diff options
author | Tom Lane | 2014-06-20 02:13:54 +0000 |
---|---|---|
committer | Tom Lane | 2014-06-20 02:13:54 +0000 |
commit | 06d5eacbc0a7db22422fc07aca56f6e69b02b8ea (patch) | |
tree | 0d6d998e20320bb072e1cd36755c074010cb0344 | |
parent | 94ab763278459ef8f279bdf98bcda9a73accad7e (diff) |
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.
-rw-r--r-- | src/backend/executor/execQual.c | 15 | ||||
-rw-r--r-- | src/backend/executor/nodeFunctionscan.c | 15 | ||||
-rw-r--r-- | src/include/executor/executor.h | 1 | ||||
-rw-r--r-- | src/include/nodes/execnodes.h | 2 |
4 files changed, 29 insertions, 4 deletions
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c index bf86e7ae33e..2fb10c716d7 100644 --- a/src/backend/executor/execQual.c +++ b/src/backend/executor/execQual.c @@ -1981,6 +1981,7 @@ ExecMakeFunctionResultNoSets(FuncExprState *fcache, Tuplestorestate * ExecMakeTableFunctionResult(ExprState *funcexpr, ExprContext *econtext, + MemoryContext argContext, TupleDesc expectedDesc, bool randomAccess) { @@ -2062,12 +2063,18 @@ 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, diff --git a/src/backend/executor/nodeFunctionscan.c b/src/backend/executor/nodeFunctionscan.c index 42d699d0159..98ecd02a20e 100644 --- a/src/backend/executor/nodeFunctionscan.c +++ b/src/backend/executor/nodeFunctionscan.c @@ -26,6 +26,7 @@ #include "funcapi.h" #include "nodes/nodeFuncs.h" #include "utils/builtins.h" +#include "utils/memutils.h" static TupleTableSlot *FunctionNext(FunctionScanState *node); @@ -65,6 +66,7 @@ FunctionNext(FunctionScanState *node) node->tuplestorestate = tuplestorestate = ExecMakeTableFunctionResult(node->funcexpr, node->ss.ps.ps_ExprContext, + node->argcontext, node->tupdesc, node->eflags & EXEC_FLAG_BACKWARD); } @@ -228,6 +230,19 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags) ExecAssignResultTypeFromTL(&scanstate->ss.ps); ExecAssignScanProjectionInfo(&scanstate->ss); + /* + * Create a memory context that ExecMakeTableFunctionResult can use to + * evaluate function arguments in. We can't use the per-tuple context for + * this because it gets reset too often; but we don't want to leak + * evaluation results into the query-lifespan context either. We just + * need one context, because we evaluate each function separately. + */ + scanstate->argcontext = AllocSetContextCreate(CurrentMemoryContext, + "Table function arguments", + ALLOCSET_DEFAULT_MINSIZE, + ALLOCSET_DEFAULT_INITSIZE, + ALLOCSET_DEFAULT_MAXSIZE); + return scanstate; } diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index b834282287d..2eb9b1f2538 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -223,6 +223,7 @@ extern Datum GetAttributeByName(HeapTupleHeader tuple, const char *attname, bool *isNull); extern Tuplestorestate *ExecMakeTableFunctionResult(ExprState *funcexpr, ExprContext *econtext, + MemoryContext argContext, TupleDesc expectedDesc, bool randomAccess); extern Datum ExecEvalExprSwitchContext(ExprState *expression, ExprContext *econtext, diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index c16f6404710..10f18b0ebd0 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -1353,6 +1353,7 @@ typedef struct SubqueryScanState * tupdesc expected return tuple description * tuplestorestate private state of tuplestore.c * funcexpr state for function expression being evaluated + * argcontext memory context to evaluate function arguments in * ---------------- */ typedef struct FunctionScanState @@ -1362,6 +1363,7 @@ typedef struct FunctionScanState TupleDesc tupdesc; Tuplestorestate *tuplestorestate; ExprState *funcexpr; + MemoryContext argcontext; } FunctionScanState; /* ---------------- |