Ignore BRIN indexes when checking for HOT updates

When determining whether an index update may be skipped by using HOT, we
can ignore attributes indexed by block summarizing indexes without
references to individual tuples that need to be cleaned up.

A new type TU_UpdateIndexes provides a signal to the executor to
determine which indexes to update - no indexes, all indexes, or only the
summarizing indexes.

This also removes rd_indexattr list, and replaces it with rd_attrsvalid
flag. The list was not used anywhere, and a simple flag is sufficient.

This was originally committed as 5753d4e, but then got reverted by
e3fcca0 because of correctness issues.

Original patch by Josef Simanek, various fixes and improvements by Tomas
Vondra and me.

Authors: Matthias van de Meent, Josef Simanek, Tomas Vondra
Reviewed-by: Tomas Vondra, Alvaro Herrera
Discussion: https://postgr.es/m/[email protected]
Discussion: https://postgr.es/m/CAFp7QwpMRGcDAQumN7onN9HjrJ3u4X3ZRXdGFT0K5G2JWvnbWg%40mail.gmail.com

Author: tvondra

doc/src/sgml/indexam.sgml

@@ -127,6 +127,9 @@ typedef struct IndexAmRoutine
     bool        amcaninclude;
     /* does AM use maintenance_work_mem? */
     bool        amusemaintenanceworkmem;
+    /* does AM summarize tuples, with at least all tuples in the block
+     * summarized in one summary */
+    bool        amsummarizing;
     /* OR of parallel vacuum flags */
     uint8       amparallelvacuumoptions;
     /* type of data stored in index, or InvalidOid if variable */
@@ -247,6 +250,16 @@ typedef struct IndexAmRoutine
    null, independently of <structfield>amoptionalkey</structfield>.
   </para>
 
+  <para>
+   The <structfield>amsummarizing</structfield> flag indicates whether the
+   access method summarizes the indexed tuples, with summarizing granularity
+   of at least per block.
+   Access methods that do not point to individual tuples, but to block ranges
+   (like <acronym>BRIN</acronym>), may allow the <acronym>HOT</acronym> optimization
+   to continue. This does not apply to attributes referenced in index
+   predicates, an update of such attribute always disables <acronym>HOT</acronym>.
+  </para>
+
  </sect1>
 
  <sect1 id="index-functions">

src/backend/access/brin/brin.c

@@ -109,6 +109,7 @@ brinhandler(PG_FUNCTION_ARGS)
 	amroutine->amcanparallel = false;
 	amroutine->amcaninclude = false;
 	amroutine->amusemaintenanceworkmem = false;
+	amroutine->amsummarizing = true;
 	amroutine->amparallelvacuumoptions =
 		VACUUM_OPTION_PARALLEL_CLEANUP;
 	amroutine->amkeytype = InvalidOid;

src/backend/access/gin/ginutil.c

@@ -56,6 +56,7 @@ ginhandler(PG_FUNCTION_ARGS)
 	amroutine->amcanparallel = false;
 	amroutine->amcaninclude = false;
 	amroutine->amusemaintenanceworkmem = true;
+	amroutine->amsummarizing = false;
 	amroutine->amparallelvacuumoptions =
 		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_CLEANUP;
 	amroutine->amkeytype = InvalidOid;

src/backend/access/gist/gist.c

@@ -78,6 +78,7 @@ gisthandler(PG_FUNCTION_ARGS)
 	amroutine->amcanparallel = false;
 	amroutine->amcaninclude = true;
 	amroutine->amusemaintenanceworkmem = false;
+	amroutine->amsummarizing = false;
 	amroutine->amparallelvacuumoptions =
 		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
 	amroutine->amkeytype = InvalidOid;

src/backend/access/hash/hash.c

@@ -75,6 +75,7 @@ hashhandler(PG_FUNCTION_ARGS)
 	amroutine->amcanparallel = false;
 	amroutine->amcaninclude = false;
 	amroutine->amusemaintenanceworkmem = false;
+	amroutine->amsummarizing = false;
 	amroutine->amparallelvacuumoptions =
 		VACUUM_OPTION_PARALLEL_BULKDEL;
 	amroutine->amkeytype = INT4OID;

