Finish reverting "recheck_on_update" patch.

This reverts commit c203d6cf8 and some follow-on fixes, completing the
task begun in commit 5d28c9bd7.  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

1 files changed, 7 insertions, 111 deletions

diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index df30bff6c99..e3b1473e6c9 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -71,11 +71,9 @@
 #include "miscadmin.h"
 #include "nodes/nodeFuncs.h"
 #include "optimizer/clauses.h"
-#include "optimizer/cost.h"
 #include "optimizer/prep.h"
 #include "optimizer/var.h"
 #include "partitioning/partbounds.h"
-#include "pgstat.h"
 #include "rewrite/rewriteDefine.h"
 #include "rewrite/rowsecurity.h"
 #include "storage/lmgr.h"
@@ -2266,11 +2264,9 @@ RelationDestroyRelation(Relation relation, bool remember_tupdesc)
 	list_free_deep(relation->rd_fkeylist);
 	list_free(relation->rd_indexlist);
 	bms_free(relation->rd_indexattr);
-	bms_free(relation->rd_projindexattr);
 	bms_free(relation->rd_keyattr);
 	bms_free(relation->rd_pkattr);
 	bms_free(relation->rd_idattr);
-	bms_free(relation->rd_projidx);
 	if (relation->rd_pubactions)
 		pfree(relation->rd_pubactions);
 	if (relation->rd_options)
@@ -4401,7 +4397,7 @@ RelationGetStatExtList(Relation relation)
 
 	while (HeapTupleIsValid(htup = systable_getnext(indscan)))
 	{
-		Oid oid = ((Form_pg_statistic_ext) GETSTRUCT(htup))->oid;
+		Oid			oid = ((Form_pg_statistic_ext) GETSTRUCT(htup))->oid;
 
 		result = insert_ordered_oid(result, oid);
 	}
@@ -4675,77 +4671,6 @@ RelationGetIndexPredicate(Relation relation)
 	return result;
 }
 
-#define HEURISTIC_MAX_HOT_RECHECK_EXPR_COST 1000
-
-/*
- * Check if functional index is projection: index expression returns some subset
- * of its argument values. During HOT update check we handle projection indexes
- * differently: instead of checking if any of attributes used in indexed
- * expression were updated, we calculate and compare values of index expression
- * for old and new tuple values.
- *
- * Decision made by this function is based on two sources:
- * 1. Calculated cost of index expression: if greater than some heuristic limit
-	  then extra comparison of index expression values is expected to be too
-	  expensive, so we don't attempt it by default.
- * 2. "recheck_on_update" index option explicitly set by user, which overrides 1)
- */
-static bool
-IsProjectionFunctionalIndex(Relation index, IndexInfo *ii)
-{
-	bool		is_projection = false;
-
-#ifdef NOT_USED
-	if (ii->ii_Expressions)
-	{
-		HeapTuple	tuple;
-		Datum		reloptions;
-		bool		isnull;
-		QualCost	index_expr_cost;
-
-		/* by default functional index is considered as non-injective */
-		is_projection = true;
-
-		cost_qual_eval(&index_expr_cost, ii->ii_Expressions, NULL);
-
-		/*
-		 * If index expression is too expensive, then disable projection
-		 * optimization, because extra evaluation of index expression is
-		 * expected to be more expensive than index update.  Currently the
-		 * projection optimization has to calculate index expression twice
-		 * when the value of index expression has not changed and three times
-		 * when values differ because the expression is recalculated when
-		 * inserting a new index entry for the changed value.
-		 */
-		if ((index_expr_cost.startup + index_expr_cost.per_tuple) >
-			HEURISTIC_MAX_HOT_RECHECK_EXPR_COST)
-			is_projection = false;
-
-		tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(RelationGetRelid(index)));
-		if (!HeapTupleIsValid(tuple))
-			elog(ERROR, "cache lookup failed for relation %u", RelationGetRelid(index));
-
-		reloptions = SysCacheGetAttr(RELOID, tuple,
-									 Anum_pg_class_reloptions, &isnull);
-		if (!isnull)
-		{
-			GenericIndexOpts *idxopts;
-
-			idxopts = (GenericIndexOpts *) index_generic_reloptions(reloptions, false);
-
-			if (idxopts != NULL)
-			{
-				is_projection = idxopts->recheck_on_update;
-				pfree(idxopts);
-			}
-		}
-		ReleaseSysCache(tuple);
-	}
-#endif
-
-	return is_projection;
-}
-
 /*
  * RelationGetIndexAttrBitmap -- get a bitmap of index attribute numbers
  *
@@ -4773,29 +4698,24 @@ IsProjectionFunctionalIndex(Relation index, IndexInfo *ii)
 Bitmapset *
 RelationGetIndexAttrBitmap(Relation relation, IndexAttrBitmapKind attrKind)
 {
-	Bitmapset  *indexattrs;		/* columns used in non-projection indexes */
-	Bitmapset  *projindexattrs; /* columns used in projection indexes */
+	Bitmapset  *indexattrs;		/* indexed columns */
 	Bitmapset  *uindexattrs;	/* columns in unique indexes */
 	Bitmapset  *pkindexattrs;	/* columns in the primary index */
 	Bitmapset  *idindexattrs;	/* columns in the replica identity */
-	Bitmapset  *projindexes;	/* projection indexes */
 	List	   *indexoidlist;
 	List	   *newindexoidlist;
 	Oid			relpkindex;
 	Oid			relreplindex;
 	ListCell   *l;
 	MemoryContext oldcxt;
-	int			indexno;
 
