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Add the OP_IfNoHope and OP_SeekHit opcodes used to reduce the number of

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unnecessary sqlite3BtreeMovetoUnpacked() calls when checking for an early
exit on IN-operator loops.  Futher optimizations are likely possible here.

FossilOrigin-Name: 6bf251af4347165a470d39457d61ab6d2a06c206db8f30bd8be5dbb388ae8a5b
This commit is contained in:
drh
2018-06-05 20:45:20 +00:00
parent 86d0ea7558
commit 8c2b6d784b
6 changed files with 74 additions and 12 deletions
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56
src/vdbe.c
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@@ -4034,6 +4034,25 @@ seek_not_found:
break;
}
/* Opcode: SeekHit P1 P2 * * *
** Synopsis: seekHit=P2
**
** Set the seekHit flag on cursor P1 to the value in P2.
** The seekHit flag is used by the IfNoHope opcode.
**
** P1 must be a valid b-tree cursor. P2 must be a boolean value,
** either 0 or 1.
*/
case OP_SeekHit: {
VdbeCursor *pC;
assert( pOp->p1>=0 && pOp->p1<p->nCursor );
pC = p->apCsr[pOp->p1];
assert( pC!=0 );
assert( pOp->p2==0 || pOp->p2==1 );
pC->seekHit = pOp->p2 & 1;
break;
}
/* Opcode: Found P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
@@ -4068,7 +4087,34 @@ seek_not_found:
** advanced in either direction. In other words, the Next and Prev
** opcodes do not work after this operation.
**
** See also: Found, NotExists, NoConflict
** See also: Found, NotExists, NoConflict, IfNoHope
*/
/* Opcode: IfNoHope P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
**
** Register P3 is the first of P4 registers that form an unpacked
** record.
**
** Cursor P1 is on an index btree. If the seekHit flag is set on P1, then
** this opcode is a no-op. But if the seekHit flag of P1 is clear, then
** check to see if there is any entry in P1 that matches the
** prefix identified by P3 and P4. If no entry matches the prefix,
** jump to P2. Otherwise fall through.
**
** This opcode behaves like OP_NotFound if the seekHit
** flag is clear and it behaves like OP_Noop if the seekHit flag is set.
**
** This opcode is used in IN clause processing for a multi-column key.
** If an IN clause is attached to an element of the key other than the
** left-most element, and if there are no matches on the most recent
** seek over the whole key, then it might be that one of the key element
** to the left is prohibiting a match, and hence there is "no hope" of
** any match regardless of how many IN clause elements are checked.
** In such a case, we abandon the IN clause search early, using this
** opcode. The opcode name comes from the fact that the
** jump is taken if there is "no hope" of achieving a match.
**
** See also: NotFound, SeekHit
*/
/* Opcode: NoConflict P1 P2 P3 P4 *
** Synopsis: key=r[P3@P4]
@@ -4093,6 +4139,14 @@ seek_not_found:
**
** See also: NotFound, Found, NotExists
*/
case OP_IfNoHope: { /* jump, in3 */
VdbeCursor *pC;
assert( pOp->p1>=0 && pOp->p1<p->nCursor );
pC = p->apCsr[pOp->p1];
assert( pC!=0 );
if( pC->seekHit ) break;
/* Fall through into OP_NotFound */
}
case OP_NoConflict: /* jump, in3 */
case OP_NotFound: /* jump, in3 */
case OP_Found: { /* jump, in3 */