqlite3VdbeMakeLabel(v);
+    iCont = sqlite3VdbeMakeLabel(v);
+
+    tmp1 = pParse->nTab++;
+    tmp2 = pParse->nTab++;
+    if( p->op==TK_UNION ){
+      eDest = SRT_DistTable;
+      tmp3 = pParse->nTab++;
+    }
+    sqlite3SelectDestInit(&tmp2dest, eDest, tmp2);
+
+    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tmp1, nCol);
+    sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tmp2, nCol);
+    if( tmp3 ){
+      p->addrOpenEphm[0] = sqlite3VdbeAddOp2(v, OP_OpenEphemeral, tmp3, 0);
+      p->selFlags |= SF_UsesEphemeral;
+    }
+
+    /* Store the results of the initial SELECT in tmp2. */
+    rc = sqlite3Select(pParse, pPrior, &tmp2dest);
+    if( rc ) goto multi_select_end;
+
+    /* Clear tmp1. Then switch the contents of tmp1 and tmp2. Then teturn 
+    ** the contents of tmp1 to the caller. Or, if tmp1 is empty at this
+    ** point, the recursive query has finished - jump to address iBreak.  */
+    addrSwap = sqlite3VdbeAddOp2(v, OP_SwapCursors, tmp1, tmp2);
+    sqlite3VdbeAddOp2(v, OP_Rewind, tmp1, iBreak);
+    addrNext = sqlite3VdbeCurrentAddr(v);
+    selectInnerLoop(pParse, p, p->pEList, tmp1, p->pEList->nExpr,
+        0, 0, &dest, iCont, iBreak);
+    sqlite3VdbeResolveLabel(v, iCont);
+    sqlite3VdbeAddOp2(v, OP_Next, tmp1, addrNext);
+
+    /* Execute the recursive SELECT. Store the results in tmp2. While this
+    ** SELECT is running, the contents of tmp1 are read by recursive 
+    ** references to the current CTE.  */
+    p->pPrior = 0;
+    p->pRecurse->tnum = tmp1;
+    p->pRecurse->tabFlags |= TF_Recursive;
+    rc = sqlite3Select(pParse, p, &tmp2dest);
+    p->pRecurse->tabFlags &= ~TF_Recursive;
+    p->pPrior = pPrior;
+    if( rc ) goto multi_select_end;
+
+    sqlite3VdbeAddOp2(v, OP_Goto, 0, addrSwap);
+    sqlite3VdbeResolveLabel(v, iBreak);
+  }else
+#endif
+
   /* Generate code for the left and right SELECT statements.
   */
   switch( p->op ){
@@ -3449,6 +3534,73 @@ static void ctePop(Parse *pParse, struct Cte *pCte){
   }
 }
 
+static int withExpand(
+  Walker *pWalker, 
+  struct SrcList_item *pFrom,
+  struct Cte *pCte
+){
+  Table *pTab;
+  Parse *pParse = pWalker->pParse;
+  sqlite3 *db = pParse->db;
+
+  assert( pFrom->pSelect==0 );
+  assert( pFrom->pTab==0 );
+
+  if( pCte==pParse->pCte && (pTab = pCte->pTab) ){
+    /* This is the recursive part of a recursive CTE */
+    pFrom->pTab = pTab;
+    pTab->nRef++;
+  }else{
+    ExprList *pEList;
+    Select *pSel;
+    int bRecursive;
+
+    pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
+    if( pTab==0 ) return WRC_Abort;
+    pTab->nRef = 1;
+    pTab->zName = sqlite3MPrintf(db, "sqlite_sq_%p", (void*)pTab);
+    pTab->iPKey = -1;
+    pTab->nRowEst = 1048576;
+    pTab->tabFlags |= TF_Ephemeral;
+    pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0);
+    if( db->mallocFailed ) return SQLITE_NOMEM;
+    assert( pFrom->pSelect );
+
+    if( ctePush(pParse, pCte) ) return WRC_Abort;
+    pSel = pFrom->pSelect;
+    bRecursive = (pSel->op==TK_ALL || pSel->op==TK_UNION);
+    if( bRecursive ){
+      assert( pSel->pPrior );
+      sqlite3WalkSelect(pWalker, pSel->pPrior);
+    }else{
+      sqlite3WalkSelect(pWalker, pSel);
+    }
+
+    if( pCte->pCols ){
+      pEList = pCte->pCols;
+    }else{
+      Select *pLeft;
+      for(pLeft=pSel; pLeft->pPrior; pLeft=pLeft->pPrior);
+      pEList = pLeft->pEList;
+    }
+    selectColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol);
+
+    if( bRecursive ){
+      int nRef = pTab->nRef;
+      pCte->pTab = pTab;
+      sqlite3WalkSelect(pWalker, pSel);
+      pCte->pTab = 0;
+      if( pTab->nRef > nRef){
+        pSel->pRecurse = pTab;
+        assert( pTab->tnum==0 );
+      }
+    }
+
+    ctePop(pParse, pCte);
+  }
+
+  return SQLITE_OK;
+}
 
