Add Asserts to verify that catalog cache keys are unique and not null.

The catcache code is effectively assuming this already, so let's insist
that the catalog and index are actually declared that way.

Having done that, the comments in indexing.h about non-unique indexes
not being used for catcaches are completely redundant not just mostly so;
and we didn't have such a comment for every such index anyway.  So let's
get rid of them.

Per discussion of whether we should identify primary keys for catalogs.
We might or might not take that further step, but this change in itself
will allow quicker detection of misdeclared catcaches, so it seems worth
doing in any case.

src/backend/utils/cache/catcache.c

@@ -931,7 +931,13 @@ CatalogCacheInitializeCache(CatCache *cache)
 		CatalogCacheInitializeCache_DEBUG2;
 
 		if (cache->cc_key[i] > 0)
-			keytype = tupdesc->attrs[cache->cc_key[i] - 1]->atttypid;
+		{
+			Form_pg_attribute attr = tupdesc->attrs[cache->cc_key[i] - 1];
+
+			keytype = attr->atttypid;
+			/* cache key columns should always be NOT NULL */
+			Assert(attr->attnotnull);
+		}
 		else
 		{
 			if (cache->cc_key[i] != ObjectIdAttributeNumber)
@@ -1003,6 +1009,16 @@ InitCatCachePhase2(CatCache *cache, bool touch_index)
 		 */
 		LockRelationOid(cache->cc_reloid, AccessShareLock);
 		idesc = index_open(cache->cc_indexoid, AccessShareLock);
+
+		/*
+		 * While we've got the index open, let's check that it's unique (and
+		 * not just deferrable-unique, thank you very much).  This is just to
+		 * catch thinkos in definitions of new catcaches, so we don't worry
+		 * about the pg_am indexes not getting tested.
+		 */
+		Assert(idesc->rd_index->indisunique &&
+			   idesc->rd_index->indimmediate);
+
 		index_close(idesc, AccessShareLock);
 		UnlockRelationOid(cache->cc_reloid, AccessShareLock);
 	}

src/include/catalog/indexing.h

@@ -46,7 +46,7 @@ extern void CatalogUpdateIndexes(Relation heapRel, HeapTuple heapTuple);
 
 /*
  * What follows are lines processed by genbki.pl to create the statements
- * the bootstrap parser will turn into DefineIndex commands.
+ * the bootstrap parser will turn into DefineIndex calls.
  *
  * The keyword is DECLARE_INDEX or DECLARE_UNIQUE_INDEX.  The first two
  * arguments are the index name and OID, the rest is much like a standard
@@ -114,13 +114,10 @@ DECLARE_UNIQUE_INDEX(pg_collation_name_enc_nsp_index, 3164, on pg_collation usin
 DECLARE_UNIQUE_INDEX(pg_collation_oid_index, 3085, on pg_collation using btree(oid oid_ops));
 #define CollationOidIndexId  3085
 
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_constraint_conname_nsp_index, 2664, on pg_constraint using btree(conname name_ops, connamespace oid_ops));
 #define ConstraintNameNspIndexId  2664
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_constraint_conrelid_index, 2665, on pg_constraint using btree(conrelid oid_ops));
 #define ConstraintRelidIndexId	2665
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_constraint_contypid_index, 2666, on pg_constraint using btree(contypid oid_ops));
 #define ConstraintTypidIndexId	2666
 DECLARE_UNIQUE_INDEX(pg_constraint_oid_index, 2667, on pg_constraint using btree(oid oid_ops));
@@ -138,10 +135,8 @@ DECLARE_UNIQUE_INDEX(pg_database_datname_index, 2671, on pg_database using btree
 DECLARE_UNIQUE_INDEX(pg_database_oid_index, 2672, on pg_database using btree(oid oid_ops));
 #define DatabaseOidIndexId	2672
 
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_depend_depender_index, 2673, on pg_depend using btree(classid oid_ops, objid oid_ops, objsubid int4_ops));
 #define DependDependerIndexId  2673
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_depend_reference_index, 2674, on pg_depend using btree(refclassid oid_ops, refobjid oid_ops, refobjsubid int4_ops));
 #define DependReferenceIndexId	2674
 
@@ -157,7 +152,6 @@ DECLARE_UNIQUE_INDEX(pg_enum_typid_label_index, 3503, on pg_enum using btree(enu
 DECLARE_UNIQUE_INDEX(pg_enum_typid_sortorder_index, 3534, on pg_enum using btree(enumtypid oid_ops, enumsortorder float4_ops));
 #define EnumTypIdSortOrderIndexId 3534
 
