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authorTom Lane <tgl@sss.pgh.pa.us>2014-06-19 22:13:47 -0400
committerTom Lane <tgl@sss.pgh.pa.us>2014-06-19 22:13:47 -0400
commitc1f8fb9bfb0d2a89f646b3186a004d6e4ebdecb4 (patch)
tree39427db4b959016ea25b7d9afb0f4b8813cfc0a1 /src/backend/executor/execQual.c
parent1442b426e5d724c90070f890fed36332f4b17884 (diff)
downloadpostgresql-c1f8fb9bfb0d2a89f646b3186a004d6e4ebdecb4.tar.gz
postgresql-c1f8fb9bfb0d2a89f646b3186a004d6e4ebdecb4.zip
Avoid leaking memory while evaluating arguments for a table function.
ExecMakeTableFunctionResult evaluated the arguments for a function-in-FROM in the query-lifespan memory context. This is insignificant in simple cases where the function relation is scanned only once; but if the function is in a sub-SELECT or is on the inside of a nested loop, any memory consumed during argument evaluation can add up quickly. (The potential for trouble here had been foreseen long ago, per existing comments; but we'd not previously seen a complaint from the field about it.) To fix, create an additional temporary context just for this purpose. Per an example from MauMau. Back-patch to all active branches.
Diffstat (limited to 'src/backend/executor/execQual.c')
-rw-r--r--src/backend/executor/execQual.c15
1 files changed, 11 insertions, 4 deletions
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c
index ab05ec226ea..c6f31a0ad0b 100644
--- a/src/backend/executor/execQual.c
+++ b/src/backend/executor/execQual.c
@@ -2002,6 +2002,7 @@ ExecMakeFunctionResultNoSets(FuncExprState *fcache,
Tuplestorestate *
ExecMakeTableFunctionResult(ExprState *funcexpr,
ExprContext *econtext,
+ MemoryContext argContext,
TupleDesc expectedDesc,
bool randomAccess)
{
@@ -2083,12 +2084,18 @@ ExecMakeTableFunctionResult(ExprState *funcexpr,
/*
* Evaluate the function's argument list.
*
- * Note: ideally, we'd do this in the per-tuple context, but then the
- * argument values would disappear when we reset the context in the
- * inner loop. So do it in caller context. Perhaps we should make a
- * separate context just to hold the evaluated arguments?
+ * We can't do this in the per-tuple context: the argument values
+ * would disappear when we reset that context in the inner loop. And
+ * the caller's CurrentMemoryContext is typically a query-lifespan
+ * context, so we don't want to leak memory there. We require the
+ * caller to pass a separate memory context that can be used for this,
+ * and can be reset each time through to avoid bloat.
*/
+ MemoryContextReset(argContext);
+ oldcontext = MemoryContextSwitchTo(argContext);
argDone = ExecEvalFuncArgs(&fcinfo, fcache->args, econtext);
+ MemoryContextSwitchTo(oldcontext);
+
/* We don't allow sets in the arguments of the table function */
if (argDone != ExprSingleResult)
ereport(ERROR,