 	/* Quick exit if we already computed the result. */
 	if (relation->rd_indexattr != NULL)
 	{
 		switch (attrKind)
 		{
-			case INDEX_ATTR_BITMAP_HOT:
+			case INDEX_ATTR_BITMAP_ALL:
 				return bms_copy(relation->rd_indexattr);
-			case INDEX_ATTR_BITMAP_PROJ:
-				return bms_copy(relation->rd_projindexattr);
 			case INDEX_ATTR_BITMAP_KEY:
 				return bms_copy(relation->rd_keyattr);
 			case INDEX_ATTR_BITMAP_PRIMARY_KEY:
@@ -4842,12 +4762,9 @@ restart:
 	 * won't be returned at all by RelationGetIndexList.
 	 */
 	indexattrs = NULL;
-	projindexattrs = NULL;
 	uindexattrs = NULL;
 	pkindexattrs = NULL;
 	idindexattrs = NULL;
-	projindexes = NULL;
-	indexno = 0;
 	foreach(l, indexoidlist)
 	{
 		Oid			indexOid = lfirst_oid(l);
@@ -4906,22 +4823,13 @@ restart:
 			}
 		}
 
-		/* Collect attributes used in expressions, too */
-		if (IsProjectionFunctionalIndex(indexDesc, indexInfo))
-		{
-			projindexes = bms_add_member(projindexes, indexno);
-			pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &projindexattrs);
-		}
-		else
-		{
-			/* Collect all attributes used in expressions, too */
-			pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs);
-		}
+		/* Collect all attributes used in expressions, too */
+		pull_varattnos((Node *) indexInfo->ii_Expressions, 1, &indexattrs);
+
 		/* Collect all attributes in the index predicate, too */
 		pull_varattnos((Node *) indexInfo->ii_Predicate, 1, &indexattrs);
 
 		index_close(indexDesc, AccessShareLock);
-		indexno += 1;
 	}
 
 	/*
@@ -4948,8 +4856,6 @@ restart:
 		bms_free(pkindexattrs);
 		bms_free(idindexattrs);
 		bms_free(indexattrs);
-		bms_free(projindexattrs);
-		bms_free(projindexes);
 
 		goto restart;
 	}
@@ -4957,16 +4863,12 @@ restart:
 	/* Don't leak the old values of these bitmaps, if any */
 	bms_free(relation->rd_indexattr);
 	relation->rd_indexattr = NULL;
-	bms_free(relation->rd_projindexattr);
-	relation->rd_projindexattr = NULL;
 	bms_free(relation->rd_keyattr);
 	relation->rd_keyattr = NULL;
 	bms_free(relation->rd_pkattr);
 	relation->rd_pkattr = NULL;
 	bms_free(relation->rd_idattr);
 	relation->rd_idattr = NULL;
-	bms_free(relation->rd_projidx);
-	relation->rd_projidx = NULL;
 
 	/*
 	 * Now save copies of the bitmaps in the relcache entry.  We intentionally
@@ -4980,17 +4882,13 @@ restart:
 	relation->rd_pkattr = bms_copy(pkindexattrs);
 	relation->rd_idattr = bms_copy(idindexattrs);
 	relation->rd_indexattr = bms_copy(indexattrs);
-	relation->rd_projindexattr = bms_copy(projindexattrs);
-	relation->rd_projidx = bms_copy(projindexes);
 	MemoryContextSwitchTo(oldcxt);
 
 	/* We return our original working copy for caller to play with */
 	switch (attrKind)
 	{
-		case INDEX_ATTR_BITMAP_HOT:
+		case INDEX_ATTR_BITMAP_ALL:
 			return indexattrs;
-		case INDEX_ATTR_BITMAP_PROJ:
-			return projindexattrs;
 		case INDEX_ATTR_BITMAP_KEY:
 			return uindexattrs;
 		case INDEX_ATTR_BITMAP_PRIMARY_KEY:
@@ -5619,11 +5517,9 @@ load_relcache_init_file(bool shared)
 		rel->rd_pkindex = InvalidOid;
 		rel->rd_replidindex = InvalidOid;
 		rel->rd_indexattr = NULL;
-		rel->rd_projindexattr = NULL;
 		rel->rd_keyattr = NULL;
 		rel->rd_pkattr = NULL;
 		rel->rd_idattr = NULL;
-		rel->rd_projidx = NULL;
 		rel->rd_pubactions = NULL;
 		rel->rd_statvalid = false;
 		rel->rd_statlist = NIL;