database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-06-13 07:41:39 +03:00
Code Activity

Fix cross-type case in partial row matching for hashed subplans.

Browse Source 
When hashing a subplan like "WHERE (a, b) NOT IN (SELECT x, y FROM ...)",
findPartialMatch() attempted to match rows using the hashtable's internal
equality operators, which of course are for x and y's datatypes.  What we
need to use are the potentially cross-type operators for a=x, b=y, etc.
Failure to do that leads to wrong answers or even crashes.  The scope for
problems is limited to cases where we have different types with compatible
hash functions (else we'd not be using a hashed subplan), but for example
int4 vs int8 can cause the problem.

Per bug #7597 from Bo Jensen.  This has been wrong since the hashed-subplan
code was written, so patch all the way back.
This commit is contained in:
Tom Lane
2012-10-11 12:20:56 -04:00
parent 6f60fdd701
commit 4816d2ea32
3 changed files with 43 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

17
src/backend/executor/nodeSubplan.c
View File

@ -46,7 +46,8 @@ static Datum ExecScanSubPlan(SubPlanState *node,
ExprContext *econtext,
bool *isNull);
static void buildSubPlanHash(SubPlanState *node, ExprContext *econtext);
static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot);
static bool findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
FmgrInfo *eqfunctions);
static bool slotAllNulls(TupleTableSlot *slot);
static bool slotNoNulls(TupleTableSlot *slot);
@ -153,7 +154,7 @@ ExecHashSubPlan(SubPlanState *node,
return BoolGetDatum(true);
}
if (node->havenullrows &&
findPartialMatch(node->hashnulls, slot))
findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs))
{
ExecClearTuple(slot);
*isNull = true;
@ -186,14 +187,14 @@ ExecHashSubPlan(SubPlanState *node,
}
/* Scan partly-null table first, since more likely to get a match */
if (node->havenullrows &&
findPartialMatch(node->hashnulls, slot))
findPartialMatch(node->hashnulls, slot, node->cur_eq_funcs))
{
ExecClearTuple(slot);
*isNull = true;
return BoolGetDatum(false);
}
if (node->havehashrows &&
findPartialMatch(node->hashtable, slot))
findPartialMatch(node->hashtable, slot, node->cur_eq_funcs))
{
ExecClearTuple(slot);
*isNull = true;
@ -573,9 +574,13 @@ buildSubPlanHash(SubPlanState *node, ExprContext *econtext)
* We have to scan the whole hashtable; we can't usefully use hashkeys
* to guide probing, since we might get partial matches on tuples with
* hashkeys quite unrelated to what we'd get from the given tuple.
*
* Caller must provide the equality functions to use, since in cross-type
* cases these are different from the hashtable's internal functions.
*/
static bool
findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot)
findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot,
FmgrInfo *eqfunctions)
{
int numCols = hashtable->numCols;
AttrNumber *keyColIdx = hashtable->keyColIdx;
@ -588,7 +593,7 @@ findPartialMatch(TupleHashTable hashtable, TupleTableSlot *slot)
ExecStoreMinimalTuple(entry->firstTuple, hashtable->tableslot, false);
if (!execTuplesUnequal(slot, hashtable->tableslot,
numCols, keyColIdx,
hashtable->cur_eq_funcs,
eqfunctions,
hashtable->tempcxt))
{
TermTupleHashIterator(&hashiter);