From 449563fcdbaad76fa0841cdb82ce4e4f55d75163 Mon Sep 17 00:00:00 2001 From: Jeff Davis Date: Tue, 14 Jan 2025 16:17:00 -0800 Subject: [PATCH v6 3/7] Store additional data after mintuple --- src/backend/executor/execGrouping.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c index 6763c35457c..90833216e3b 100644 --- a/src/backend/executor/execGrouping.c +++ b/src/backend/executor/execGrouping.c @@ -23,7 +23,6 @@ struct TupleHashEntryData { MinimalTuple firstTuple; /* copy of first tuple in this group */ - void *additional; /* user data */ uint32 status; /* hash status */ uint32 hash; /* hash value (cached) */ }; @@ -302,15 +301,16 @@ TupleHashEntryGetTuple(TupleHashEntry entry) /* * Get a pointer into the additional space allocated for this entry. The - * amount of space available is the additionalsize specified to - * BuildTupleHashTable(). If additionalsize was specified as zero, no + * memory will be maxaligned and zeroed. + * + * The amount of space available is the additionalsize requested in the call + * to BuildTupleHashTable(). If additionalsize was specified as zero, no * additional space is available and this function should not be called. */ void * TupleHashEntryGetAdditional(TupleHashEntry entry) { - Assert(entry->additional != NULL); - return entry->additional; + return (char *) entry->firstTuple + MAXALIGN(entry->firstTuple->t_len); } /* @@ -522,13 +522,17 @@ LookupTupleHashEntry_internal(TupleHashTable hashtable, TupleTableSlot *slot, MemoryContextSwitchTo(hashtable->tablecxt); - /* Copy the first tuple into the table context */ - entry->firstTuple = ExecCopySlotMinimalTuple(slot); - - if (hashtable->additionalsize > 0) - entry->additional = palloc0(hashtable->additionalsize); - else - entry->additional = NULL; + /* + * Copy the first tuple into the table context, and request + * additionalsize extra bytes at the end of the allocation. + * + * The caller can get a pointer to this data with + * TupleHashEntryGetAdditional(), and store arbitrary data there. + * This avoids the need to store an extra pointer or allocate an + * additional chunk, which would waste memory. + */ + entry->firstTuple = ExecCopySlotMinimalTupleExtra(slot, + hashtable->additionalsize); } } else -- 2.34.1