Allow index AMs to cache data across aminsert calls within a SQL command.

It's always been possible for index AMs to cache data across successive
amgettuple calls within a single SQL command: the IndexScanDesc.opaque
field is meant for precisely that.  However, no comparable facility
exists for amortizing setup work across successive aminsert calls.
This patch adds such a feature and teaches GIN, GIST, and BRIN to use it
to amortize catalog lookups they'd previously been doing on every call.
(The other standard index AMs keep everything they need in the relcache,
so there's little to improve there.)

For GIN, the overall improvement in a statement that inserts many rows
can be as much as 10%, though it seems a bit less for the other two.
In addition, this makes a really significant difference in runtime
for CLOBBER_CACHE_ALWAYS tests, since in those builds the repeated
catalog lookups are vastly more expensive.

The reason this has been hard up to now is that the aminsert function is
not passed any useful place to cache per-statement data.  What I chose to
do is to add suitable fields to struct IndexInfo and pass that to aminsert.
That's not widening the index AM API very much because IndexInfo is already
within the ken of ambuild; in fact, by passing the same info to aminsert
as to ambuild, this is really removing an inconsistency in the AM API.

Discussion: https://postgr.es/m/27568.1486508680@sss.pgh.pa.us

contrib/bloom/blinsert.c

@@ -190,7 +190,9 @@ blbuildempty(Relation index)
  */
 bool
 blinsert(Relation index, Datum *values, bool *isnull,
-		 ItemPointer ht_ctid, Relation heapRel, IndexUniqueCheck checkUnique)
+		 ItemPointer ht_ctid, Relation heapRel,
+		 IndexUniqueCheck checkUnique,
+		 IndexInfo *indexInfo)
 {
 	BloomState	blstate;
 	BloomTuple *itup;

contrib/bloom/bloom.h

@@ -189,7 +189,8 @@ extern bool blvalidate(Oid opclassoid);
 /* index access method interface functions */
 extern bool blinsert(Relation index, Datum *values, bool *isnull,
 		 ItemPointer ht_ctid, Relation heapRel,
-		 IndexUniqueCheck checkUnique);
+		 IndexUniqueCheck checkUnique,
+		 struct IndexInfo *indexInfo);
 extern IndexScanDesc blbeginscan(Relation r, int nkeys, int norderbys);
 extern int64 blgetbitmap(IndexScanDesc scan, TIDBitmap *tbm);
 extern void blrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,

doc/src/sgml/indexam.sgml

@@ -259,7 +259,8 @@ aminsert (Relation indexRelation,
           bool *isnull,
           ItemPointer heap_tid,
           Relation heapRelation,
-          IndexUniqueCheck checkUnique);
+          IndexUniqueCheck checkUnique,
+          IndexInfo *indexInfo);
 </programlisting>
    Insert a new tuple into an existing index.  The <literal>values</> and
    <literal>isnull</> arrays give the key values to be indexed, and
@@ -287,6 +288,14 @@ aminsert (Relation indexRelation,
    indexed, <function>aminsert</> should just return without doing anything.
   </para>
 
+  <para>
+   If the index AM wishes to cache data across successive index insertions
+   within a SQL statement, it can allocate space
+   in <literal>indexInfo-&gt;ii_Context</literal> and store a pointer to the
+   data in <literal>indexInfo-&gt;ii_AmCache</literal> (which will be NULL
+   initially).
+  </para>
+
   <para>
 <programlisting>
 IndexBulkDeleteResult *

src/backend/access/brin/brin.c

@@ -131,14 +131,15 @@ brinhandler(PG_FUNCTION_ARGS)
 bool
 brininsert(Relation idxRel, Datum *values, bool *nulls,
 		   ItemPointer heaptid, Relation heapRel,
-		   IndexUniqueCheck checkUnique)
+		   IndexUniqueCheck checkUnique,
+		   IndexInfo *indexInfo)
 {
 	BlockNumber pagesPerRange;
-	BrinDesc   *bdesc = NULL;
+	BrinDesc   *bdesc = (BrinDesc *) indexInfo->ii_AmCache;
 	BrinRevmap *revmap;
 	Buffer		buf = InvalidBuffer;
 	MemoryContext tupcxt = NULL;
-	MemoryContext oldcxt = NULL;
+	MemoryContext oldcxt = CurrentMemoryContext;
 
 	revmap = brinRevmapInitialize(idxRel, &pagesPerRange, NULL);
 
