Revert "Accept relations of any kind in LOCK TABLE".

Revert 59ab4ac3, as well as the followup fix 33862cb9c, in all
branches.  We need to think a bit harder about what the behavior
of LOCK TABLE on views should be, and there's no time for that
before next week's releases.  We'll take another crack at this
later.

Discussion: https://postgr.es/m/16703-e348f58aab3cf6cc@postgresql.org

doc/src/sgml/ref/lock.sgml

@@ -16,7 +16,7 @@ PostgreSQL documentation
 
  <refnamediv>
   <refname>LOCK</refname>
-  <refpurpose>lock a named relation (table, etc)</refpurpose>
+  <refpurpose>lock a table</refpurpose>
  </refnamediv>
 
  <refsynopsisdiv>
@@ -34,9 +34,7 @@ LOCK [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ * ]
   <title>Description</title>
 
   <para>
-   <command>LOCK TABLE</command> obtains a table-level lock on a
-   relation (table, partitioned table, foreign table, view,
-   materialized view, index, composite type, sequence), waiting
+   <command>LOCK TABLE</command> obtains a table-level lock, waiting
    if necessary for any conflicting locks to be released.  If
    <literal>NOWAIT</literal> is specified, <command>LOCK
    TABLE</command> does not wait to acquire the desired lock: if it
@@ -117,18 +115,17 @@ LOCK [ TABLE ] [ ONLY ] <replaceable class="parameter">name</replaceable> [ * ]
     <term><replaceable class="parameter">name</replaceable></term>
     <listitem>
      <para>
-      The name (optionally schema-qualified) of an existing relation to
-      lock. If <literal>ONLY</literal> is specified before a table name, only that
+      The name (optionally schema-qualified) of an existing table to
+      lock. If <literal>ONLY</literal> is specified before the table name, only that
       table is locked. If <literal>ONLY</literal> is not specified, the table and all
       its descendant tables (if any) are locked.  Optionally, <literal>*</literal>
       can be specified after the table name to explicitly indicate that
-      descendant tables are included.  When locking a view, all relations appearing
-      in the view definition are locked, regardless of <literal>ONLY</literal>.
+      descendant tables are included.
      </para>
 
      <para>
       The command <literal>LOCK TABLE a, b;</literal> is equivalent to
-      <literal>LOCK TABLE a; LOCK TABLE b;</literal>. The relations are locked
+      <literal>LOCK TABLE a; LOCK TABLE b;</literal>. The tables are locked
       one-by-one in the order specified in the <command>LOCK
       TABLE</command> command.
      </para>

src/backend/commands/lockcmds.c

@@ -84,6 +84,14 @@ RangeVarCallbackForLockTable(const RangeVar *rv, Oid relid, Oid oldrelid,
 		return;					/* woops, concurrently dropped; no permissions
 								 * check */
 
+	/* Currently, we only allow plain tables or views to be locked */
+	if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE &&
+		relkind != RELKIND_VIEW)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a table or view",
+						rv->relname)));
+
 	/*
 	 * Make note if a temporary relation has been accessed in this
 	 * transaction.
@@ -179,13 +187,11 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
 		foreach(rtable, query->rtable)
 		{
 			RangeTblEntry *rte = lfirst(rtable);
-			Oid			relid;
 			AclResult	aclresult;
 
-			/* ignore all non-relation RTEs */
-			if (rte->rtekind != RTE_RELATION)
-				continue;
-			relid = rte->relid;
+			Oid			relid = rte->relid;
+			char		relkind = rte->relkind;
+			char	   *relname = get_rel_name(relid);
 
 			/*
 			 * The OLD and NEW placeholder entries in the view's rtable are
@@ -196,6 +202,11 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
 				 strcmp(rte->eref->aliasname, "new") == 0))
 				continue;
 
+			/* Currently, we only allow plain tables or views to be locked. */
+			if (relkind != RELKIND_RELATION && relkind != RELKIND_PARTITIONED_TABLE &&
+				relkind != RELKIND_VIEW)
+				continue;
+
 			/*
 			 * We might be dealing with a self-referential view.  If so, we
 			 * can just stop recursing, since we already locked it.
@@ -206,8 +217,7 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
 			/* Check permissions with the view owner's privilege. */
 			aclresult = LockTableAclCheck(relid, context->lockmode, context->viewowner);
 			if (aclresult != ACLCHECK_OK)
-				aclcheck_error(aclresult, get_relkind_objtype(rte->relkind),
-							   get_rel_name(relid));
+				aclcheck_error(aclresult, get_relkind_objtype(relkind), relname);
 