src/backend/access/heap/heapam.c

@@ -2924,11 +2924,13 @@ simple_heap_delete(Relation relation, ItemPointer tid)
 TM_Result
 heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 			CommandId cid, Snapshot crosscheck, bool wait,
-			TM_FailureData *tmfd, LockTupleMode *lockmode)
+			TM_FailureData *tmfd, LockTupleMode *lockmode,
+			TU_UpdateIndexes *update_indexes)
 {
 	TM_Result	result;
 	TransactionId xid = GetCurrentTransactionId();
 	Bitmapset  *hot_attrs;
+	Bitmapset  *sum_attrs;
 	Bitmapset  *key_attrs;
 	Bitmapset  *id_attrs;
 	Bitmapset  *interesting_attrs;
@@ -2951,6 +2953,7 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 	bool		have_tuple_lock = false;
 	bool		iscombo;
 	bool		use_hot_update = false;
+	bool		summarized_update = false;
 	bool		key_intact;
 	bool		all_visible_cleared = false;
 	bool		all_visible_cleared_new = false;
@@ -2996,12 +2999,16 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 	 * Note that we get copies of each bitmap, so we need not worry about
 	 * relcache flush happening midway through.
 	 */
-	hot_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_ALL);
+	hot_attrs = RelationGetIndexAttrBitmap(relation,
+										   INDEX_ATTR_BITMAP_HOT_BLOCKING);
+	sum_attrs = RelationGetIndexAttrBitmap(relation,
+										   INDEX_ATTR_BITMAP_SUMMARIZED);
 	key_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_KEY);
 	id_attrs = RelationGetIndexAttrBitmap(relation,
 										  INDEX_ATTR_BITMAP_IDENTITY_KEY);
 	interesting_attrs = NULL;
 	interesting_attrs = bms_add_members(interesting_attrs, hot_attrs);
+	interesting_attrs = bms_add_members(interesting_attrs, sum_attrs);
 	interesting_attrs = bms_add_members(interesting_attrs, key_attrs);
 	interesting_attrs = bms_add_members(interesting_attrs, id_attrs);
 
@@ -3311,7 +3318,10 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 			UnlockTupleTuplock(relation, &(oldtup.t_self), *lockmode);
 		if (vmbuffer != InvalidBuffer)
 			ReleaseBuffer(vmbuffer);
+		*update_indexes = TU_None;
+
 		bms_free(hot_attrs);
+		bms_free(sum_attrs);
 		bms_free(key_attrs);
 		bms_free(id_attrs);
 		bms_free(modified_attrs);
@@ -3633,7 +3643,19 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 		 * changed.
 		 */
 		if (!bms_overlap(modified_attrs, hot_attrs))
+		{
 			use_hot_update = true;
+
+			/*
+			 * If none of the columns that are used in hot-blocking indexes
+			 * were updated, we can apply HOT, but we do still need to check
+			 * if we need to update the summarizing indexes, and update those
+			 * indexes if the columns were updated, or we may fail to detect
+			 * e.g. value bound changes in BRIN minmax indexes.
+			 */
+			if (bms_overlap(modified_attrs, sum_attrs))
+				summarized_update = true;
+		}
 	}
 	else
 	{
@@ -3793,10 +3815,27 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 		heap_freetuple(heaptup);
 	}
 
+	/*
+	 * If it is a HOT update, the update may still need to update summarized
+	 * indexes, lest we fail to update those summaries and get incorrect
+	 * results (for example, minmax bounds of the block may change with this
+	 * update).
+	 */
+	if (use_hot_update)
+	{
+		if (summarized_update)
+			*update_indexes = TU_Summarizing;
+		else
+			*update_indexes = TU_None;
+	}
+	else
+		*update_indexes = TU_All;
+
 	if (old_key_tuple != NULL && old_key_copied)
 		heap_freetuple(old_key_tuple);
 
