8000 Use a separate memory context for GIN scan keys. · mitin001/postgres@d88976c · GitHub
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hlinnakahlinnaka
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Use a separate memory context for GIN scan keys.
It was getting tedious to track and release all the different things that form a scan key. We were leaking at least the queryCategories array, and possibly more, on a rescan. That was visible if a GIN index was used in a nested loop join. This also protects from leaks in extractQuery method. No backpatching, given the lack of complaints from the field. Maybe later, after this has received more field testing.
1 parent 57fe246 commit d88976c

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3 files changed

+29
-21
lines changed

3 files changed

+29
-21
lines changed

‎src/backend/access/gin/ginget.c 8000

Lines changed: 4 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -497,7 +497,7 @@ startScanKey(GinState *ginstate, GinScanOpaque so, GinScanKey key)
497497
}
498498
/* i is now the last required entry. */
499499

500-
MemoryContextSwitchTo(oldCtx);
500+
MemoryContextSwitchTo(so->keyCtx);
501501

502502
key->nrequired = i + 1;
503503
key->nadditional = key->nentries - key->nrequired;
@@ -515,11 +515,14 @@ startScanKey(GinState *ginstate, GinScanOpaque so, GinScanKey key)
515515
}
516516
else
517517
{
518+
MemoryContextSwitchTo(so->keyCtx);
519+
518520
key->nrequired = 1;
519521
key->nadditional = 0;
520522
key->requiredEntries = palloc(1 * sizeof(GinScanEntry));
521523
key->requiredEntries[0] = key->scanEntry[0];
522524
}
525+
MemoryContextSwitchTo(oldCtx);
523526
}
524527

525528
static void

‎src/backend/access/gin/ginscan.c

Lines changed: 23 additions & 20 deletions
Original file line numberDiff line numberDiff line change
@@ -44,6 +44,11 @@ ginbeginscan(PG_FUNCTION_ARGS)
4444
ALLOCSET_DEFAULT_MINSIZE,
4545
ALLOCSET_DEFAULT_INITSIZE,
4646
ALLOCSET_DEFAULT_MAXSIZE);
47+
so->keyCtx = AllocSetContextCreate(CurrentMemoryContext,
48+
"Gin scan key context",
49+
ALLOCSET_DEFAULT_MINSIZE,
50+
ALLOCSET_DEFAULT_INITSIZE,
51+
ALLOCSET_DEFAULT_MAXSIZE);
4752
initGinState(&so->ginstate, scan->indexRelation);
4853

4954
scan->opaque = so;
@@ -227,6 +232,9 @@ ginFillScanKey(GinScanOpaque so, OffsetNumber attnum,
227232
}
228233
}
229234

235+
/*
236+
* Release current scan keys, if any.
237+
*/
230238
void
231239
ginFreeScanKeys(GinScanOpaque so)
232240
{
@@ -235,38 +243,22 @@ ginFreeScanKeys(GinScanOpaque so)
235243
if (so->keys == NULL)
236244
return;
237245

238-
for (i = 0; i < so->nkeys; i++)
239-
{
240-
GinScanKey key = so->keys + i;
241-
242-
pfree(key->scanEntry);
243-
pfree(key->entryRes);
244-
if (key->requiredEntries)
245-
pfree(key->requiredEntries);
246-
if (key->additionalEntries)
247-
pfree(key->additionalEntries);
248-
}
249-
250-
pfree(so->keys);
251-
so->keys = NULL;
252-
so->nkeys = 0;
253-
254246
for (i = 0; i < so->totalentries; i++)
255247
{
256248
GinScanEntry entry = so->entries[i];
257249

258250
if (entry->buffer != InvalidBuffer)
259251
ReleaseBuffer(entry->buffer);
260-
if (entry->list)
261-
pfree(entry->list);
262252
if (entry->matchIterator)
263253
tbm_end_iterate(entry->matchIterator);
264254
if (entry->matchBitmap)
265255
tbm_free(entry->matchBitmap);
266-
pfree(entry);
267256
}
268257

269-
pfree(so->entries);
258+
MemoryContextResetAndDeleteChildren(so->keyCtx);
259+
260+
so->keys = NULL;
261+
so->nkeys = 0;
270262
so->entries = NULL;
271263
so->totalentries = 0;
272264
}
@@ -278,6 +270,14 @@ ginNewScanKey(IndexScanDesc scan)
278270
GinScanOpaque so = (GinScanOpaque) scan->opaque;
279271
int i;
280272
bool hasNullQuery = false;
273+
MemoryContext oldCtx;
274+
275+
/*
276+
* Allocate all the scan key information in the key context. (If
277+
* extractQuery leaks anything there, it won't be reset until the end of
278+
* scan or rescan, but that's OK.)
279+
*/
280+
oldCtx = MemoryContextSwitchTo(so->keyCtx);
281281

282282
/* if no scan keys provided, allocate extra EVERYTHING GinScanKey */
283283
so->keys = (GinScanKey)
@@ -412,6 +412,8 @@ ginNewScanKey(IndexScanDesc scan)
412412
RelationGetRelationName(scan->indexRelation))));
413413
}
414414

415+
MemoryContextSwitchTo(oldCtx);
416+
415417
pgstat_count_index_scan(scan->indexRelation);
416418
}
417419

@@ -445,6 +447,7 @@ ginendscan(PG_FUNCTION_ARGS)
445447
ginFreeScanKeys(so);
446448

447449
MemoryContextDelete(so->tempCtx);
450+
MemoryContextDelete(so->keyCtx);
448451

449452
pfree(so);
450453

‎src/include/access/gin_private.h

Lines changed: 2 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -888,6 +888,8 @@ typedef struct GinScanOpaqueData
888888
uint32 totalentries;
889889
uint32 allocentries; /* allocated length of entries[] */
890890

891+
MemoryContext keyCtx; /* used to hold key and entry data */
892+
891893
bool isVoidRes; /* true if query is unsatisfiable */
892894
} GinScanOpaqueData;
893895

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