@@ -163,14 +164,21 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
 		if (!brtup)
 			break;
 
-		/* First time through? */
+		/* First time through in this statement? */
 		if (bdesc == NULL)
 		{
+			MemoryContextSwitchTo(indexInfo->ii_Context);
 			bdesc = brin_build_desc(idxRel);
+			indexInfo->ii_AmCache = (void *) bdesc;
+			MemoryContextSwitchTo(oldcxt);
+		}
+		/* First time through in this brininsert call? */
+		if (tupcxt == NULL)
+		{
 			tupcxt = AllocSetContextCreate(CurrentMemoryContext,
 										   "brininsert cxt",
 										   ALLOCSET_DEFAULT_SIZES);
-			oldcxt = MemoryContextSwitchTo(tupcxt);
+			MemoryContextSwitchTo(tupcxt);
 		}
 
 		dtup = brin_deform_tuple(bdesc, brtup);
@@ -261,12 +269,9 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
 	brinRevmapTerminate(revmap);
 	if (BufferIsValid(buf))
 		ReleaseBuffer(buf);
-	if (bdesc != NULL)
-	{
-		brin_free_desc(bdesc);
-		MemoryContextSwitchTo(oldcxt);
+	MemoryContextSwitchTo(oldcxt);
+	if (tupcxt != NULL)
 		MemoryContextDelete(tupcxt);
-	}
 
 	return false;
 }

src/backend/access/gin/gininsert.c

@@ -482,39 +482,48 @@ ginHeapTupleInsert(GinState *ginstate, OffsetNumber attnum,
 bool
 gininsert(Relation index, Datum *values, bool *isnull,
 		  ItemPointer ht_ctid, Relation heapRel,
-		  IndexUniqueCheck checkUnique)
+		  IndexUniqueCheck checkUnique,
+		  IndexInfo *indexInfo)
 {
-	GinState	ginstate;
+	GinState   *ginstate = (GinState *) indexInfo->ii_AmCache;
 	MemoryContext oldCtx;
 	MemoryContext insertCtx;
 	int			i;
 
+	/* Initialize GinState cache if first call in this statement */
+	if (ginstate == NULL)
+	{
+		oldCtx = MemoryContextSwitchTo(indexInfo->ii_Context);
+		ginstate = (GinState *) palloc(sizeof(GinState));
+		initGinState(ginstate, index);
+		indexInfo->ii_AmCache = (void *) ginstate;
+		MemoryContextSwitchTo(oldCtx);
+	}
+
 	insertCtx = AllocSetContextCreate(CurrentMemoryContext,
 									  "Gin insert temporary context",
 									  ALLOCSET_DEFAULT_SIZES);
 
 	oldCtx = MemoryContextSwitchTo(insertCtx);
 
-	initGinState(&ginstate, index);
-
 	if (GinGetUseFastUpdate(index))
 	{
 		GinTupleCollector collector;
 
 		memset(&collector, 0, sizeof(GinTupleCollector));
 
-		for (i = 0; i < ginstate.origTupdesc->natts; i++)
-			ginHeapTupleFastCollect(&ginstate, &collector,
+		for (i = 0; i < ginstate->origTupdesc->natts; i++)
+			ginHeapTupleFastCollect(ginstate, &collector,
 									(OffsetNumber) (i + 1),
 									values[i], isnull[i],
 									ht_ctid);
 