 /*
 ** This routine is a Walker callback for "expanding" a SELECT statement.
@@ -3515,31 +3667,22 @@ static int selectExpander(Walker *pWalker, Select *p){
 #ifndef SQLITE_OMIT_CTE
     pCte = searchWith(pParse, pFrom);
     if( pCte ){
-      pFrom->pSelect = sqlite3SelectDup(db, pCte->pSelect, 0);
-      if( pFrom->pSelect==0 ) return WRC_Abort;
-    }
+      if( withExpand(pWalker, pFrom, pCte) ) return WRC_Abort;
+    }else
 #endif
-    if( pFrom->zName==0 || pCte ){
+    if( pFrom->zName==0 ){
 #ifndef SQLITE_OMIT_SUBQUERY
-      ExprList *pEList;
       Select *pSel = pFrom->pSelect;
       /* A sub-query in the FROM clause of a SELECT */
       assert( pSel!=0 );
       assert( pFrom->pTab==0 );
-      if( ctePush(pParse, pCte) ) return WRC_Abort;
       sqlite3WalkSelect(pWalker, pSel);
-      ctePop(pParse, pCte);
       pFrom->pTab = pTab = sqlite3DbMallocZero(db, sizeof(Table));
       if( pTab==0 ) return WRC_Abort;
       pTab->nRef = 1;
       pTab->zName = sqlite3MPrintf(db, "sqlite_sq_%p", (void*)pTab);
       while( pSel->pPrior ){ pSel = pSel->pPrior; }
-      if( pCte && pCte->pCols ){
-        pEList = pCte->pCols;
-      }else{
-        pEList = pSel->pEList;
-      }
-      selectColumnsFromExprList(pParse, pEList, &pTab->nCol, &pTab->aCol);
+      selectColumnsFromExprList(pParse, pSel->pEList, &pTab->nCol, &pTab->aCol);
       pTab->iPKey = -1;
       pTab->nRowEst = 1048576;
       pTab->tabFlags |= TF_Ephemeral;
@@ -3831,9 +3974,10 @@ static int selectAddSubqueryTypeInfo(Walker *pWalker, Select *p){
       if( ALWAYS(pTab!=0) && (pTab->tabFlags & TF_Ephemeral)!=0 ){
         /* A sub-query in the FROM clause of a SELECT */
         Select *pSel = pFrom->pSelect;
-        assert( pSel );
-        while( pSel->pPrior ) pSel = pSel->pPrior;
-        selectAddColumnTypeAndCollation(pParse, pTab, pSel);
+        if( pSel ){
+          while( pSel->pPrior ) pSel = pSel->pPrior;
+          selectAddColumnTypeAndCollation(pParse, pTab, pSel);
+        }
       }
     }
   }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 6bd65592b..c7f0609ba 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -1429,7 +1429,7 @@ struct Table {
 };
 
 /*
-** Allowed values for Tabe.tabFlags.
+** Allowed values for Table.tabFlags.
 */
 #define TF_Readonly        0x01    /* Read-only system table */
 #define TF_Ephemeral       0x02    /* An ephemeral table */
@@ -1437,6 +1437,7 @@ struct Table {
 #define TF_Autoincrement   0x08    /* Integer primary key is autoincrement */
 #define TF_Virtual         0x10    /* Is a virtual table */
 #define TF_WithoutRowid    0x20    /* No rowid used. PRIMARY KEY is the key */
+#define TF_Recursive       0x40    /* Recursive reference within CTE */
 
 
 /*
@@ -2129,6 +2130,7 @@ struct NameContext {
 */
 struct Select {
   ExprList *pEList;      /* The fields of the result */
+  Table *pRecurse;       /* Non-NULL for the recursive part of recursive CTE */
   u8 op;                 /* One of: TK_UNION TK_ALL TK_INTERSECT TK_EXCEPT */
   u16 selFlags;          /* Various SF_* values */
   int iLimit, iOffset;   /* Memory registers holding LIMIT & OFFSET counters */
@@ -2182,6 +2184,7 @@ struct Select {
 #define SRT_Table        8  /* Store result as data with an automatic rowid */
 #define SRT_EphemTab     9  /* Create transient tab and store like SRT_Table */
 #define SRT_Coroutine   10  /* Generate a single row of result */
+#define SRT_DistTable   11  /* Like SRT_TABLE, but unique results only */
 
