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If the SQLITE_ENABLE_CURSOR_HINTS macro is defined, then invoke the

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sqlite3BtreeCursorHint() interface to provide hints to the storage engine
about rows that need not be returned.  Hints can be disabled using
SQLITE_TESTCTRL_OPTIMIZATIONS with SQLITE_CursorHints (0x2000).  Cursor
hints are not used by the built-in storage engine of SQLite but might
be useful to applications that provide their own storage engine.  The
current code is work-in-progrss and contains bugs.

FossilOrigin-Name: 3a9bec524ef2de44028b4058e67dc962082888d3
This commit is contained in:
drh
2013-12-07 20:39:19 +00:00
parent 9dcc7cd527
commit 28935364ef
9 changed files with 124 additions and 13 deletions
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21
src/vdbeaux.c
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@@ -639,6 +639,12 @@ static void freeP4(sqlite3 *db, int p4type, void *p4){
if( db->pnBytesFreed==0 ) sqlite3KeyInfoUnref((KeyInfo*)p4);
break;
}
#ifdef SQLITE_ENABLE_CURSOR_HINTS
case P4_EXPR: {
sqlite3ExprDelete(db, (Expr*)p4);
break;
}
#endif
case P4_MPRINTF: {
if( db->pnBytesFreed==0 ) sqlite3_free(p4);
break;
@@ -756,6 +762,15 @@ void sqlite3VdbeChangeP4(Vdbe *p, int addr, const char *zP4, int n){
}else if( n==P4_KEYINFO ){
pOp->p4.p = (void*)zP4;
pOp->p4type = P4_KEYINFO;
#ifdef SQLITE_ENABLE_CURSOR_HINTS
}else if( n==P4_EXPR ){
/* Responsibility for deleting the Expr tree is handed over to the
** VDBE by this operation. The caller should have already invoked
** sqlite3ExprDup() or whatever other routine is needed to make a
** private copy of the tree. */
pOp->p4.pExpr = (Expr*)zP4;
pOp->p4type = P4_EXPR;
#endif
}else if( n==P4_VTAB ){
pOp->p4.p = (void*)zP4;
pOp->p4type = P4_VTAB;
@@ -973,6 +988,12 @@ static char *displayP4(Op *pOp, char *zTemp, int nTemp){
assert( i<nTemp );
break;
}
#ifdef SQLITE_ENABLE_CURSOR_HINTS
case P4_EXPR: {
sqlite3_snprintf(nTemp, zTemp, "(expr)");
break;
}
#endif
case P4_COLLSEQ: {
CollSeq *pColl = pOp->p4.pColl;
sqlite3_snprintf(nTemp, zTemp, "(%.20s)", pColl->zName);