-		ginHeapTupleFastInsert(&ginstate, &collector);
+		ginHeapTupleFastInsert(ginstate, &collector);
 	}
 	else
 	{
-		for (i = 0; i < ginstate.origTupdesc->natts; i++)
-			ginHeapTupleInsert(&ginstate, (OffsetNumber) (i + 1),
+		for (i = 0; i < ginstate->origTupdesc->natts; i++)
+			ginHeapTupleInsert(ginstate, (OffsetNumber) (i + 1),
 							   values[i], isnull[i],
 							   ht_ctid);
 	}

src/backend/access/gist/gist.c

@@ -18,6 +18,7 @@
 #include "access/gistscan.h"
 #include "catalog/pg_collation.h"
 #include "miscadmin.h"
+#include "nodes/execnodes.h"
 #include "utils/builtins.h"
 #include "utils/index_selfuncs.h"
 #include "utils/memutils.h"
@@ -144,21 +145,23 @@ gistbuildempty(Relation index)
 bool
 gistinsert(Relation r, Datum *values, bool *isnull,
 		   ItemPointer ht_ctid, Relation heapRel,
-		   IndexUniqueCheck checkUnique)
+		   IndexUniqueCheck checkUnique,
+		   IndexInfo *indexInfo)
 {
+	GISTSTATE  *giststate = (GISTSTATE *) indexInfo->ii_AmCache;
 	IndexTuple	itup;
-	GISTSTATE  *giststate;
 	MemoryContext oldCxt;
 
-	giststate = initGISTstate(r);
+	/* Initialize GISTSTATE cache if first call in this statement */
+	if (giststate == NULL)
+	{
+		oldCxt = MemoryContextSwitchTo(indexInfo->ii_Context);
+		giststate = initGISTstate(r);
+		giststate->tempCxt = createTempGistContext();
+		indexInfo->ii_AmCache = (void *) giststate;
+		MemoryContextSwitchTo(oldCxt);
+	}
 
-	/*
-	 * We use the giststate's scan context as temp context too.  This means
-	 * that any memory leaked by the support functions is not reclaimed until
-	 * end of insert.  In most cases, we aren't going to call the support
-	 * functions very many times before finishing the insert, so this seems
-	 * cheaper than resetting a temp context for each function call.
-	 */
 	oldCxt = MemoryContextSwitchTo(giststate->tempCxt);
 
 	itup = gistFormTuple(giststate, r,
@@ -169,7 +172,7 @@ gistinsert(Relation r, Datum *values, bool *isnull,
 
 	/* cleanup */
 	MemoryContextSwitchTo(oldCxt);
-	freeGISTstate(giststate);
+	MemoryContextReset(giststate->tempCxt);
 
 	return false;
 }

src/backend/access/hash/hash.c

@@ -232,7 +232,8 @@ hashbuildCallback(Relation index,
 bool
 hashinsert(Relation rel, Datum *values, bool *isnull,
 		   ItemPointer ht_ctid, Relation heapRel,
-		   IndexUniqueCheck checkUnique)
+		   IndexUniqueCheck checkUnique,
+		   IndexInfo *indexInfo)
 {
 	Datum		index_values[1];
 	bool		index_isnull[1];

src/backend/access/heap/tuptoaster.c

@@ -1604,7 +1604,9 @@ toast_save_datum(Relation rel, Datum value,
 		 * Create the index entry.  We cheat a little here by not using
 		 * FormIndexDatum: this relies on the knowledge that the index columns
 		 * are the same as the initial columns of the table for all the
-		 * indexes.
+		 * indexes.  We also cheat by not providing an IndexInfo: this is okay
+		 * for now because btree doesn't need one, but we might have to be
+		 * more honest someday.
 		 *
 		 * Note also that there had better not be any user-created index on
 		 * the TOAST table, since we don't bother to update anything else.
@@ -1617,7 +1619,8 @@ toast_save_datum(Relation rel, Datum value,
 							 &(toasttup->t_self),
 							 toastrel,
 							 toastidxs[i]->rd_index->indisunique ?
-							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO);
+							 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+							 NULL);
 		}
 
