From d05492e9078f00f1b4585312108f9f2fe0b48976 Mon Sep 17 00:00:00 2001 From: Jeff Davis Date: Tue, 4 Mar 2025 12:46:48 -0800 Subject: [PATCH v8 6/7] Use ExecCopySlotMinimalTupleExtra() to avoid a memcpy. Previously, ExecFetchSlotMinimalTuple() could cause an unnecessary copy for hash-based set operations. Use the new API ExecCopySlotMinimalTupleExtra() to perform the copy while also allocating the extra space needed for the 'additional' data. Discussion: https://postgr.es/m/AApHDvpN4v3t_sdz4dvrv1Fx_ZPw=twSnxuTEytRYP7LFz5K9A@mail.gmail.com Reviewed-by: David Rowley --- src/backend/executor/execGrouping.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c index 5c06cc6da40..255bd795361 100644 --- a/src/backend/executor/execGrouping.c +++ b/src/backend/executor/execGrouping.c @@ -481,21 +481,13 @@ LookupTupleHashEntry_internal(TupleHashTable hashtable, TupleTableSlot *slot, else { /* created new entry */ - bool shouldFree; - char *mem; - MinimalTuple mtup; - *isnew = true; - MemoryContextSwitchTo(hashtable->tempcxt); - - /* ignore shouldFree, because we're in the temp context anyway */ - mtup = ExecFetchSlotMinimalTuple(slot, &shouldFree); + MemoryContextSwitchTo(hashtable->tablecxt); /* - * Allocate enough memory in the tablecxt for the additionalsize - * followed by the tuple. Clear the additional data, and copy the - * tuple. + * Copy the first tuple into the table context, and request + * additionalsize extra bytes before the allocation. * * The caller can get a pointer to the additional data with * TupleHashEntryGetAdditional(), and store arbitrary data there. @@ -503,11 +495,8 @@ LookupTupleHashEntry_internal(TupleHashTable hashtable, TupleTableSlot *slot, * allocation avoids the need to store an extra pointer in * TupleHashEntryData or allocate an additional chunk. */ - mem = MemoryContextAlloc(hashtable->tablecxt, - mtup->t_len + hashtable->additionalsize); - memset(mem, 0, hashtable->additionalsize); - entry->firstTuple = (MinimalTuple) (mem + hashtable->additionalsize); - memcpy(entry->firstTuple, mtup, mtup->t_len); + entry->firstTuple = ExecCopySlotMinimalTupleExtra(slot, + hashtable->additionalsize); } } else -- 2.34.1