Replace pg_class.relhasexclusion with pg_index.indisexclusion.

There isn't any need to track this state on a table-wide basis, and trying
to do so introduces undesirable semantic fuzziness.  Move the flag to
pg_index, where it clearly describes just a single index and can be
immutable after index creation.

doc/src/sgml/catalogs.sgml

@@ -1706,17 +1706,6 @@
       </entry>
      </row>
 
-     <row>
-      <entry><structfield>relhasexclusion</structfield></entry>
-      <entry><type>bool</type></entry>
-      <entry></entry>
-      <entry>
-       For a table, true if the table has (or once had) any exclusion
-       constraints; for an index, true if the index supports an exclusion
-       constraint
-      </entry>
-     </row>
-
      <row>
       <entry><structfield>relhasrules</structfield></entry>
       <entry><type>bool</type></entry>
@@ -2046,8 +2035,7 @@
    <para>
     <literal>pg_class.relchecks</literal> needs to agree with the
     number of check-constraint entries found in this table for each
-    relation.  Also, <literal>pg_class.relhasexclusion</literal> must
-    be true if there are any exclusion-constraint entries for the relation.
+    relation.
    </para>
   </note>
 
@@ -3056,12 +3044,20 @@
       (<structfield>indisunique</> should always be true when this is true)</entry>
      </row>
 
+     <row>
+      <entry><structfield>indisexclusion</structfield></entry>
+      <entry><type>bool</type></entry>
+      <entry></entry>
+      <entry>If true, this index supports an exclusion constraint</entry>
+     </row>
+
      <row>
       <entry><structfield>indimmediate</structfield></entry>
       <entry><type>bool</type></entry>
       <entry></entry>
-      <entry>If true, the uniqueness check is enforced immediately on insertion
-      (<structfield>indisunique</> should always be true when this is true)</entry>
+      <entry>If true, the uniqueness check is enforced immediately on
+       insertion
+       (irrelevant if <structfield>indisunique</> is not true)</entry>
      </row>
 
      <row>

src/backend/catalog/heap.c

@@ -703,7 +703,6 @@ InsertPgClassTuple(Relation pg_class_desc,
 	values[Anum_pg_class_relchecks - 1] = Int16GetDatum(rd_rel->relchecks);
 	values[Anum_pg_class_relhasoids - 1] = BoolGetDatum(rd_rel->relhasoids);
 	values[Anum_pg_class_relhaspkey - 1] = BoolGetDatum(rd_rel->relhaspkey);
-	values[Anum_pg_class_relhasexclusion - 1] = BoolGetDatum(rd_rel->relhasexclusion);
 	values[Anum_pg_class_relhasrules - 1] = BoolGetDatum(rd_rel->relhasrules);
 	values[Anum_pg_class_relhastriggers - 1] = BoolGetDatum(rd_rel->relhastriggers);
 	values[Anum_pg_class_relhassubclass - 1] = BoolGetDatum(rd_rel->relhassubclass);

src/backend/catalog/index.c

@@ -96,10 +96,11 @@ static void UpdateIndexRelation(Oid indexoid, Oid heapoid,
 					Oid *classOids,
 					int16 *coloptions,
 					bool primary,
+					bool isexclusion,
 					bool immediate,
 					bool isvalid);
 static void index_update_stats(Relation rel,
-				   bool hasindex, bool isprimary, bool hasexclusion,
+				   bool hasindex, bool isprimary,
 				   Oid reltoastidxid, double reltuples);
 static void IndexCheckExclusion(Relation heapRelation,
 					Relation indexRelation,
@@ -523,6 +524,7 @@ UpdateIndexRelation(Oid indexoid,
 					Oid *classOids,
 					int16 *coloptions,
 					bool primary,
+					bool isexclusion,
 					bool immediate,
 					bool isvalid)
 {
@@ -591,6 +593,7 @@ UpdateIndexRelation(Oid indexoid,
 	values[Anum_pg_index_indnatts - 1] = Int16GetDatum(indexInfo->ii_NumIndexAttrs);
 	values[Anum_pg_index_indisunique - 1] = BoolGetDatum(indexInfo->ii_Unique);
 	values[Anum_pg_index_indisprimary - 1] = BoolGetDatum(primary);
+	values[Anum_pg_index_indisexclusion - 1] = BoolGetDatum(isexclusion);
 	values[Anum_pg_index_indimmediate - 1] = BoolGetDatum(immediate);
 	values[Anum_pg_index_indisclustered - 1] = BoolGetDatum(false);
 	values[Anum_pg_index_indisvalid - 1] = BoolGetDatum(isvalid);
@@ -819,7 +822,6 @@ index_create(Relation heapRelation,
 	indexRelation->rd_rel->relam = accessMethodObjectId;
 	indexRelation->rd_rel->relkind = RELKIND_INDEX;
 	indexRelation->rd_rel->relhasoids = false;
-	indexRelation->rd_rel->relhasexclusion = is_exclusion;
 