 		/*

src/backend/access/index/indexam.c

@@ -196,7 +196,8 @@ index_insert(Relation indexRelation,
 			 bool *isnull,
 			 ItemPointer heap_t_ctid,
 			 Relation heapRelation,
-			 IndexUniqueCheck checkUnique)
+			 IndexUniqueCheck checkUnique,
+			 IndexInfo *indexInfo)
 {
 	RELATION_CHECKS;
 	CHECK_REL_PROCEDURE(aminsert);
@@ -208,7 +209,7 @@ index_insert(Relation indexRelation,
 
 	return indexRelation->rd_amroutine->aminsert(indexRelation, values, isnull,
 												 heap_t_ctid, heapRelation,
-												 checkUnique);
+												 checkUnique, indexInfo);
 }
 
 /*

src/backend/access/nbtree/nbtree.c

@@ -276,7 +276,8 @@ btbuildempty(Relation index)
 bool
 btinsert(Relation rel, Datum *values, bool *isnull,
 		 ItemPointer ht_ctid, Relation heapRel,
-		 IndexUniqueCheck checkUnique)
+		 IndexUniqueCheck checkUnique,
+		 IndexInfo *indexInfo)
 {
 	bool		result;
 	IndexTuple	itup;

src/backend/access/spgist/spginsert.c

@@ -206,7 +206,8 @@ spgbuildempty(Relation index)
 bool
 spginsert(Relation index, Datum *values, bool *isnull,
 		  ItemPointer ht_ctid, Relation heapRel,
-		  IndexUniqueCheck checkUnique)
+		  IndexUniqueCheck checkUnique,
+		  IndexInfo *indexInfo)
 {
 	SpGistState spgstate;
 	MemoryContext oldCtx;

src/backend/catalog/index.c

@@ -1687,6 +1687,10 @@ BuildIndexInfo(Relation index)
 	ii->ii_Concurrent = false;
 	ii->ii_BrokenHotChain = false;
 
+	/* set up for possible use by index AM */
+	ii->ii_AmCache = NULL;
+	ii->ii_Context = CurrentMemoryContext;
+
 	return ii;
 }
 
@@ -3158,7 +3162,8 @@ validate_index_heapscan(Relation heapRelation,
 						 &rootTuple,
 						 heapRelation,
 						 indexInfo->ii_Unique ?
-						 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO);
+						 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+						 indexInfo);
 
 			state->tups_inserted += 1;
 		}

src/backend/catalog/indexing.c

@@ -139,7 +139,8 @@ CatalogIndexInsert(CatalogIndexState indstate, HeapTuple heapTuple)
 					 &(heapTuple->t_self),		/* tid of heap tuple */
 					 heapRelation,
 					 relationDescs[i]->rd_index->indisunique ?
-					 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO);
+					 UNIQUE_CHECK_YES : UNIQUE_CHECK_NO,
+					 indexInfo);
 	}
 
 	ExecDropSingleTupleTableSlot(slot);

src/backend/catalog/toasting.c

@@ -315,6 +315,8 @@ create_toast_table(Relation rel, Oid toastOid, Oid toastIndexOid,
 	indexInfo->ii_ReadyForInserts = true;
 	indexInfo->ii_Concurrent = false;
 	indexInfo->ii_BrokenHotChain = false;
+	indexInfo->ii_AmCache = NULL;
+	indexInfo->ii_Context = CurrentMemoryContext;
 
 	collationObjectId[0] = InvalidOid;
 	collationObjectId[1] = InvalidOid;

src/backend/commands/constraint.c

@@ -165,7 +165,8 @@ unique_key_recheck(PG_FUNCTION_ARGS)
 		 * index will know about.
 		 */
 		index_insert(indexRel, values, isnull, &(new_row->t_self),
-					 trigdata->tg_relation, UNIQUE_CHECK_EXISTING);
+					 trigdata->tg_relation, UNIQUE_CHECK_EXISTING,
+					 indexInfo);
 	}
 	else
 	{

