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Take care that the code is not generated for the same Select object more

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than once, as transformations that apply during the first pass might
cause problems for the second pass.
dbsqlfuzz 836b625cd8a41809ef80fc7ebaa6554357bcb463.

FossilOrigin-Name: f30fb19ff763a7cbe768ea49954704e14d6400f69bb4257c9c890e1564e14835
This commit is contained in:
drh
2021-05-26 18:46:51 +00:00
parent 151446e793
commit 14c4d42874
5 changed files with 43 additions and 51 deletions
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18
src/select.c
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@@ -6421,19 +6421,8 @@ int sqlite3Select(
pSub = pItem->pSelect;
if( pSub==0 ) continue;
/* The code for a subquery should only be generated once, though it is
** technically harmless for it to be generated multiple times. The
** following assert() will detect if something changes to cause
** the same subquery to be coded multiple times, as a signal to the
** developers to try to optimize the situation.
**
** Update 2019-07-24:
** See ticket https://sqlite.org/src/tktview/c52b09c7f38903b1311cec40.
** The dbsqlfuzz fuzzer found a case where the same subquery gets
** coded twice. So this assert() now becomes a testcase(). It should
** be very rare, though.
*/
testcase( pItem->addrFillSub!=0 );
/* The code for a subquery should only be generated once. */
assert( pItem->addrFillSub==0 );
/* Increment Parse.nHeight by the height of the largest expression
** tree referred to by this, the parent select. The child select
@@ -6520,14 +6509,13 @@ int sqlite3Select(
sqlite3VdbeAddOp2(v, OP_OpenDup, pItem->iCursor, pPrior->iCursor);
pSub->nSelectRow = pPrior->pSelect->nSelectRow;
}else{
/* Materalize the view. If the view is not correlated, generate a
/* Materialize the view. If the view is not correlated, generate a
** subroutine to do the materialization so that subsequent uses of
** the same view can reuse the materialization. */
int topAddr;
int onceAddr = 0;
int retAddr;
testcase( pItem->addrFillSub==0 ); /* Ticket c52b09c7f38903b1311 */
pItem->regReturn = ++pParse->nMem;
topAddr = sqlite3VdbeAddOp2(v, OP_Integer, 0, pItem->regReturn);
pItem->addrFillSub = topAddr+1;