 	/*
 	 * store index's pg_class entry
@@ -854,7 +856,7 @@ index_create(Relation heapRelation,
 	 * ----------------
 	 */
 	UpdateIndexRelation(indexRelationId, heapRelationId, indexInfo,
-						classObjectId, coloptions, isprimary,
+						classObjectId, coloptions, isprimary, is_exclusion,
 						!deferrable,
 						!concurrent);
 
@@ -1024,7 +1026,6 @@ index_create(Relation heapRelation,
 		index_update_stats(heapRelation,
 						   true,
 						   isprimary,
-						   is_exclusion,
 						   InvalidOid,
 						   heapRelation->rd_rel->reltuples);
 		/* Make the above update visible */
@@ -1190,7 +1191,6 @@ index_constraint_create(Relation heapRelation,
 		index_update_stats(heapRelation,
 						   true,
 						   true,
-						   false,
 						   InvalidOid,
 						   heapRelation->rd_rel->reltuples);
 
@@ -1375,7 +1375,7 @@ BuildIndexInfo(Relation index)
 	ii->ii_PredicateState = NIL;
 
 	/* fetch exclusion constraint info if any */
-	if (index->rd_rel->relhasexclusion)
+	if (indexStruct->indisexclusion)
 	{
 		RelationGetExclusionInfo(index,
 								 &ii->ii_ExclusionOps,
@@ -1486,7 +1486,6 @@ FormIndexDatum(IndexInfo *indexInfo,
  *
  * hasindex: set relhasindex to this value
  * isprimary: if true, set relhaspkey true; else no change
- * hasexclusion: if true, set relhasexclusion true; else no change
  * reltoastidxid: if not InvalidOid, set reltoastidxid to this value;
  *		else no change
  * reltuples: set reltuples to this value
@@ -1503,7 +1502,7 @@ FormIndexDatum(IndexInfo *indexInfo,
  */
 static void
 index_update_stats(Relation rel,
-				   bool hasindex, bool isprimary, bool hasexclusion,
+				   bool hasindex, bool isprimary,
 				   Oid reltoastidxid, double reltuples)
 {
 	BlockNumber relpages = RelationGetNumberOfBlocks(rel);
@@ -1542,9 +1541,9 @@ index_update_stats(Relation rel,
 	 * It is safe to use a non-transactional update even though our
 	 * transaction could still fail before committing.	Setting relhasindex
 	 * true is safe even if there are no indexes (VACUUM will eventually fix
-	 * it), likewise for relhaspkey and relhasexclusion.  And of course the
-	 * relpages and reltuples counts are correct (or at least more so than the
-	 * old values) regardless.
+	 * it), likewise for relhaspkey.  And of course the relpages and reltuples
+	 * counts are correct (or at least more so than the old values)
+	 * regardless.
 	 */
 
