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For the OP_SeekScan optimization, the OP_IdxGT does not necessarily come

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right after the OP_SeekGE.   So use the P2 operand of OP_SeekScan to point
to the first instruction after OP_IdxGT.  Problem found by dbsqlfuzz.

FossilOrigin-Name: 091d71939411bf2079098f09ddc0525f11f380119fd27114e2b3eec9a8ac0db4
This commit is contained in:
drh
2020-10-02 11:55:07 +00:00
parent 4ad1a1c74c
commit 04e70ce07d
4 changed files with 30 additions and 22 deletions
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31
src/vdbe.c
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@@ -4384,18 +4384,18 @@ seek_not_found:
}
/* Opcode: SeekScan P1 * * * *
/* Opcode: SeekScan P1 P2 * * *
** Synopsis: Scan-ahead up to P1 rows
**
** This opcode is a prefix opcode to OP_SeekGE. In other words, this
** opcode must be immediately followed by OP_SeekGE. Furthermore, the
** OP_SeekGE must be followed by OP_IdxGT. These constraints are
** opcode must be immediately followed by OP_SeekGE. This constraint is
** checked by assert() statements.
**
** This opcode uses the P1 through P4 operands of the subsequent
** OP_SeekGE. In the text that follows, the operands of the subsequent
** OP_SeekGE opcode are denoted as SeekOP.P1 through SeekOP.P4. Only
** the P1 operand of this opcode is used, and it is denoted as This.P1.
** the P1 and P2 operands of this opcode are also used, and are called
** This.P1 and This.P2.
**
** This opcode helps to optimize IN operators on a multi-column index
** where the IN operator is on the later terms of the index by avoiding
@@ -4413,7 +4413,7 @@ seek_not_found:
** If the SeekGE.P1 cursor is pointing to a valid row, then that row
** might be the target row, or it might be near and slightly before the
** target row. This opcode attempts to position the cursor on the target
** row by, perhaps stepping by invoking sqlite3BtreeStep() on the cursor
** row by, perhaps by invoking sqlite3BtreeStep() on the cursor
** between 0 and This.P1 times.
**
** There are three possible outcomes from this opcode:<ol>
@@ -4423,8 +4423,8 @@ seek_not_found:
** then fall through into the subsquence OP_SeekGE opcode.
**
** <li> If the cursor is successfully moved to the target row by 0 or more
** sqlite3BtreeNext() calls, then jump to the first instruction after the
** OP_IdxGT opcode - or in other words, skip the next two opcodes.
** sqlite3BtreeNext() calls, then jump to This.P2, which will land just
** past the OP_IdxGT opcode that follows the OP_SeekGE.
**
** <li> If the cursor ends up past the target row (indicating the the target
** row does not exist in the btree) then jump to SeekOP.P2.
@@ -4437,11 +4437,16 @@ case OP_SeekScan: {
UnpackedRecord r;
assert( pOp[1].opcode==OP_SeekGE );
assert( pOp[2].opcode==OP_IdxGT );
assert( pOp[1].p1==pOp[2].p1 );
assert( pOp[1].p2==pOp[2].p2 );
assert( pOp[1].p3==pOp[2].p3 );
assert( pOp[1].p4.i==pOp[2].p4.i );
/* pOp->p2 points to the first instruction past the OP_IdxGT that
** follows the OP_SeekGE. */
assert( pOp->p2>=(int)(pOp-aOp)+2 );
assert( aOp[pOp->p2-1].opcode==OP_IdxGT );
assert( pOp[1].p1==aOp[pOp->p2-1].p1 );
assert( pOp[1].p2==aOp[pOp->p2-1].p2 );
assert( pOp[1].p3==aOp[pOp->p2-1].p3 );
assert( pOp[1].p4.i==aOp[pOp->p2-1].p4.i );
assert( pOp->p1>0 );
pC = p->apCsr[pOp[1].p1];
assert( pC!=0 );
@@ -4492,7 +4497,7 @@ case OP_SeekScan: {
}
#endif
VdbeBranchTaken(2,3);
pOp += 2;
goto jump_to_p2;
break;
}
if( nStep<=0 ){