Remove pg_class.relhaspkey

It is not used for anything internally, and it cannot be relied on for
external uses, so it can just be removed.  To correct recommended way to
check for a primary key is in pg_index.

Discussion: https://www.postgresql.org/message-id/flat/b1a24c6c-6913-f89c-674e-0704f0ed69db@2ndquadrant.com

Author: petere

doc/src/sgml/catalogs.sgml

@@ -1848,15 +1848,6 @@ SCRAM-SHA-256$<replaceable>&lt;iteration count&gt;</replaceable>:<replaceable>&l
       </entry>
      </row>
 
-     <row>
-      <entry><structfield>relhaspkey</structfield></entry>
-      <entry><type>bool</type></entry>
-      <entry></entry>
-      <entry>
-       True if the table has (or once had) a primary key
-      </entry>
-     </row>
-
      <row>
       <entry><structfield>relhasrules</structfield></entry>
       <entry><type>bool</type></entry>

src/backend/catalog/heap.c

@@ -798,7 +798,6 @@ InsertPgClassTuple(Relation pg_class_desc,
 	values[Anum_pg_class_relnatts - 1] = Int16GetDatum(rd_rel->relnatts);
 	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_relhasrules - 1] = BoolGetDatum(rd_rel->relhasrules);
 	values[Anum_pg_class_relhastriggers - 1] = BoolGetDatum(rd_rel->relhastriggers);
 	values[Anum_pg_class_relrowsecurity - 1] = BoolGetDatum(rd_rel->relrowsecurity);

src/backend/catalog/index.c

@@ -125,7 +125,7 @@ static void UpdateIndexRelation(Oid indexoid, Oid heapoid,
 					bool isvalid,
 					bool isready);
 static void index_update_stats(Relation rel,
-				   bool hasindex, bool isprimary,
+				   bool hasindex,
 				   double reltuples);
 static void IndexCheckExclusion(Relation heapRelation,
 					Relation indexRelation,
@@ -1162,7 +1162,6 @@ index_create(Relation heapRelation,
 		 */
 		index_update_stats(heapRelation,
 						   true,
-						   isprimary,
 						   -1.0);
 		/* Make the above update visible */
 		CommandCounterIncrement();
@@ -1364,21 +1363,6 @@ index_constraint_create(Relation heapRelation,
 							 InvalidOid, conOid, indexRelationId, true);
 	}
 
-	/*
-	 * If needed, mark the table as having a primary key.  We assume it can't
-	 * have been so marked already, so no need to clear the flag in the other
-	 * case.
-	 *
-	 * Note: this might better be done by callers.  We do it here to avoid
-	 * exposing index_update_stats() globally, but that wouldn't be necessary
-	 * if relhaspkey went away.
-	 */
-	if (mark_as_primary)
-		index_update_stats(heapRelation,
-						   true,
-						   true,
-						   -1.0);
-
 	/*
 	 * If needed, mark the index as primary and/or deferred in pg_index.
 	 *
@@ -2041,7 +2025,6 @@ FormIndexDatum(IndexInfo *indexInfo,
  * to ensure we can do all the necessary work in just one update.
  *
  * hasindex: set relhasindex to this value
- * isprimary: if true, set relhaspkey true; else no change
  * reltuples: if >= 0, set reltuples to this value; else no change
  *
  * If reltuples >= 0, relpages and relallvisible are also updated (using
@@ -2058,7 +2041,6 @@ FormIndexDatum(IndexInfo *indexInfo,
 static void
 index_update_stats(Relation rel,
 				   bool hasindex,
-				   bool isprimary,
 				   double reltuples)
 {
 	Oid			relid = RelationGetRelid(rel);
@@ -2088,7 +2070,7 @@ 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 of course the new relpages and
+	 * it).  And of course the new relpages and
 	 * reltuples counts are correct regardless.  However, we don't want to
 	 * change relpages (or relallvisible) if the caller isn't providing an
 	 * updated reltuples count, because that would bollix the
@@ -2140,14 +2122,6 @@ index_update_stats(Relation rel,
 		rd_rel->relhasindex = hasindex;
 		dirty = true;
 	}
-	if (isprimary)
-	{
-		if (!rd_rel->relhaspkey)
-		{
-			rd_rel->relhaspkey = true;
-			dirty = true;
-		}
-	}
 
 	if (reltuples >= 0)
 	{
@@ -2356,11 +2330,9 @@ index_build(Relation heapRelation,
 	 */
 	index_update_stats(heapRelation,
 					   true,
-					   isprimary,
 					   stats->heap_tuples);
 
 	index_update_stats(indexRelation,
-					   false,
 					   false,
 					   stats->index_tuples);
 

src/backend/commands/vacuum.c

@@ -909,16 +909,6 @@ vac_update_relstats(Relation relation,
 			dirty = true;
 		}
 