 	pg_class = heap_open(RelationRelationId, RowExclusiveLock);
@@ -1597,14 +1596,6 @@ index_update_stats(Relation rel,
 			dirty = true;
 		}
 	}
-	if (hasexclusion)
-	{
-		if (!rd_rel->relhasexclusion)
-		{
-			rd_rel->relhasexclusion = true;
-			dirty = true;
-		}
-	}
 	if (OidIsValid(reltoastidxid))
 	{
 		Assert(rd_rel->relkind == RELKIND_TOASTVALUE);
@@ -1760,13 +1751,11 @@ index_build(Relation heapRelation,
 	index_update_stats(heapRelation,
 					   true,
 					   isprimary,
-					   (indexInfo->ii_ExclusionOps != NULL),
 					   (heapRelation->rd_rel->relkind == RELKIND_TOASTVALUE) ?
 					   RelationGetRelid(indexRelation) : InvalidOid,
 					   stats->heap_tuples);
 
 	index_update_stats(indexRelation,
-					   false,
 					   false,
 					   false,
 					   InvalidOid,

src/backend/commands/vacuum.c

@@ -524,21 +524,12 @@ vac_update_relstats(Relation relation,
 
 	/*
 	 * If we have discovered that there are no indexes, then there's no
-	 * primary key either, nor any exclusion constraints.  This could be done
-	 * more thoroughly...
+	 * primary key either.  This could be done more thoroughly...
 	 */
-	if (!hasindex)
+	if (pgcform->relhaspkey && !hasindex)
 	{
-		if (pgcform->relhaspkey)
-		{
-			pgcform->relhaspkey = false;
-			dirty = true;
-		}
-		if (pgcform->relhasexclusion && pgcform->relkind != RELKIND_INDEX)
-		{
-			pgcform->relhasexclusion = false;
-			dirty = true;
-		}
+		pgcform->relhaspkey = false;
+		dirty = true;
 	}
 
 	/* We also clear relhasrules and relhastriggers if needed */

src/backend/parser/parse_utilcmd.c

@@ -949,7 +949,7 @@ generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
 	 * certainly isn't.  If it is or might be from a constraint, we have to
 	 * fetch the pg_constraint record.
 	 */
-	if (index->primary || index->unique || idxrelrec->relhasexclusion)
+	if (index->primary || index->unique || idxrec->indisexclusion)
 	{
 		Oid			constraintId = get_index_constraint(source_relid);
 
@@ -970,7 +970,7 @@ generateClonedIndexStmt(CreateStmtContext *cxt, Relation source_idx,
 			index->initdeferred = conrec->condeferred;
 
 			/* If it's an exclusion constraint, we need the operator names */
-			if (idxrelrec->relhasexclusion)
+			if (idxrec->indisexclusion)
 			{
 				Datum	   *elems;
 				int			nElems;

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201101111
+#define CATALOG_VERSION_NO	201101251
 
 #endif

src/include/catalog/pg_class.h

@@ -61,7 +61,6 @@ CATALOG(pg_class,1259) BKI_BOOTSTRAP BKI_ROWTYPE_OID(83) BKI_SCHEMA_MACRO
 	int2		relchecks;		/* # of CHECK constraints for class */
 	bool		relhasoids;		/* T if we generate OIDs for rows of rel */
 	bool		relhaspkey;		/* has (or has had) PRIMARY KEY index */
-	bool		relhasexclusion;	/* has (or has had) exclusion constraint */
 	bool		relhasrules;	/* has (or has had) any rules */
 	bool		relhastriggers; /* has (or has had) any TRIGGERs */
 	bool		relhassubclass; /* has (or has had) derived classes */
@@ -93,7 +92,7 @@ typedef FormData_pg_class *Form_pg_class;
  * ----------------
  */
 
