Finish reverting "recheck_on_update" patch.

This reverts commit c203d6c and some follow-on fixes, completing the
task begun in commit 5d28c9b.  If that feature is ever resurrected,
the code will look quite a bit different from this, so it seems best
to start from a clean slate.

The v11 branch is not touched; in that branch, the recheck_on_update
storage option remains present, but nonfunctional and undocumented.

Discussion: https://postgr.es/m/20190114223409.3tcvejfhlvbucrv5@alap3.anarazel.de

Author: tglsfdc

src/backend/access/common/reloptions.c

@@ -129,15 +129,6 @@ static relopt_bool boolRelOpts[] =
 		},
 		true
 	},
-	{
-		{
-			"recheck_on_update",
-			"Recheck functional index expression for changed value after update",
-			RELOPT_KIND_INDEX,
-			ShareUpdateExclusiveLock	/* since only applies to later UPDATEs */
-		},
-		true
-	},
 	{
 		{
 			"security_barrier",
@@ -1343,7 +1334,7 @@ fillRelOptions(void *rdopts, Size basesize,
 				break;
 			}
 		}
-		if (validate && !found && options[i].gen->kinds != RELOPT_KIND_INDEX)
+		if (validate && !found)
 			elog(ERROR, "reloption \"%s\" not found in parse table",
 				 options[i].gen->name);
 	}
@@ -1501,40 +1492,6 @@ index_reloptions(amoptions_function amoptions, Datum reloptions, bool validate)
 	return amoptions(reloptions, validate);
 }
 
-/*
- * Parse generic options for all indexes.
- *
- *	reloptions	options as text[] datum
- *	validate	error flag
- */
-bytea *
-index_generic_reloptions(Datum reloptions, bool validate)
-{
-	int			numoptions;
-	GenericIndexOpts *idxopts;
-	relopt_value *options;
-	static const relopt_parse_elt tab[] = {
-		{"recheck_on_update", RELOPT_TYPE_BOOL, offsetof(GenericIndexOpts, recheck_on_update)}
-	};
-
-	options = parseRelOptions(reloptions, validate,
-							  RELOPT_KIND_INDEX,
-							  &numoptions);
-
-	/* if none set, we're done */
-	if (numoptions == 0)
-		return NULL;
-
-	idxopts = allocateReloptStruct(sizeof(GenericIndexOpts), options, numoptions);
-
-	fillRelOptions((void *) idxopts, sizeof(GenericIndexOpts), options, numoptions,
-				   validate, tab, lengthof(tab));
-
-	pfree(options);
-
-	return (bytea *) idxopts;
-}
-
 /*
  * Option parser for attribute reloptions
  */

src/backend/access/heap/heapam.c

@@ -57,7 +57,6 @@
 #include "access/xlogutils.h"
 #include "catalog/catalog.h"
 #include "catalog/namespace.h"
-#include "catalog/index.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "port/atomics.h"
@@ -76,9 +75,7 @@
 #include "utils/snapmgr.h"
 #include "utils/syscache.h"
 #include "utils/tqual.h"
-#include "utils/memutils.h"
-#include "nodes/execnodes.h"
-#include "executor/executor.h"
+
 
 /* GUC variable */
 bool		synchronize_seqscans = true;
@@ -130,7 +127,6 @@ static bool ConditionalMultiXactIdWait(MultiXactId multi, MultiXactStatus status
 static XLogRecPtr log_heap_new_cid(Relation relation, HeapTuple tup);
 static HeapTuple ExtractReplicaIdentity(Relation rel, HeapTuple tup, bool key_modified,
 					   bool *copy);
-static bool ProjIndexIsUnchanged(Relation relation, HeapTuple oldtup, HeapTuple newtup);
 
 
 /*
@@ -3511,7 +3507,6 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 	HTSU_Result result;
 	TransactionId xid = GetCurrentTransactionId();
 	Bitmapset  *hot_attrs;
-	Bitmapset  *proj_idx_attrs;
 	Bitmapset  *key_attrs;
 	Bitmapset  *id_attrs;
 	Bitmapset  *interesting_attrs;
@@ -3575,11 +3570,12 @@ 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_HOT);
-	proj_idx_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_PROJ);
+	hot_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_ALL);
 	key_attrs = RelationGetIndexAttrBitmap(relation, INDEX_ATTR_BITMAP_KEY);
 	id_attrs = RelationGetIndexAttrBitmap(relation,
 										  INDEX_ATTR_BITMAP_IDENTITY_KEY);
+
+
 	block = ItemPointerGetBlockNumber(otid);
 	buffer = ReadBuffer(relation, block);
 	page = BufferGetPage(buffer);
@@ -3599,7 +3595,6 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 	if (!PageIsFull(page))
 	{
 		interesting_attrs = bms_add_members(interesting_attrs, hot_attrs);
-		interesting_attrs = bms_add_members(interesting_attrs, proj_idx_attrs);
 		hot_attrs_checked = true;
 	}
 	interesting_attrs = bms_add_members(interesting_attrs, key_attrs);
@@ -3883,7 +3878,6 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 		if (vmbuffer != InvalidBuffer)
 			ReleaseBuffer(vmbuffer);
 		bms_free(hot_attrs);
-		bms_free(proj_idx_attrs);
 		bms_free(key_attrs);
 		bms_free(id_attrs);
 		bms_free(modified_attrs);
@@ -4191,18 +4185,11 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 		/*
 		 * Since the new tuple is going into the same page, we might be able
 		 * to do a HOT update.  Check if any of the index columns have been
-		 * changed, or if we have projection functional indexes, check whether
-		 * the old and the new values are the same.   If the page was already
-		 * full, we may have skipped checking for index columns. If so, HOT
-		 * update is possible.
+		 * changed. If the page was already full, we may have skipped checking
+		 * for index columns. If so, HOT update is possible.
 		 */
-		if (hot_attrs_checked
-			&& !bms_overlap(modified_attrs, hot_attrs)
-			&& (!bms_overlap(modified_attrs, proj_idx_attrs)
-				|| ProjIndexIsUnchanged(relation, &oldtup, newtup)))
-		{
+		if (hot_attrs_checked && !bms_overlap(modified_attrs, hot_attrs))
 			use_hot_update = true;
-		}
 	}
 	else
 	{
@@ -4364,7 +4351,6 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 		heap_freetuple(old_key_tuple);
 
