Avoid preparing a SELECT statement each time an UPDATE or DELETE

by docid is executed against an fts3 table.

FossilOrigin-Name: 9962c10a5c6672bd82b2bf640d878fcdac0b815a

4 files changed, 50 insertions, 23 deletions

diff --git a/ext/fts3/fts3.c b/ext/fts3/fts3.c
index c12e3d215..7c931c42d 100644
--- a/ext/fts3/fts3.c
+++ b/ext/fts3/fts3.c
@@ -492,6 +492,7 @@ static int fts3DisconnectMethod(sqlite3_vtab *pVtab){
   assert( p->pSegments==0 );
 
   /* Free any prepared statements held */
+  sqlite3_finalize(p->pSeekStmt);
   for(i=0; i<SizeofArray(p->aStmt); i++){
     sqlite3_finalize(p->aStmt[i]);
   }
@@ -1681,13 +1682,33 @@ static int fts3OpenMethod(sqlite3_vtab *pVTab, sqlite3_vtab_cursor **ppCsr){
 }
 
 /*
+** Finalize the statement handle at pCsr->pStmt.
+**
+** Or, if that statement handle is one created by fts3CursorSeekStmt(),
+** and the Fts3Table.pSeekStmt slot is currently NULL, save the statement
+** pointer there instead of finalizing it.
+*/
+static void fts3CursorFinalizeStmt(Fts3Cursor *pCsr){
+  if( pCsr->bSeekStmt ){
+    Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
+    if( p->pSeekStmt==0 ){
+      p->pSeekStmt = pCsr->pStmt;
+      sqlite3_reset(pCsr->pStmt);
+      pCsr->pStmt = 0;
+    }
+    pCsr->bSeekStmt = 0;
+  }
+  sqlite3_finalize(pCsr->pStmt);
+}
+
+/*
 ** Close the cursor.  For additional information see the documentation
 ** on the xClose method of the virtual table interface.
 */
 static int fts3CloseMethod(sqlite3_vtab_cursor *pCursor){
   Fts3Cursor *pCsr = (Fts3Cursor *)pCursor;
   assert( ((Fts3Table *)pCsr->base.pVtab)->pSegments==0 );
-  sqlite3_finalize(pCsr->pStmt);
+  fts3CursorFinalizeStmt(pCsr);
   sqlite3Fts3ExprFree(pCsr->pExpr);
   sqlite3Fts3FreeDeferredTokens(pCsr);
   sqlite3_free(pCsr->aDoclist);
@@ -1705,20 +1726,23 @@ static int fts3CloseMethod(sqlite3_vtab_cursor *pCursor){
 **
 ** (or the equivalent for a content=xxx table) and set pCsr->pStmt to
 ** it. If an error occurs, return an SQLite error code.
-**
-** Otherwise, set *ppStmt to point to pCsr->pStmt and return SQLITE_OK.
 */
-static int fts3CursorSeekStmt(Fts3Cursor *pCsr, sqlite3_stmt **ppStmt){
+static int fts3CursorSeekStmt(Fts3Cursor *pCsr){
   int rc = SQLITE_OK;
   if( pCsr->pStmt==0 ){
     Fts3Table *p = (Fts3Table *)pCsr->base.pVtab;
     char *zSql;
-    zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
-    if( !zSql ) return SQLITE_NOMEM;
-    rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
-    sqlite3_free(zSql);
+    if( p->pSeekStmt ){
+      pCsr->pStmt = p->pSeekStmt;
+      p->pSeekStmt = 0;
+    }else{
+      zSql = sqlite3_mprintf("SELECT %s WHERE rowid = ?", p->zReadExprlist);
+      if( !zSql ) return SQLITE_NOMEM;
+      rc = sqlite3_prepare_v2(p->db, zSql, -1, &pCsr->pStmt, 0);
+      sqlite3_free(zSql);
+    }
+    if( rc==SQLITE_OK ) pCsr->bSeekStmt = 1;
   }
-  *ppStmt = pCsr->pStmt;
   return rc;
 }
 
@@ -1730,9 +1754,7 @@ static int fts3CursorSeekStmt(Fts3Cursor *pCsr, sqlite3_stmt **ppStmt){
 static int fts3CursorSeek(sqlite3_context *pContext, Fts3Cursor *pCsr){
   int rc = SQLITE_OK;
   if( pCsr->isRequireSeek ){
-    sqlite3_stmt *pStmt = 0;
-
-    rc = fts3CursorSeekStmt(pCsr, &pStmt);
+    rc = fts3CursorSeekStmt(pCsr);
     if( rc==SQLITE_OK ){
       sqlite3_bind_int64(pCsr->pStmt, 1, pCsr->iPrevId);
       pCsr->isRequireSeek = 0;
@@ -3190,7 +3212,7 @@ static int fts3FilterMethod(
   assert( iIdx==nVal );
 
