Please see the updated patch, do you mean something like this? (there might be a simpler way for doing this)
Best,
Talha.
From: Andres Freund <andres@anarazel.de> Sent: Wednesday, March 31, 2021 10:49 PM To: Sait Talha Nisanci <Sait.Nisanci@microsoft.com> Cc: pgsql-hackers <pgsql-hackers@postgresql.org>; Metin Doslu <Metin.Doslu@microsoft.com> Subject: [EXTERNAL] Re: Crash in record_type_typmod_compare
Hi,
On 2021-03-31 13:26:34 +0000, Sait Talha Nisanci wrote: > diff --git a/src/backend/utils/cache/typcache.c b/src/backend/utils/cache/typcache.c > index 4915ef5934..4757e8fa80 100644 > --- a/src/backend/utils/cache/typcache.c > +++ b/src/backend/utils/cache/typcache.c > @@ -1970,18 +1970,16 @@ assign_record_type_typmod(TupleDesc tupDesc) > CreateCacheMemoryContext(); > } > > - /* Find or create a hashtable entry for this tuple descriptor */ > + /* Find a hashtable entry for this tuple descriptor */ > recentry = (RecordCacheEntry *) hash_search(RecordCacheHash, > (void *) &tupDesc, > - HASH_ENTER, &found); > + HASH_FIND, &found); > if (found && recentry->tupdesc != NULL) > { > tupDesc->tdtypmod = recentry->tupdesc->tdtypmod; > return; > } > > - /* Not present, so need to manufacture an entry */ > - recentry->tupdesc = NULL; > oldcxt = MemoryContextSwitchTo(CacheMemoryContext); > > /* Look in the SharedRecordTypmodRegistry, if attached */ > @@ -1995,6 +1993,10 @@ assign_record_type_typmod(TupleDesc tupDesc) > } > ensure_record_cache_typmod_slot_exists(entDesc->tdtypmod); > RecordCacheArray[entDesc->tdtypmod] = entDesc; > + /* Not present, so need to manufacture an entry */ > + recentry = (RecordCacheEntry *) hash_search(RecordCacheHash, > + (void *) &tupDesc, > + HASH_ENTER, NULL); > recentry->tupdesc = entDesc;
ISTM that the ensure_record_cache_typmod_slot_exists() should be moved to before find_or_make_matching_shared_tupledesc / CreateTupleDescCopy. Otherwise we can leak if the CreateTupleDescCopy() succeeds but ensure_record_cache_typmod_slot_exists() fails. Conversely, if ensure_record_cache_typmod_slot_exists() succeeds, but CreateTupleDescCopy() we won't leak, since the former is just repalloc()ing allocations.
