diff options
author | Jeff Davis | 2025-03-25 05:06:02 +0000 |
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committer | Jeff Davis | 2025-03-25 05:06:02 +0000 |
commit | 626df47ad9db809dc8f93330175ab95b75914721 (patch) | |
tree | db18183d49021a32b56ba0d42517bbb3f7f416c7 | |
parent | a0942f441ed651f6345d969b7a8f4774eda1fceb (diff) |
Remove 'additional' pointer from TupleHashEntryData.
Reduces memory required for hash aggregation by avoiding an allocation
and a pointer in the TupleHashEntryData structure. That structure is
used for all buckets, whether occupied or not, so the savings is
substantial.
Discussion: https://postgr.es/m/AApHDvpN4v3t_sdz4dvrv1Fx_ZPw=twSnxuTEytRYP7LFz5K9A@mail.gmail.com
Reviewed-by: David Rowley <[email protected]>
-rw-r--r-- | src/backend/executor/execGrouping.c | 17 | ||||
-rw-r--r-- | src/include/executor/executor.h | 5 | ||||
-rw-r--r-- | src/include/nodes/execnodes.h | 1 |
3 files changed, 16 insertions, 7 deletions
diff --git a/src/backend/executor/execGrouping.c b/src/backend/executor/execGrouping.c index a9d212aaec6..255bd795361 100644 --- a/src/backend/executor/execGrouping.c +++ b/src/backend/executor/execGrouping.c @@ -485,11 +485,18 @@ LookupTupleHashEntry_internal(TupleHashTable hashtable, TupleTableSlot *slot, MemoryContextSwitchTo(hashtable->tablecxt); - 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 before the allocation. + * + * The caller can get a pointer to the additional data with + * TupleHashEntryGetAdditional(), and store arbitrary data there. + * Placing both the tuple and additional data in the same + * allocation avoids the need to store an extra pointer in + * TupleHashEntryData or allocate an additional chunk. + */ + entry->firstTuple = ExecCopySlotMinimalTupleExtra(slot, + hashtable->additionalsize); } } else diff --git a/src/include/executor/executor.h b/src/include/executor/executor.h index 69396a9d7f8..6a1fec88928 100644 --- a/src/include/executor/executor.h +++ b/src/include/executor/executor.h @@ -188,7 +188,10 @@ TupleHashEntryGetTuple(TupleHashEntry entry) static inline void * TupleHashEntryGetAdditional(TupleHashTable hashtable, TupleHashEntry entry) { - return entry->additional; + if (hashtable->additionalsize > 0) + return (char *) entry->firstTuple - hashtable->additionalsize; + else + return NULL; } #endif diff --git a/src/include/nodes/execnodes.h b/src/include/nodes/execnodes.h index 7df25d7e64f..e42f9f9f957 100644 --- a/src/include/nodes/execnodes.h +++ b/src/include/nodes/execnodes.h @@ -840,7 +840,6 @@ typedef struct TupleHashTableData *TupleHashTable; typedef struct TupleHashEntryData { MinimalTuple firstTuple; /* copy of first tuple in this group */ - void *additional; /* user data */ uint32 status; /* hash status */ uint32 hash; /* hash value (cached) */ } TupleHashEntryData; |