 /*
 ** An instance of this object describes where to put of the results of
@@ -2647,6 +2650,7 @@ struct With {
     ExprList *pCols;              /* List of explicit column names, or NULL */
     Select *pSelect;              /* The contents of the CTE */
     struct Cte *pOuterCte;
+    Table *pTab;
   } a[1];
 };
 
diff --git a/src/vdbe.c b/src/vdbe.c
index 286bc45ba..ffb4dd19b 100644
--- a/src/vdbe.c
+++ b/src/vdbe.c
@@ -3369,6 +3369,53 @@ case OP_OpenEphemeral: {
   break;
 }
 
+/* Opcode: OpenEphreader P1 P2 * * *
+**
+** P2 is a cursor opened by the OpenEphemeral opcode. This opcode opens
+** a new read-only cursor named P1 that accesses the same epheremal table 
+** as P2.
+*/
+case OP_OpenEphreader: {
+  VdbeCursor *pEph;
+  VdbeCursor *pCx;
+  Pgno pgno;
+
+  pEph = p->apCsr[pOp->p2];
+  pCx = allocateCursor(p, pOp->p1, pEph->nField, -1, 1);
+  if( pCx==0 ) goto no_mem;
+  pCx->nullRow = 1;
+  pCx->pKeyInfo = pEph->pKeyInfo;
+  pCx->isTable = pEph->isTable;
+  pCx->isOrdered = pEph->isOrdered;
+  pgno = MASTER_ROOT + !pCx->isTable;
+  rc = sqlite3BtreeCursor(pEph->pBt, pgno, 0, pCx->pKeyInfo, pCx->pCursor);
+  break;
+}
+
+/* Opcode: SwapCursors P1 P2 * * *
+**
+** Parameters P1 and P2 are both cursors opened by the OpenEphemeral
+** opcode. This opcode deletes the contents of epheremal table P1,
+** then renames P2 to P1 and P1 to P2. In other words, following this
+** opcode cursor P2 is open on an empty table and P1 is open on the
+** table that was initially accessed by P2.
+*/
+case OP_SwapCursors: {
+  Mem tmp;
+  VdbeCursor *pTmp;
+
+  tmp = p->aMem[p->nMem - pOp->p1];
+  p->aMem[p->nMem - pOp->p1] = p->aMem[p->nMem - pOp->p2];
+  p->aMem[p->nMem - pOp->p2] = tmp;
+
+  pTmp = p->apCsr[pOp->p1];
+  p->apCsr[pOp->p1] = p->apCsr[pOp->p2];
+  p->apCsr[pOp->p2] = pTmp;
+
+  rc = sqlite3BtreeClearTable(pTmp->pBt, MASTER_ROOT + !pTmp->isTable, 0);
+  break;
+}
+
 /* Opcode: SorterOpen P1 * * P4 *
 **
 ** This opcode works like OP_OpenEphemeral except that it opens
diff --git a/src/where.c b/src/where.c
index d5444a605..8827faa83 100644
--- a/src/where.c
+++ b/src/where.c
@@ -5653,7 +5653,11 @@ WhereInfo *sqlite3WhereBegin(
     iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
     pLoop = pLevel->pWLoop;
     if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
-      /* Do nothing */
+      if( pTab->tabFlags & TF_Recursive ){
+        int iCur = pTabItem->iCursor;
+        sqlite3VdbeAddOp2(v, OP_OpenEphreader, iCur, pTab->tnum);
+      }
+      /* Otherwise do nothing */
     }else
 #ifndef SQLITE_OMIT_VIRTUALTABLE
     if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
diff --git a/test/with1.test b/test/with1.test
index 0b7810ebd..3dd8c47ea 100644
--- a/test/with1.test
+++ b/test/with1.test
@@ -137,6 +137,33 @@ do_execsql_test 4.3 {
   SELECT * FROM t1;
 } {1 3 8 9}
 
+#-------------------------------------------------------------------------
+#
+do_execsql_test 5.1 {
+  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i)
+  SELECT x FROM i LIMIT 10;
+} {1 2 3 4 5 6 7 8 9 10}
+
+do_catchsql_test 5.2 {
+  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i ORDER BY 1)
+  SELECT x FROM i LIMIT 10;
+} {1 {ORDER BY in a recursive query is not allowed}}
+
+do_catchsql_test 5.3 {
+  WITH i(x) AS ( VALUES(1) UNION ALL SELECT x+1 FROM i LIMIT 10 )
+  SELECT x FROM i LIMIT 10;
+} {1 {LIMIT in a recursive query is not allowed}}
+
+do_execsql_test 5.4 {
+  WITH i(x) AS ( VALUES(1) UNION ALL SELECT (x+1)%10 FROM i)
+  SELECT x FROM i LIMIT 20;
+} {1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0}
+
+do_execsql_test 5.5 {
+  WITH i(x) AS ( VALUES(1) UNION SELECT (x+1)%10 FROM i)
+  SELECT x FROM i LIMIT 20;
+} {1 2 3 4 5 6 7 8 9 0}
+
 finish_test