Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit45b0f35

Browse files
committed
Avoid leaking memory while evaluating arguments for a table function.
ExecMakeTableFunctionResult evaluated the arguments for a function-in-FROMin the query-lifespan memory context. This is insignificant in simplecases where the function relation is scanned only once; but if the functionis in a sub-SELECT or is on the inside of a nested loop, any memoryconsumed during argument evaluation can add up quickly. (The potential fortrouble here had been foreseen long ago, per existing comments; but we'dnot previously seen a complaint from the field about it.) To fix, createan additional temporary context just for this purpose.Per an example from MauMau. Back-patch to all active branches.
1 parent686f362 commit45b0f35

File tree

4 files changed

+30
-4
lines changed

4 files changed

+30
-4
lines changed

‎src/backend/executor/execQual.c

Lines changed: 11 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -2002,6 +2002,7 @@ ExecMakeFunctionResultNoSets(FuncExprState *fcache,
20022002
Tuplestorestate*
20032003
ExecMakeTableFunctionResult(ExprState*funcexpr,
20042004
ExprContext*econtext,
2005+
MemoryContextargContext,
20052006
TupleDescexpectedDesc,
20062007
boolrandomAccess)
20072008
{
@@ -2083,12 +2084,18 @@ ExecMakeTableFunctionResult(ExprState *funcexpr,
20832084
/*
20842085
* Evaluate the function's argument list.
20852086
*
2086-
* Note: ideally, we'd do this in the per-tuple context, but then the
2087-
* argument values would disappear when we reset the context in the
2088-
* inner loop. So do it in caller context. Perhaps we should make a
2089-
* separate context just to hold the evaluated arguments?
2087+
* We can't do this in the per-tuple context: the argument values
2088+
* would disappear when we reset that context in the inner loop. And
2089+
* the caller's CurrentMemoryContext is typically a query-lifespan
2090+
* context, so we don't want to leak memory there. We require the
2091+
* caller to pass a separate memory context that can be used for this,
2092+
* and can be reset each time through to avoid bloat.
20902093
*/
2094+
MemoryContextReset(argContext);
2095+
oldcontext=MemoryContextSwitchTo(argContext);
20912096
argDone=ExecEvalFuncArgs(&fcinfo,fcache->args,econtext);
2097+
MemoryContextSwitchTo(oldcontext);
2098+
20922099
/* We don't allow sets in the arguments of the table function */
20932100
if (argDone!=ExprSingleResult)
20942101
ereport(ERROR,

‎src/backend/executor/nodeFunctionscan.c

Lines changed: 16 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -28,6 +28,7 @@
2828
#include"nodes/nodeFuncs.h"
2929
#include"parser/parsetree.h"
3030
#include"utils/builtins.h"
31+
#include"utils/memutils.h"
3132

3233

3334
/*
@@ -94,6 +95,7 @@ FunctionNext(FunctionScanState *node)
9495
node->funcstates[0].tstore=tstore=
9596
ExecMakeTableFunctionResult(node->funcstates[0].funcexpr,
9697
node->ss.ps.ps_ExprContext,
98+
node->argcontext,
9799
node->funcstates[0].tupdesc,
98100
node->eflags&EXEC_FLAG_BACKWARD);
99101

@@ -152,6 +154,7 @@ FunctionNext(FunctionScanState *node)
152154
fs->tstore=
153155
ExecMakeTableFunctionResult(fs->funcexpr,
154156
node->ss.ps.ps_ExprContext,
157+
node->argcontext,
155158
fs->tupdesc,
156159
node->eflags&EXEC_FLAG_BACKWARD);
157160

@@ -515,6 +518,19 @@ ExecInitFunctionScan(FunctionScan *node, EState *estate, int eflags)
515518
ExecAssignResultTypeFromTL(&scanstate->ss.ps);
516519
ExecAssignScanProjectionInfo(&scanstate->ss);
517520

521+
/*
522+
* Create a memory context that ExecMakeTableFunctionResult can use to
523+
* evaluate function arguments in. We can't use the per-tuple context for
524+
* this because it gets reset too often; but we don't want to leak
525+
* evaluation results into the query-lifespan context either. We just
526+
* need one context, because we evaluate each function separately.
527+
*/
528+
scanstate->argcontext=AllocSetContextCreate(CurrentMemoryContext,
529+
"Table function arguments",
530+
ALLOCSET_DEFAULT_MINSIZE,
531+
ALLOCSET_DEFAULT_INITSIZE,
532+
ALLOCSET_DEFAULT_MAXSIZE);
533+
518534
returnscanstate;
519535
}
520536

‎src/include/executor/executor.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -231,6 +231,7 @@ extern Datum GetAttributeByName(HeapTupleHeader tuple, const char *attname,
231231
bool*isNull);
232232
externTuplestorestate*ExecMakeTableFunctionResult(ExprState*funcexpr,
233233
ExprContext*econtext,
234+
MemoryContextargContext,
234235
TupleDescexpectedDesc,
235236
boolrandomAccess);
236237
externDatumExecEvalExprSwitchContext(ExprState*expression,ExprContext*econtext,

‎src/include/nodes/execnodes.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1407,6 +1407,7 @@ typedef struct SubqueryScanState
14071407
*nfuncsnumber of functions being executed
14081408
*funcstatesper-function execution states (private in
14091409
*nodeFunctionscan.c)
1410+
*argcontextmemory context to evaluate function arguments in
14101411
* ----------------
14111412
*/
14121413
structFunctionScanPerFuncState;
@@ -1421,6 +1422,7 @@ typedef struct FunctionScanState
14211422
intnfuncs;
14221423
structFunctionScanPerFuncState*funcstates;/* array of length
14231424
* nfuncs */
1425+
MemoryContextargcontext;
14241426
}FunctionScanState;
14251427

14261428
/* ----------------

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp