Add support for ALTER RULE ... RENAME TO.

Ali Dar, reviewed by Dean Rasheed.

doc/src/sgml/ref/allfiles.sgml

@@ -25,6 +25,7 @@ Complete list of usable sgml source files in this directory.
 <!ENTITY alterOperatorClass SYSTEM "alter_opclass.sgml">
 <!ENTITY alterOperatorFamily SYSTEM "alter_opfamily.sgml">
 <!ENTITY alterRole          SYSTEM "alter_role.sgml">
+<!ENTITY alterRule          SYSTEM "alter_rule.sgml">
 <!ENTITY alterSchema        SYSTEM "alter_schema.sgml">
 <!ENTITY alterServer        SYSTEM "alter_server.sgml">
 <!ENTITY alterSequence      SYSTEM "alter_sequence.sgml">

doc/src/sgml/ref/alter_rule.sgml

+<!--
+doc/src/sgml/ref/alter_rule.sgml
+PostgreSQL documentation
+-->
+
+<refentry id="SQL-ALTERRULE">
+ <refmeta>
+  <refentrytitle>ALTER RULE</refentrytitle>
+  <manvolnum>7</manvolnum>
+  <refmiscinfo>SQL - Language Statements</refmiscinfo>
+ </refmeta>
+
+ <refnamediv>
+  <refname>ALTER RULE</refname>
+  <refpurpose>change the definition of a rule</refpurpose>
+ </refnamediv>
+
+ <indexterm zone="sql-alterrule">
+  <primary>ALTER RULE</primary>
+ </indexterm>
+
+ <refsynopsisdiv>
+<synopsis>
+ALTER RULE <replaceable class="PARAMETER">name</replaceable> ON <replaceable class="PARAMETER">table_name</replaceable> RENAME TO <replaceable class="PARAMETER">new_name</replaceable>
+</synopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+  <title>Description</title>
+
+  <para>
+   <command>ALTER RULE</command> changes properties of an existing
+   rule.  Currently, the only available action is to change the rule's name.
+  </para>
+
+  <para>
+   To use <command>ALTER RULE</command>, you must own the table or view that
+   the rule applies to.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>Parameters</title>
+
+  <variablelist>
+   <varlistentry>
+    <term><replaceable class="PARAMETER">name</replaceable></term>
+    <listitem>
+     <para>
+      The name of an existing rule to alter.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="PARAMETER">table_name</replaceable></term>
+    <listitem>
+     <para>
+      The name (optionally schema-qualified) of the table or view that the
+      rule applies to.
+     </para>
+    </listitem>
+   </varlistentry>
+
+   <varlistentry>
+    <term><replaceable class="PARAMETER">new_name</replaceable></term>
+    <listitem>
+     <para>
+      The new name for the rule.
+     </para>
+    </listitem>
+   </varlistentry>
+  </variablelist>
+ </refsect1>
+
+ <refsect1>
+  <title>Examples</title>
+
+  <para>
+   To rename an existing rule:
+<programlisting>
+ALTER RULE notify_all ON emp RENAME TO notify_me;
+</programlisting></para>
+ </refsect1>
+
+ <refsect1>
+  <title>Compatibility</title>
+
+  <para>
+   <command>ALTER RULE</command> is a
+   <productname>PostgreSQL</productname> language extension, as is the
+   entire query rewrite system.
+  </para>
+ </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-createrule"></member>
+   <member><xref linkend="sql-droprule"></member>
+  </simplelist>
+ </refsect1>
+
+</refentry>

doc/src/sgml/ref/create_rule.sgml

@@ -284,4 +284,14 @@ UPDATE mytable SET name = 'foo' WHERE id = 42;
    entire query rewrite system.
   </para>
  </refsect1>
+
+ <refsect1>
+  <title>See Also</title>
+
+  <simplelist type="inline">
+   <member><xref linkend="sql-alterrule"></member>
+   <member><xref linkend="sql-droprule"></member>
+  </simplelist>
+ </refsect1>
+
 </refentry>

doc/src/sgml/ref/drop_rule.sgml

@@ -103,7 +103,9 @@ DROP RULE newrule ON mytable;
   <title>Compatibility</title>
 
   <para>
-   There is no <command>DROP RULE</command> statement in the SQL standard.
+   <command>DROP RULE</command> is a
+   <productname>PostgreSQL</productname> language extension, as is the
+   entire query rewrite system.
   </para>
  </refsect1>
 
@@ -112,6 +114,7 @@ DROP RULE newrule ON mytable;
 
   <simplelist type="inline">
    <member><xref linkend="sql-createrule"></member>
+   <member><xref linkend="sql-alterrule"></member>
   </simplelist>
  </refsect1>
 

doc/src/sgml/reference.sgml

@@ -53,6 +53,7 @@
    &alterOperatorClass;
    &alterOperatorFamily;
    &alterRole;
+   &alterRule;
    &alterSchema;
    &alterSequence;
    &alterServer;

src/backend/commands/alter.c

@@ -51,6 +51,7 @@
 #include "commands/user.h"
 #include "parser/parse_func.h"
 #include "miscadmin.h"
+#include "rewrite/rewriteDefine.h"
 #include "tcop/utility.h"
 #include "utils/builtins.h"
 #include "utils/fmgroids.h"
@@ -324,6 +325,10 @@ ExecRenameStmt(RenameStmt *stmt)
 		case OBJECT_ATTRIBUTE:
 			return renameatt(stmt);
 
+		case OBJECT_RULE:
+			return RenameRewriteRule(stmt->relation, stmt->subname,
+									 stmt->newname);
+
 		case OBJECT_TRIGGER:
 			return renametrig(stmt);
 

src/backend/parser/gram.y

@@ -7003,6 +7003,16 @@ RenameStmt: ALTER AGGREGATE func_name aggr_args RENAME TO name
 					n->missing_ok = true;
 					$$ = (Node *)n;
 				}
+			| ALTER RULE name ON qualified_name RENAME TO name
+				{
+					RenameStmt *n = makeNode(RenameStmt);
+					n->renameType = OBJECT_RULE;
+					n->relation = $5;
+					n->subname = $3;
+					n->newname = $8;
+					n->missing_ok = false;
+					$$ = (Node *)n;
+				}
 			| ALTER TRIGGER name ON qualified_name RENAME TO name
 				{
 					RenameStmt *n = makeNode(RenameStmt);

src/backend/rewrite/rewriteDefine.c

@@ -751,38 +751,99 @@ EnableDisableRule(Relation rel, const char *rulename,
 }
 
 
+/*
+ * Perform permissions and integrity checks before acquiring a relation lock.
+ */
+static void
+RangeVarCallbackForRenameRule(const RangeVar *rv, Oid relid, Oid oldrelid,
+							  void *arg)
+{
+	HeapTuple	tuple;
+	Form_pg_class form;
+
+	tuple = SearchSysCache1(RELOID, ObjectIdGetDatum(relid));
+	if (!HeapTupleIsValid(tuple))
+		return;					/* concurrently dropped */
+	form = (Form_pg_class) GETSTRUCT(tuple);
+
+	/* only tables and views can have rules */
+	if (form->relkind != RELKIND_RELATION && form->relkind != RELKIND_VIEW)
+		ereport(ERROR,
+				(errcode(ERRCODE_WRONG_OBJECT_TYPE),
+				 errmsg("\"%s\" is not a table or view", rv->relname)));
+
+	if (!allowSystemTableMods && IsSystemClass(form))
+		ereport(ERROR,
+				(errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
+				 errmsg("permission denied: \"%s\" is a system catalog",
+						rv->relname)));
+
+	/* you must own the table to rename one of its rules */
+	if (!pg_class_ownercheck(relid, GetUserId()))
+		aclcheck_error(ACLCHECK_NOT_OWNER, ACL_KIND_CLASS, rv->relname);
+
+	ReleaseSysCache(tuple);
+}
+
 /*
  * Rename an existing rewrite rule.
- *
- * This is unused code at the moment.  Note that it lacks a permissions check.
  */
-#ifdef NOT_USED
-void
-RenameRewriteRule(Oid owningRel, const char *oldName,
+Oid
+RenameRewriteRule(RangeVar *relation, const char *oldName,
 				  const char *newName)
 {
+	Oid			relid;
+	Relation	targetrel;
 	Relation	pg_rewrite_desc;
 	HeapTuple	ruletup;
+	Form_pg_rewrite ruleform;
+	Oid			ruleOid;
 
+	/*
+	 * Look up name, check permissions, and acquire lock (which we will NOT
+	 * release until end of transaction).
+	 */
+	relid = RangeVarGetRelidExtended(relation, AccessExclusiveLock,
+									 false, false,
+									 RangeVarCallbackForRenameRule,
+									 NULL);
+
+	/* Have lock already, so just need to build relcache entry. */
+	targetrel = relation_open(relid, NoLock);
+
+	/* Prepare to modify pg_rewrite */
 	pg_rewrite_desc = heap_open(RewriteRelationId, RowExclusiveLock);
 
+	/* Fetch the rule's entry (it had better exist) */
 	ruletup = SearchSysCacheCopy2(RULERELNAME,
-								  ObjectIdGetDatum(owningRel),
+								  ObjectIdGetDatum(relid),
 								  PointerGetDatum(oldName));
 	if (!HeapTupleIsValid(ruletup))
 		ereport(ERROR,
 				(errcode(ERRCODE_UNDEFINED_OBJECT),
 				 errmsg("rule \"%s\" for relation \"%s\" does not exist",
-						oldName, get_rel_name(owningRel))));
+						oldName, RelationGetRelationName(targetrel))));
+	ruleform = (Form_pg_rewrite) GETSTRUCT(ruletup);
+	ruleOid = HeapTupleGetOid(ruletup);
 
-	/* should not already exist */
-	if (IsDefinedRewriteRule(owningRel, newName))
+	/* rule with the new name should not already exist */
+	if (IsDefinedRewriteRule(relid, newName))
 		ereport(ERROR,
 				(errcode(ERRCODE_DUPLICATE_OBJECT),
 				 errmsg("rule \"%s\" for relation \"%s\" already exists",
-						newName, get_rel_name(owningRel))));
+						newName, RelationGetRelationName(targetrel))));
+
+	/*
+	 * We disallow renaming ON SELECT rules, because they should always be
+	 * named "_RETURN".
+	 */
+	if (ruleform->ev_type == CMD_SELECT + '0')
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_OBJECT_DEFINITION),
+				 errmsg("renaming an ON SELECT rule is not allowed")));
 
-	namestrcpy(&(((Form_pg_rewrite) GETSTRUCT(ruletup))->rulename), newName);
+	/* OK, do the update */
+	namestrcpy(&(ruleform->rulename), newName);
 
 	simple_heap_update(pg_rewrite_desc, &ruletup->t_self, ruletup);
 
@@ -791,6 +852,18 @@ RenameRewriteRule(Oid owningRel, const char *oldName,
 
 	heap_freetuple(ruletup);
 	heap_close(pg_rewrite_desc, RowExclusiveLock);
-}
 
-#endif
+	/*
+	 * Invalidate relation's relcache entry so that other backends (and this
+	 * one too!) are sent SI message to make them rebuild relcache entries.
+	 * (Ideally this should happen automatically...)
+	 */
+	CacheInvalidateRelcache(targetrel);
+
+	/*
+	 * Close rel, but keep exclusive lock!
+	 */
+	relation_close(targetrel, NoLock);
+
+	return ruleOid;
+}

src/bin/psql/tab-complete.c

@@ -624,6 +624,15 @@ static const SchemaQuery Query_for_list_of_views = {
 "       (SELECT conrelid FROM pg_catalog.pg_constraint "\
 "         WHERE pg_catalog.quote_ident(conname)='%s')"
 
+/* the silly-looking length condition is just to eat up the current word */
+#define Query_for_list_of_tables_for_rule \
+"SELECT pg_catalog.quote_ident(relname) "\
+"  FROM pg_catalog.pg_class"\
+" WHERE (%d = pg_catalog.length('%s'))"\
+"   AND oid IN "\
+"       (SELECT ev_class FROM pg_catalog.pg_rewrite "\
+"         WHERE pg_catalog.quote_ident(rulename)='%s')"
+
 /* the silly-looking length condition is just to eat up the current word */
 #define Query_for_list_of_tables_for_trigger \
 "SELECT pg_catalog.quote_ident(relname) "\
@@ -925,7 +934,7 @@ psql_completion(char *text, int start, int end)
 		{"AGGREGATE", "COLLATION", "CONVERSION", "DATABASE", "DEFAULT PRIVILEGES", "DOMAIN",
 			"EXTENSION", "FOREIGN DATA WRAPPER", "FOREIGN TABLE", "FUNCTION",
 			"GROUP", "INDEX", "LANGUAGE", "LARGE OBJECT", "OPERATOR",
-			"ROLE", "SCHEMA", "SERVER", "SEQUENCE", "TABLE",
+			"ROLE", "RULE", "SCHEMA", "SERVER", "SEQUENCE", "TABLE",
 			"TABLESPACE", "TEXT SEARCH", "TRIGGER", "TYPE",
 		"USER", "USER MAPPING FOR", "VIEW", NULL};
 
@@ -1259,6 +1268,26 @@ psql_completion(char *text, int start, int end)
 