-		/*
-		 * If we have discovered that there are no indexes, then there's no
-		 * primary key either.  This could be done more thoroughly...
-		 */
-		if (pgcform->relhaspkey && !hasindex)
-		{
-			pgcform->relhaspkey = false;
-			dirty = true;
-		}
-
 		/* We also clear relhasrules and relhastriggers if needed */
 		if (pgcform->relhasrules && relation->rd_rules == NULL)
 		{

src/backend/rewrite/rewriteDefine.c

@@ -618,7 +618,6 @@ DefineQueryRewrite(const char *rulename,
 		classForm->relhasindex = false;
 		classForm->relkind = RELKIND_VIEW;
 		classForm->relhasoids = false;
-		classForm->relhaspkey = false;
 		classForm->relfrozenxid = InvalidTransactionId;
 		classForm->relminmxid = InvalidMultiXactId;
 		classForm->relreplident = REPLICA_IDENTITY_NOTHING;

src/include/catalog/catversion.h

@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201803021
+#define CATALOG_VERSION_NO	201803141
 
 #endif

src/include/catalog/pg_class.h

@@ -61,7 +61,6 @@ CATALOG(pg_class,1259) BKI_BOOTSTRAP BKI_ROWTYPE_OID(83) BKI_SCHEMA_MACRO
 	 */
 	int16		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		relhasrules;	/* has (or has had) any rules */
 	bool		relhastriggers; /* has (or has had) any TRIGGERs */
 	bool		relhassubclass; /* has (or has had) derived classes */
@@ -99,7 +98,7 @@ typedef FormData_pg_class *Form_pg_class;
  * ----------------
  */
 
-#define Natts_pg_class						33
+#define Natts_pg_class						32
 #define Anum_pg_class_relname				1
 #define Anum_pg_class_relnamespace			2
 #define Anum_pg_class_reltype				3
@@ -119,20 +118,19 @@ typedef FormData_pg_class *Form_pg_class;
 #define Anum_pg_class_relnatts				17
 #define Anum_pg_class_relchecks				18
 #define Anum_pg_class_relhasoids			19
-#define Anum_pg_class_relhaspkey			20
-#define Anum_pg_class_relhasrules			21
-#define Anum_pg_class_relhastriggers		22
-#define Anum_pg_class_relhassubclass		23
-#define Anum_pg_class_relrowsecurity		24
-#define Anum_pg_class_relforcerowsecurity	25
-#define Anum_pg_class_relispopulated		26
-#define Anum_pg_class_relreplident			27
-#define Anum_pg_class_relispartition		28
-#define Anum_pg_class_relfrozenxid			29
-#define Anum_pg_class_relminmxid			30
-#define Anum_pg_class_relacl				31
-#define Anum_pg_class_reloptions			32
-#define Anum_pg_class_relpartbound			33
+#define Anum_pg_class_relhasrules			20
+#define Anum_pg_class_relhastriggers		21
+#define Anum_pg_class_relhassubclass		22
+#define Anum_pg_class_relrowsecurity		23
+#define Anum_pg_class_relforcerowsecurity	24
+#define Anum_pg_class_relispopulated		25
+#define Anum_pg_class_relreplident			26
+#define Anum_pg_class_relispartition		27
+#define Anum_pg_class_relfrozenxid			28
+#define Anum_pg_class_relminmxid			29
+#define Anum_pg_class_relacl				30
+#define Anum_pg_class_reloptions			31
+#define Anum_pg_class_relpartbound			32
 
 /* ----------------
  *		initial contents of pg_class
@@ -147,13 +145,13 @@ typedef FormData_pg_class *Form_pg_class;
  * Note: "3" in the relfrozenxid column stands for FirstNormalTransactionId;
  * similarly, "1" in relminmxid stands for FirstMultiXactId
  */
-DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1247 (  pg_type		PGNSP 71 0 PGUID 0 0 0 0 0 0 0 f f p r 30 0 t f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1249 (  pg_attribute	PGNSP 75 0 PGUID 0 0 0 0 0 0 0 f f p r 22 0 f f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 28 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1255 (  pg_proc		PGNSP 81 0 PGUID 0 0 0 0 0 0 0 f f p r 28 0 t f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");
-DATA(insert OID = 1259 (  pg_class		PGNSP 83 0 PGUID 0 0 0 0 0 0 0 f f p r 33 0 t f f f f f f t n f 3 1 _null_ _null_ _null_));
+DATA(insert OID = 1259 (  pg_class		PGNSP 83 0 PGUID 0 0 0 0 0 0 0 f f p r 32 0 t f f f f f t n f 3 1 _null_ _null_ _null_));
 DESCR("");