TupleHashTable: store additional data along with tuple.

Previously, the caller needed to allocate the memory and the
TupleHashTable would store a pointer to it. That wastes space for the
palloc overhead as well as the size of the pointer itself.

Now, the TupleHashTable relies on the caller to correctly specify the
additionalsize, and allocates that amount of space. The caller can
then request a pointer into that space.

Discussion: https://postgr.es/m/b9cbf0219a9859dc8d240311643ff4362fd9602c.camel@j-davis.com
Reviewed-by: Heikki Linnakangas

1 files changed, 8 insertions, 12 deletions

diff --git a/src/backend/executor/nodeAgg.c b/src/backend/executor/nodeAgg.c
index 3005b5c0e3b..19640752967 100644
--- a/src/backend/executor/nodeAgg.c
+++ b/src/backend/executor/nodeAgg.c
@@ -1713,7 +1713,7 @@ hash_agg_entry_size(int numTrans, Size tupleWidth, Size transitionSpace)
 		transitionChunkSize = 0;
 
 	return
-		sizeof(TupleHashEntryData) +
+		TupleHashEntrySize() +
 		tupleChunkSize +
 		pergroupChunkSize +
 		transitionChunkSize;
@@ -1954,7 +1954,7 @@ hash_agg_update_metrics(AggState *aggstate, bool from_tape, int npartitions)
 	if (aggstate->hash_ngroups_current > 0)
 	{
 		aggstate->hashentrysize =
-			sizeof(TupleHashEntryData) +
+			TupleHashEntrySize() +
 			(hashkey_mem / (double) aggstate->hash_ngroups_current);
 	}
 }
@@ -2055,11 +2055,7 @@ initialize_hash_entry(AggState *aggstate, TupleHashTable hashtable,
 	if (aggstate->numtrans == 0)
 		return;
 
-	pergroup = (AggStatePerGroup)
-		MemoryContextAlloc(hashtable->tablecxt,
-						   sizeof(AggStatePerGroupData) * aggstate->numtrans);
-
-	entry->additional = pergroup;
+	pergroup = (AggStatePerGroup) TupleHashEntryGetAdditional(entry);
 
 	/*
 	 * Initialize aggregates for new tuple group, lookup_hash_entries()
@@ -2123,7 +2119,7 @@ lookup_hash_entries(AggState *aggstate)
 		{
 			if (isnew)
 				initialize_hash_entry(aggstate, hashtable, entry);
-			pergroup[setno] = entry->additional;
+			pergroup[setno] = TupleHashEntryGetAdditional(entry);
 		}
 		else
 		{
@@ -2681,7 +2677,7 @@ agg_refill_hash_table(AggState *aggstate)
 		{
 			if (isnew)
 				initialize_hash_entry(aggstate, perhash->hashtable, entry);
-			aggstate->hash_pergroup[batch->setno] = entry->additional;
+			aggstate->hash_pergroup[batch->setno] = TupleHashEntryGetAdditional(entry);
 			advance_aggregates(aggstate);
 		}
 		else
@@ -2773,7 +2769,7 @@ agg_retrieve_hash_table_in_memory(AggState *aggstate)
 	ExprContext *econtext;
 	AggStatePerAgg peragg;
 	AggStatePerGroup pergroup;
-	TupleHashEntryData *entry;
+	TupleHashEntry entry;
 	TupleTableSlot *firstSlot;
 	TupleTableSlot *result;
 	AggStatePerHash perhash;
@@ -2845,7 +2841,7 @@ agg_retrieve_hash_table_in_memory(AggState *aggstate)
 		 * Transform representative tuple back into one with the right
 		 * columns.
 		 */
-		ExecStoreMinimalTuple(entry->firstTuple, hashslot, false);
+		ExecStoreMinimalTuple(TupleHashEntryGetTuple(entry), hashslot, false);
 		slot_getallattrs(hashslot);
 
 		ExecClearTuple(firstSlot);
@@ -2861,7 +2857,7 @@ agg_retrieve_hash_table_in_memory(AggState *aggstate)
 		}
 		ExecStoreVirtualTuple(firstSlot);
 
-		pergroup = (AggStatePerGroup) entry->additional;
+		pergroup = (AggStatePerGroup) TupleHashEntryGetAdditional(entry);
 
 		/*
 		 * Use the representative input tuple for any references to