 		COMPLETE_WITH_LIST(list_ALTERVIEW);
 	}
+
+	/* ALTER RULE <name>, add ON */
+	else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
+			 pg_strcasecmp(prev2_wd, "RULE") == 0)
+		COMPLETE_WITH_CONST("ON");
+
+	/* If we have ALTER RULE <name> ON, then add the correct tablename */
+	else if (pg_strcasecmp(prev4_wd, "ALTER") == 0 &&
+			 pg_strcasecmp(prev3_wd, "RULE") == 0 &&
+			 pg_strcasecmp(prev_wd, "ON") == 0)
+	{
+		completion_info_charp = prev2_wd;
+		COMPLETE_WITH_QUERY(Query_for_list_of_tables_for_rule);
+	}
+
+	/* ALTER RULE <name> ON <name> */
+	else if (pg_strcasecmp(prev5_wd, "ALTER") == 0 &&
+			 pg_strcasecmp(prev4_wd, "RULE") == 0)
+		COMPLETE_WITH_CONST("RENAME TO");
+
 	/* ALTER TRIGGER <name>, add ON */
 	else if (pg_strcasecmp(prev3_wd, "ALTER") == 0 &&
 			 pg_strcasecmp(prev2_wd, "TRIGGER") == 0)

src/include/rewrite/rewriteDefine.h

@@ -32,7 +32,7 @@ extern Oid DefineQueryRewrite(char *rulename,
 				   bool replace,
 				   List *action);
 
-extern void RenameRewriteRule(Oid owningRel, const char *oldName,
+extern Oid RenameRewriteRule(RangeVar *relation, const char *oldName,
 				  const char *newName);
 
 extern void setRuleCheckAsUser(Node *node, Oid userid);

src/test/regress/expected/rules.out

@@ -2559,3 +2559,44 @@ Rules:
     ON UPDATE TO rules_src DO  VALUES (old.f1,old.f2,'old'::text), (new.f1,new.f2,'new'::text)
 Has OIDs: no
 
+--
+-- check alter rename rule
+--
+CREATE TABLE rule_t1 (a INT);
+CREATE VIEW rule_v1 AS SELECT * FROM rule_t1;
+CREATE RULE InsertRule AS
+    ON INSERT TO rule_v1
+    DO INSTEAD
+        INSERT INTO rule_t1 VALUES(new.a);
+ALTER RULE InsertRule ON rule_v1 RENAME to NewInsertRule;
+INSERT INTO rule_v1 VALUES(1);
+SELECT * FROM rule_v1;
+ a 
+---
+ 1
+(1 row)
+
+\d+ rule_v1
+                View "public.rule_v1"
+ Column |  Type   | Modifiers | Storage | Description 
+--------+---------+-----------+---------+-------------
+ a      | integer |           | plain   | 
+View definition:
+ SELECT rule_t1.a
+   FROM rule_t1;
+Rules:
+ newinsertrule AS
+    ON INSERT TO rule_v1 DO INSTEAD  INSERT INTO rule_t1 (a) 
+  VALUES (new.a)
+
+--
+-- error conditions for alter rename rule
+--
+ALTER RULE InsertRule ON rule_v1 RENAME TO NewInsertRule; -- doesn't exist
+ERROR:  rule "insertrule" for relation "rule_v1" does not exist
+ALTER RULE NewInsertRule ON rule_v1 RENAME TO "_RETURN"; -- already exists
+ERROR:  rule "_RETURN" for relation "rule_v1" already exists
+ALTER RULE "_RETURN" ON rule_v1 RENAME TO abc; -- ON SELECT rule cannot be renamed
+ERROR:  renaming an ON SELECT rule is not allowed
+DROP VIEW rule_v1;
+DROP TABLE rule_t1;

src/test/regress/sql/rules.sql

@@ -968,3 +968,31 @@ update rules_src set f2 = f2 / 10;
 select * from rules_src;
 select * from rules_log;
 \d+ rules_src
+
+--
+-- check alter rename rule
+--
+CREATE TABLE rule_t1 (a INT);
+CREATE VIEW rule_v1 AS SELECT * FROM rule_t1;
+
+CREATE RULE InsertRule AS
+    ON INSERT TO rule_v1
+    DO INSTEAD
+        INSERT INTO rule_t1 VALUES(new.a);
+
+ALTER RULE InsertRule ON rule_v1 RENAME to NewInsertRule;
+
+INSERT INTO rule_v1 VALUES(1);
+SELECT * FROM rule_v1;
+
+\d+ rule_v1
+
+--
+-- error conditions for alter rename rule
+--
+ALTER RULE InsertRule ON rule_v1 RENAME TO NewInsertRule; -- doesn't exist
+ALTER RULE NewInsertRule ON rule_v1 RENAME TO "_RETURN"; -- already exists
+ALTER RULE "_RETURN" ON rule_v1 RENAME TO abc; -- ON SELECT rule cannot be renamed
+
+DROP VIEW rule_v1;
+DROP TABLE rule_t1;