 	bms_free(hot_attrs);
-	bms_free(proj_idx_attrs);
 	bms_free(key_attrs);
 	bms_free(id_attrs);
 	bms_free(modified_attrs);
@@ -4450,87 +4436,6 @@ heap_tuple_attr_equals(TupleDesc tupdesc, int attrnum,
 	}
 }
 
-/*
- * Check whether the value is unchanged after update of a projection
- * functional index. Compare the new and old values of the indexed
- * expression to see if we are able to use a HOT update or not.
- */
-static bool
-ProjIndexIsUnchanged(Relation relation, HeapTuple oldtup, HeapTuple newtup)
-{
-	ListCell   *l;
-	List	   *indexoidlist = RelationGetIndexList(relation);
-	EState	   *estate = CreateExecutorState();
-	ExprContext *econtext = GetPerTupleExprContext(estate);
-	TupleTableSlot *slot = MakeSingleTupleTableSlot(RelationGetDescr(relation),
-													&TTSOpsHeapTuple);
-	bool		equals = true;
-	Datum		old_values[INDEX_MAX_KEYS];
-	bool		old_isnull[INDEX_MAX_KEYS];
-	Datum		new_values[INDEX_MAX_KEYS];
-	bool		new_isnull[INDEX_MAX_KEYS];
-	int			indexno = 0;
-
-	econtext->ecxt_scantuple = slot;
-
-	foreach(l, indexoidlist)
-	{
-		if (bms_is_member(indexno, relation->rd_projidx))
-		{
-			Oid			indexOid = lfirst_oid(l);
-			Relation	indexDesc = index_open(indexOid, AccessShareLock);
-			IndexInfo  *indexInfo = BuildIndexInfo(indexDesc);
-			int			i;
-
-			ResetExprContext(econtext);
-			ExecStoreHeapTuple(oldtup, slot, false);
-			FormIndexDatum(indexInfo,
-						   slot,
-						   estate,
-						   old_values,
-						   old_isnull);
-
-			ExecStoreHeapTuple(newtup, slot, false);
-			FormIndexDatum(indexInfo,
-						   slot,
-						   estate,
-						   new_values,
-						   new_isnull);
-
-			for (i = 0; i < indexInfo->ii_NumIndexAttrs; i++)
-			{
-				if (old_isnull[i] != new_isnull[i])
-				{
-					equals = false;
-					break;
-				}
-				else if (!old_isnull[i])
-				{
-					Form_pg_attribute att = TupleDescAttr(RelationGetDescr(indexDesc), i);
-
-					if (!datumIsEqual(old_values[i], new_values[i], att->attbyval, att->attlen))
-					{
-						equals = false;
-						break;
-					}
-				}
-			}
-			index_close(indexDesc, AccessShareLock);
-
-			if (!equals)
-			{
-				break;
-			}
-		}
-		indexno += 1;
-	}
-	ExecDropSingleTupleTableSlot(slot);
-	FreeExecutorState(estate);
-
-	return equals;
-}
-
-
 /*
  * Check which columns are being updated.
  *

src/backend/catalog/index.c

@@ -27,7 +27,6 @@
 #include "access/heapam.h"
 #include "access/multixact.h"
 #include "access/relscan.h"
-#include "access/reloptions.h"
 #include "access/sysattr.h"
 #include "access/transam.h"
 #include "access/visibilitymap.h"
@@ -355,7 +354,7 @@ ConstructTupleDescriptor(Relation heapRelation,
 			/* Simple index column */
 			const FormData_pg_attribute *from;
 
-			Assert(atnum > 0); /* should've been caught above */
+			Assert(atnum > 0);	/* should've been caught above */
 
 			if (atnum > natts)	/* safety check */
 				elog(ERROR, "invalid column number %d", atnum);
@@ -3903,7 +3902,7 @@ reindex_relation(Oid relid, int flags, int options)
 
 	/* Ensure rd_indexattr is valid; see comments for RelationSetIndexList */
 	if (is_pg_class)
-		(void) RelationGetIndexAttrBitmap(rel, INDEX_ATTR_BITMAP_HOT);
+		(void) RelationGetIndexAttrBitmap(rel, INDEX_ATTR_BITMAP_ALL);
 
 	PG_TRY();
 	{