 	bms_free(hot_attrs);
+	bms_free(sum_attrs);
 	bms_free(key_attrs);
 	bms_free(id_attrs);
 	bms_free(modified_attrs);
@@ -3951,7 +3990,8 @@ HeapDetermineColumnsInfo(Relation relation,
  * via ereport().
  */
 void
-simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup)
+simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup,
+				   TU_UpdateIndexes *update_indexes)
 {
 	TM_Result	result;
 	TM_FailureData tmfd;
@@ -3960,7 +4000,7 @@ simple_heap_update(Relation relation, ItemPointer otid, HeapTuple tup)
 	result = heap_update(relation, otid, tup,
 						 GetCurrentCommandId(true), InvalidSnapshot,
 						 true /* wait for commit */ ,
-						 &tmfd, &lockmode);
+						 &tmfd, &lockmode, update_indexes);
 	switch (result)
 	{
 		case TM_SelfModified:

src/backend/access/heap/heapam_handler.c

@@ -314,7 +314,7 @@ static TM_Result
 heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot,
 					CommandId cid, Snapshot snapshot, Snapshot crosscheck,
 					bool wait, TM_FailureData *tmfd,
-					LockTupleMode *lockmode, bool *update_indexes)
+					LockTupleMode *lockmode, TU_UpdateIndexes *update_indexes)
 {
 	bool		shouldFree = true;
 	HeapTuple	tuple = ExecFetchSlotHeapTuple(slot, true, &shouldFree);
@@ -325,7 +325,7 @@ heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot,
 	tuple->t_tableOid = slot->tts_tableOid;
 
 	result = heap_update(relation, otid, tuple, cid, crosscheck, wait,
-						 tmfd, lockmode);
+						 tmfd, lockmode, update_indexes);
 	ItemPointerCopy(&tuple->t_self, &slot->tts_tid);
 
 	/*
@@ -334,9 +334,20 @@ heapam_tuple_update(Relation relation, ItemPointer otid, TupleTableSlot *slot,
 	 * Note: heap_update returns the tid (location) of the new tuple in the
 	 * t_self field.
 	 *
-	 * If it's a HOT update, we mustn't insert new index entries.
+	 * If the update is not HOT, we must update all indexes. If the update
+	 * is HOT, it could be that we updated summarized columns, so we either
+	 * update only summarized indexes, or none at all.
 	 */
-	*update_indexes = result == TM_Ok && !HeapTupleIsHeapOnly(tuple);
+	if (result != TM_Ok)
+	{
+		Assert(*update_indexes == TU_None);
+		*update_indexes = TU_None;
+	}
+	else if (!HeapTupleIsHeapOnly(tuple))
+		Assert(*update_indexes == TU_All);
+	else
+		Assert((*update_indexes == TU_Summarizing) ||
+			   (*update_indexes == TU_None));
 
 	if (shouldFree)
 		pfree(tuple);

src/backend/access/nbtree/nbtree.c

@@ -114,6 +114,7 @@ bthandler(PG_FUNCTION_ARGS)
 	amroutine->amcanparallel = true;
 	amroutine->amcaninclude = true;
 	amroutine->amusemaintenanceworkmem = false;
+	amroutine->amsummarizing = false;
 	amroutine->amparallelvacuumoptions =
 		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
 	amroutine->amkeytype = InvalidOid;

src/backend/access/spgist/spgutils.c

@@ -62,6 +62,7 @@ spghandler(PG_FUNCTION_ARGS)
 	amroutine->amcanparallel = false;
 	amroutine->amcaninclude = true;
 	amroutine->amusemaintenanceworkmem = false;
+	amroutine->amsummarizing = false;
 	amroutine->amparallelvacuumoptions =
 		VACUUM_OPTION_PARALLEL_BULKDEL | VACUUM_OPTION_PARALLEL_COND_CLEANUP;
 	amroutine->amkeytype = InvalidOid;

src/backend/access/table/tableam.c

@@ -345,7 +345,7 @@ void
 simple_table_tuple_update(Relation rel, ItemPointer otid,
 						  TupleTableSlot *slot,
 						  Snapshot snapshot,
-						  bool *update_indexes)
+						  TU_UpdateIndexes *update_indexes)
 {
 	TM_Result	result;
 	TM_FailureData tmfd;