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_index_indrelid_index, 2678, on pg_index using btree(indrelid oid_ops));
 #define IndexIndrelidIndexId  2678
 DECLARE_UNIQUE_INDEX(pg_index_indexrelid_index, 2679, on pg_index using btree(indexrelid oid_ops));
@@ -165,7 +159,6 @@ DECLARE_UNIQUE_INDEX(pg_index_indexrelid_index, 2679, on pg_index using btree(in
 
 DECLARE_UNIQUE_INDEX(pg_inherits_relid_seqno_index, 2680, on pg_inherits using btree(inhrelid oid_ops, inhseqno int4_ops));
 #define InheritsRelidSeqnoIndexId  2680
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_inherits_parent_index, 2187, on pg_inherits using btree(inhparent oid_ops));
 #define InheritsParentIndexId  2187
 
@@ -213,10 +206,8 @@ DECLARE_UNIQUE_INDEX(pg_rewrite_oid_index, 2692, on pg_rewrite using btree(oid o
 DECLARE_UNIQUE_INDEX(pg_rewrite_rel_rulename_index, 2693, on pg_rewrite using btree(ev_class oid_ops, rulename name_ops));
 #define RewriteRelRulenameIndexId  2693
 
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_shdepend_depender_index, 1232, on pg_shdepend using btree(dbid oid_ops, classid oid_ops, objid oid_ops, objsubid int4_ops));
 #define SharedDependDependerIndexId		1232
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_shdepend_reference_index, 1233, on pg_shdepend using btree(refclassid oid_ops, refobjid oid_ops));
 #define SharedDependReferenceIndexId	1233
 
@@ -228,7 +219,6 @@ DECLARE_UNIQUE_INDEX(pg_tablespace_oid_index, 2697, on pg_tablespace using btree
 DECLARE_UNIQUE_INDEX(pg_tablespace_spcname_index, 2698, on pg_tablespace using btree(spcname name_ops));
 #define TablespaceNameIndexId  2698
 
-/* This following index is not used for a cache and is not unique */
 DECLARE_INDEX(pg_trigger_tgconstraint_index, 2699, on pg_trigger using btree(tgconstraint oid_ops));
 #define TriggerConstraintIndexId  2699
 DECLARE_UNIQUE_INDEX(pg_trigger_tgrelid_tgname_index, 2701, on pg_trigger using btree(tgrelid oid_ops, tgname name_ops));
@@ -271,19 +261,16 @@ DECLARE_UNIQUE_INDEX(pg_type_typname_nsp_index, 2704, on pg_type using btree(typ
 
 DECLARE_UNIQUE_INDEX(pg_foreign_data_wrapper_oid_index, 112, on pg_foreign_data_wrapper using btree(oid oid_ops));
 #define ForeignDataWrapperOidIndexId	112
-
 DECLARE_UNIQUE_INDEX(pg_foreign_data_wrapper_name_index, 548, on pg_foreign_data_wrapper using btree(fdwname name_ops));
 #define ForeignDataWrapperNameIndexId	548
 
 DECLARE_UNIQUE_INDEX(pg_foreign_server_oid_index, 113, on pg_foreign_server using btree(oid oid_ops));
 #define ForeignServerOidIndexId 113
-
 DECLARE_UNIQUE_INDEX(pg_foreign_server_name_index, 549, on pg_foreign_server using btree(srvname name_ops));
 #define ForeignServerNameIndexId	549
 
 DECLARE_UNIQUE_INDEX(pg_user_mapping_oid_index, 174, on pg_user_mapping using btree(oid oid_ops));
 #define UserMappingOidIndexId	174
-
 DECLARE_UNIQUE_INDEX(pg_user_mapping_user_server_index, 175, on pg_user_mapping using btree(umuser oid_ops, umserver oid_ops));
 #define UserMappingUserServerIndexId	175
 
@@ -306,7 +293,6 @@ DECLARE_UNIQUE_INDEX(pg_shseclabel_object_index, 3593, on pg_shseclabel using bt
 
 DECLARE_UNIQUE_INDEX(pg_extension_oid_index, 3080, on pg_extension using btree(oid oid_ops));
 #define ExtensionOidIndexId 3080
-
 DECLARE_UNIQUE_INDEX(pg_extension_name_index, 3081, on pg_extension using btree(extname name_ops));
 #define ExtensionNameIndexId 3081