   /* In case the cursor has been used before, clear it now. */
-  sqlite3_finalize(pCsr->pStmt);
+  fts3CursorFinalizeStmt(pCsr);
   sqlite3_free(pCsr->aDoclist);
   sqlite3Fts3MIBufferFree(pCsr->pMIBuffer);
   sqlite3Fts3ExprFree(pCsr->pExpr);
@@ -3258,7 +3280,7 @@ static int fts3FilterMethod(
       rc = SQLITE_NOMEM;
     }
   }else if( eSearch==FTS3_DOCID_SEARCH ){
-    rc = fts3CursorSeekStmt(pCsr, &pCsr->pStmt);
+    rc = fts3CursorSeekStmt(pCsr);
     if( rc==SQLITE_OK ){
       rc = sqlite3_bind_value(pCsr->pStmt, 1, pCons);
     }
diff --git a/ext/fts3/fts3Int.h b/ext/fts3/fts3Int.h
index 0c86c4217..c3cab9d82 100644
--- a/ext/fts3/fts3Int.h
+++ b/ext/fts3/fts3Int.h
@@ -230,6 +230,7 @@ struct Fts3Table {
   ** statements is run and reset within a single virtual table API call. 
   */
   sqlite3_stmt *aStmt[40];
+  sqlite3_stmt *pSeekStmt;        /* Cache for fts3CursorSeekStmt() */
 
   char *zReadExprlist;
   char *zWriteExprlist;
@@ -299,6 +300,7 @@ struct Fts3Cursor {
   i16 eSearch;                    /* Search strategy (see below) */
   u8 isEof;                       /* True if at End Of Results */
   u8 isRequireSeek;               /* True if must seek pStmt to %_content row */
+  u8 bSeekStmt;                   /* True if pStmt is a seek */
   sqlite3_stmt *pStmt;            /* Prepared statement in use by the cursor */
   Fts3Expr *pExpr;                /* Parsed MATCH query string */
   int iLangid;                    /* Language being queried for */
diff --git a/manifest b/manifest
index cbc9d6ee9..ebac74811 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Typo\sfixes\sin\scomment.\s\sNo\schanges\sto\scode.
-D 2017-02-08T18:13:46.938
+C Avoid\spreparing\sa\sSELECT\sstatement\seach\stime\san\sUPDATE\sor\sDELETE\nby\sdocid\sis\sexecuted\sagainst\san\sfts3\stable.
+D 2017-02-08T19:10:47.175
 F Makefile.in edb6bcdd37748d2b1c3422ff727c748df7ffe918
 F Makefile.linux-gcc 7bc79876b875010e8c8f9502eb935ca92aa3c434
 F Makefile.msc 067a6766f800cc8d72845ab61f8de4ffe8f3fc99
@@ -70,9 +70,9 @@ F ext/fts3/README.content fdc666a70d5257a64fee209f97cf89e0e6e32b51
 F ext/fts3/README.syntax a19711dc5458c20734b8e485e75fb1981ec2427a
 F ext/fts3/README.tokenizers e0a8b81383ea60d0334d274fadf305ea14a8c314
 F ext/fts3/README.txt 8c18f41574404623b76917b9da66fcb0ab38328d
-F ext/fts3/fts3.c 5a8cafedffd101e9946f8909ecf8d34aaa383b4d
+F ext/fts3/fts3.c c4d7eecb12de9749851bcab6e5ca616a5803047a
 F ext/fts3/fts3.h 3a10a0af180d502cecc50df77b1b22df142817fe
-F ext/fts3/fts3Int.h 89d0bd4595a0de384dac78e94b803de12586e8dd
+F ext/fts3/fts3Int.h eb2502000148e80913b965db3e59f29251266d0a
 F ext/fts3/fts3_aux.c 9edc3655fcb287f0467d0a4b886a01c6185fe9f1
 F ext/fts3/fts3_expr.c dfd571a24412779ac01f25c01d888c6ef7b2d0ef
 F ext/fts3/fts3_hash.c 29b986e43f4e9dd40110eafa377dc0d63c422c60
@@ -1555,7 +1555,10 @@ F vsixtest/vsixtest.tcl 6a9a6ab600c25a91a7acc6293828957a386a8a93
 F vsixtest/vsixtest.vcxproj.data 2ed517e100c66dc455b492e1a33350c1b20fbcdc
 F vsixtest/vsixtest.vcxproj.filters 37e51ffedcdb064aad6ff33b6148725226cd608e
 F vsixtest/vsixtest_TemporaryKey.pfx e5b1b036facdb453873e7084e1cae9102ccc67a0
-P 77b470b0df73dc5ae5ad2f0170ef7c50558c7c88
-R 52473535d67a86108597185ae6d56e08
-U mistachkin
-Z 77244f34774b49c249d3e5a9b6027fee
+P c09dd5c0befaf5028abfead8114bd74a30ffe5d4
+R fbd7643b7e0c4a3c885d2a6aeb5fecfa
+T *branch * fts3-seekstmt-cache
+T *sym-fts3-seekstmt-cache *
+T -sym-trunk *
+U dan
+Z dc34c96dc2a3bdce03fc410bb45d9619
diff --git a/manifest.uuid b/manifest.uuid
index 0e6917c22..a8184cc91 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-c09dd5c0befaf5028abfead8114bd74a30ffe5d4
\ No newline at end of file
+9962c10a5c6672bd82b2bf640d878fcdac0b815a
\ No newline at end of file