-#define Natts_pg_class					27
+#define Natts_pg_class					26
 #define Anum_pg_class_relname			1
 #define Anum_pg_class_relnamespace		2
 #define Anum_pg_class_reltype			3
@@ -114,13 +113,12 @@ typedef FormData_pg_class *Form_pg_class;
 #define Anum_pg_class_relchecks			18
 #define Anum_pg_class_relhasoids		19
 #define Anum_pg_class_relhaspkey		20
-#define Anum_pg_class_relhasexclusion	21
-#define Anum_pg_class_relhasrules		22
-#define Anum_pg_class_relhastriggers	23
-#define Anum_pg_class_relhassubclass	24
-#define Anum_pg_class_relfrozenxid		25
-#define Anum_pg_class_relacl			26
-#define Anum_pg_class_reloptions		27
+#define Anum_pg_class_relhasrules		21
+#define Anum_pg_class_relhastriggers	22
+#define Anum_pg_class_relhassubclass	23
+#define Anum_pg_class_relfrozenxid		24
+#define Anum_pg_class_relacl			25
+#define Anum_pg_class_reloptions		26
 
 /* ----------------
  *		initial contents of pg_class
@@ -132,13 +130,13 @@ typedef FormData_pg_class *Form_pg_class;
  */
 
 /* Note: "3" in the relfrozenxid column stands for FirstNormalTransactionId */
-DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 28 0 t f f f f f 3 _null_ _null_ ));
+DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 28 0 t f f f f 3 _null_ _null_ ));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 19 0 f f f f f f 3 _null_ _null_ ));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 19 0 f f f f f 3 _null_ _null_ ));
 DESCR("");
-DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 25 0 t f f f f f 3 _null_ _null_ ));
+DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 25 0 t f f f f 3 _null_ _null_ ));
 DESCR("");
-DATA(insert OID = 1259 (  pg_class		PGNSP 83 0 PGUID 0 0 0 0 0 0 0 f f p r 27 0 t f f f f f 3 _null_ _null_ ));
+DATA(insert OID = 1259 (  pg_class		PGNSP 83 0 PGUID 0 0 0 0 0 0 0 f f p r 26 0 t f f f f 3 _null_ _null_ ));
 DESCR("");
 
 #define		  RELKIND_INDEX			  'i'		/* secondary index */

src/include/catalog/pg_index.h

@@ -35,6 +35,7 @@ CATALOG(pg_index,2610) BKI_WITHOUT_OIDS BKI_SCHEMA_MACRO
 	int2		indnatts;		/* number of columns in index */
 	bool		indisunique;	/* is this a unique index? */
 	bool		indisprimary;	/* is this index for primary key? */
+	bool		indisexclusion;	/* is this index for exclusion constraint? */
 	bool		indimmediate;	/* is uniqueness enforced immediately? */
 	bool		indisclustered; /* is this the index last clustered by? */
 	bool		indisvalid;		/* is this index valid for use by queries? */
@@ -63,22 +64,23 @@ typedef FormData_pg_index *Form_pg_index;
  *		compiler constants for pg_index
  * ----------------
  */
-#define Natts_pg_index					15
+#define Natts_pg_index					16
 #define Anum_pg_index_indexrelid		1
 #define Anum_pg_index_indrelid			2
 #define Anum_pg_index_indnatts			3
 #define Anum_pg_index_indisunique		4
 #define Anum_pg_index_indisprimary		5
-#define Anum_pg_index_indimmediate		6
-#define Anum_pg_index_indisclustered	7
-#define Anum_pg_index_indisvalid		8
-#define Anum_pg_index_indcheckxmin		9
-#define Anum_pg_index_indisready		10
-#define Anum_pg_index_indkey			11
-#define Anum_pg_index_indclass			12
-#define Anum_pg_index_indoption			13
-#define Anum_pg_index_indexprs			14
-#define Anum_pg_index_indpred			15
+#define Anum_pg_index_indisexclusion	6
+#define Anum_pg_index_indimmediate		7
+#define Anum_pg_index_indisclustered	8
+#define Anum_pg_index_indisvalid		9
+#define Anum_pg_index_indcheckxmin		10
+#define Anum_pg_index_indisready		11
+#define Anum_pg_index_indkey			12
+#define Anum_pg_index_indclass			13
+#define Anum_pg_index_indoption			14
+#define Anum_pg_index_indexprs			15
+#define Anum_pg_index_indpred			16
 
 /*
  * Index AMs that support ordered scans must support these two indoption