src/backend/commands/indexcmds.c

@@ -183,6 +183,8 @@ CheckIndexCompatible(Oid oldId,
 	indexInfo->ii_ExclusionOps = NULL;
 	indexInfo->ii_ExclusionProcs = NULL;
 	indexInfo->ii_ExclusionStrats = NULL;
+	indexInfo->ii_AmCache = NULL;
+	indexInfo->ii_Context = CurrentMemoryContext;
 	typeObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	collationObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	classObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
@@ -562,6 +564,8 @@ DefineIndex(Oid relationId,
 	indexInfo->ii_ReadyForInserts = !stmt->concurrent;
 	indexInfo->ii_Concurrent = stmt->concurrent;
 	indexInfo->ii_BrokenHotChain = false;
+	indexInfo->ii_AmCache = NULL;
+	indexInfo->ii_Context = CurrentMemoryContext;
 
 	typeObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));
 	collationObjectId = (Oid *) palloc(numberOfAttributes * sizeof(Oid));

src/backend/executor/execIndexing.c

@@ -391,7 +391,8 @@ ExecInsertIndexTuples(TupleTableSlot *slot,
 						 isnull,	/* null flags */
 						 tupleid,		/* tid of heap tuple */
 						 heapRelation,	/* heap relation */
-						 checkUnique);	/* type of uniqueness check to do */
+						 checkUnique,	/* type of uniqueness check to do */
+						 indexInfo);	/* index AM may need this */
 
 		/*
 		 * If the index has an associated exclusion constraint, check that.

src/include/access/amapi.h

@@ -72,7 +72,8 @@ typedef bool (*aminsert_function) (Relation indexRelation,
 											   bool *isnull,
 											   ItemPointer heap_tid,
 											   Relation heapRelation,
-											   IndexUniqueCheck checkUnique);
+											   IndexUniqueCheck checkUnique,
+											   struct IndexInfo *indexInfo);
 
 /* bulk delete */
 typedef IndexBulkDeleteResult *(*ambulkdelete_function) (IndexVacuumInfo *info,

src/include/access/brin_internal.h

@@ -89,7 +89,8 @@ extern IndexBuildResult *brinbuild(Relation heap, Relation index,
 extern void brinbuildempty(Relation index);
 extern bool brininsert(Relation idxRel, Datum *values, bool *nulls,
 		   ItemPointer heaptid, Relation heapRel,
-		   IndexUniqueCheck checkUnique);
+		   IndexUniqueCheck checkUnique,
+		   struct IndexInfo *indexInfo);
 extern IndexScanDesc brinbeginscan(Relation r, int nkeys, int norderbys);
 extern int64 bringetbitmap(IndexScanDesc scan, TIDBitmap *tbm);
 extern void brinrescan(IndexScanDesc scan, ScanKey scankey, int nscankeys,

src/include/access/genam.h

@@ -21,6 +21,9 @@
 #include "utils/relcache.h"
 #include "utils/snapshot.h"
 
+/* We don't want this file to depend on execnodes.h. */
+struct IndexInfo;
+
 /*
  * Struct for statistics returned by ambuild
  */
@@ -131,7 +134,8 @@ extern bool index_insert(Relation indexRelation,
 			 Datum *values, bool *isnull,
 			 ItemPointer heap_t_ctid,
 			 Relation heapRelation,
-			 IndexUniqueCheck checkUnique);
+			 IndexUniqueCheck checkUnique,
+			 struct IndexInfo *indexInfo);
 
 extern IndexScanDesc index_beginscan(Relation heapRelation,
 				Relation indexRelation,