 			/* We have enough rights to lock the relation; do so. */
 			if (!context->nowait)
@@ -216,9 +226,9 @@ LockViewRecurse_walker(Node *node, LockViewRecurse_context *context)
 				ereport(ERROR,
 						(errcode(ERRCODE_LOCK_NOT_AVAILABLE),
 						 errmsg("could not obtain lock on relation \"%s\"",
-								get_rel_name(relid))));
+								relname)));
 
-			if (rte->relkind == RELKIND_VIEW)
+			if (relkind == RELKIND_VIEW)
 				LockViewRecurse(relid, context->lockmode, context->nowait,
 								context->ancestor_views);
 			else if (rte->inh)

src/test/regress/expected/lock.out

@@ -12,9 +12,6 @@ CREATE VIEW lock_view3 AS SELECT * from lock_view2;
 CREATE VIEW lock_view4 AS SELECT (select a from lock_tbl1a limit 1) from lock_tbl1;
 CREATE VIEW lock_view5 AS SELECT * from lock_tbl1 where a in (select * from lock_tbl1a);
 CREATE VIEW lock_view6 AS SELECT * from (select * from lock_tbl1) sub;
-CREATE MATERIALIZED VIEW lock_mv1 AS SELECT * FROM lock_view6;
-CREATE INDEX lock_mvi1 ON lock_mv1 (a);
-CREATE SEQUENCE lock_seq;
 CREATE ROLE regress_rol_lock1;
 ALTER ROLE regress_rol_lock1 SET search_path = lock_schema1;
 GRANT USAGE ON SCHEMA lock_schema1 TO regress_rol_lock1;
@@ -155,16 +152,9 @@ BEGIN;
 LOCK TABLE ONLY lock_tbl1;
 ROLLBACK;
 RESET ROLE;
--- Lock other relations
-BEGIN TRANSACTION;
-LOCK TABLE lock_mv1;
-LOCK TABLE lock_mvi1;
-LOCK TABLE lock_seq;
-ROLLBACK;
 --
 -- Clean up
 --
-DROP MATERIALIZED VIEW lock_mv1;
 DROP VIEW lock_view7;
 DROP VIEW lock_view6;
 DROP VIEW lock_view5;
@@ -176,7 +166,6 @@ DROP TABLE lock_tbl3;
 DROP TABLE lock_tbl2;
 DROP TABLE lock_tbl1;
 DROP TABLE lock_tbl1a;
-DROP SEQUENCE lock_seq;
 DROP SCHEMA lock_schema1 CASCADE;
 DROP ROLE regress_rol_lock1;
 -- atomic ops tests

src/test/regress/sql/lock.sql

@@ -13,9 +13,6 @@ CREATE VIEW lock_view3 AS SELECT * from lock_view2;
 CREATE VIEW lock_view4 AS SELECT (select a from lock_tbl1a limit 1) from lock_tbl1;
 CREATE VIEW lock_view5 AS SELECT * from lock_tbl1 where a in (select * from lock_tbl1a);
 CREATE VIEW lock_view6 AS SELECT * from (select * from lock_tbl1) sub;
-CREATE MATERIALIZED VIEW lock_mv1 AS SELECT * FROM lock_view6;
-CREATE INDEX lock_mvi1 ON lock_mv1 (a);
-CREATE SEQUENCE lock_seq;
 CREATE ROLE regress_rol_lock1;
 ALTER ROLE regress_rol_lock1 SET search_path = lock_schema1;
 GRANT USAGE ON SCHEMA lock_schema1 TO regress_rol_lock1;
@@ -120,18 +117,9 @@ LOCK TABLE ONLY lock_tbl1;
 ROLLBACK;
 RESET ROLE;
 
--- Lock other relations
-BEGIN TRANSACTION;
-LOCK TABLE lock_mv1;
-LOCK TABLE lock_mvi1;
-LOCK TABLE lock_seq;
-ROLLBACK;
-
-
 --
 -- Clean up
 --
-DROP MATERIALIZED VIEW lock_mv1;
 DROP VIEW lock_view7;
 DROP VIEW lock_view6;
 DROP VIEW lock_view5;
@@ -142,7 +130,6 @@ DROP TABLE lock_tbl3;
 DROP TABLE lock_tbl2;
 DROP TABLE lock_tbl1;
 DROP TABLE lock_tbl1a;
-DROP SEQUENCE lock_seq;
 DROP SCHEMA lock_schema1 CASCADE;
 DROP ROLE regress_rol_lock1;