src/include/access/gin_private.h

@@ -617,7 +617,8 @@ extern IndexBuildResult *ginbuild(Relation heap, Relation index,
 extern void ginbuildempty(Relation index);
 extern bool gininsert(Relation index, Datum *values, bool *isnull,
 		  ItemPointer ht_ctid, Relation heapRel,
-		  IndexUniqueCheck checkUnique);
+		  IndexUniqueCheck checkUnique,
+		  struct IndexInfo *indexInfo);
 extern void ginEntryInsert(GinState *ginstate,
 			   OffsetNumber attnum, Datum key, GinNullCategory category,
 			   ItemPointerData *items, uint32 nitem,

src/include/access/gist_private.h

@@ -426,7 +426,8 @@ typedef struct GiSTOptions
 extern void gistbuildempty(Relation index);
 extern bool gistinsert(Relation r, Datum *values, bool *isnull,
 		   ItemPointer ht_ctid, Relation heapRel,
-		   IndexUniqueCheck checkUnique);
+		   IndexUniqueCheck checkUnique,
+		   struct IndexInfo *indexInfo);
 extern MemoryContext createTempGistContext(void);
 extern GISTSTATE *initGISTstate(Relation index);
 extern void freeGISTstate(GISTSTATE *giststate);

src/include/access/hash.h

@@ -277,7 +277,8 @@ extern IndexBuildResult *hashbuild(Relation heap, Relation index,
 extern void hashbuildempty(Relation index);
 extern bool hashinsert(Relation rel, Datum *values, bool *isnull,
 		   ItemPointer ht_ctid, Relation heapRel,
-		   IndexUniqueCheck checkUnique);
+		   IndexUniqueCheck checkUnique,
+		   struct IndexInfo *indexInfo);
 extern bool hashgettuple(IndexScanDesc scan, ScanDirection dir);
 extern int64 hashgetbitmap(IndexScanDesc scan, TIDBitmap *tbm);
 extern IndexScanDesc hashbeginscan(Relation rel, int nkeys, int norderbys);

src/include/access/nbtree.h

@@ -659,7 +659,8 @@ extern IndexBuildResult *btbuild(Relation heap, Relation index,
 extern void btbuildempty(Relation index);
 extern bool btinsert(Relation rel, Datum *values, bool *isnull,
 		 ItemPointer ht_ctid, Relation heapRel,
-		 IndexUniqueCheck checkUnique);
+		 IndexUniqueCheck checkUnique,
+		 struct IndexInfo *indexInfo);
 extern IndexScanDesc btbeginscan(Relation rel, int nkeys, int norderbys);
 extern bool btgettuple(IndexScanDesc scan, ScanDirection dir);
 extern int64 btgetbitmap(IndexScanDesc scan, TIDBitmap *tbm);

src/include/access/spgist.h

@@ -191,7 +191,8 @@ extern IndexBuildResult *spgbuild(Relation heap, Relation index,
 extern void spgbuildempty(Relation index);
 extern bool spginsert(Relation index, Datum *values, bool *isnull,
 		  ItemPointer ht_ctid, Relation heapRel,
-		  IndexUniqueCheck checkUnique);
+		  IndexUniqueCheck checkUnique,
+		  struct IndexInfo *indexInfo);
 
 /* spgscan.c */
 extern IndexScanDesc spgbeginscan(Relation rel, int keysz, int orderbysz);

src/include/nodes/execnodes.h

@@ -52,6 +52,8 @@
  *		ReadyForInserts		is it valid for inserts?
  *		Concurrent			are we doing a concurrent index build?
  *		BrokenHotChain		did we detect any broken HOT chains?
+ *		AmCache				private cache area for index AM
+ *		Context				memory context holding this IndexInfo
  *
  * ii_Concurrent and ii_BrokenHotChain are used only during index build;
  * they're conventionally set to false otherwise.
@@ -76,6 +78,8 @@ typedef struct IndexInfo
 	bool		ii_ReadyForInserts;
 	bool		ii_Concurrent;
 	bool		ii_BrokenHotChain;
+	void	   *ii_AmCache;
+	MemoryContext ii_Context;
 } IndexInfo;
 
 /* ----------------