Add a "USING" clause to DELETE, which is equivalent to the FROM clause

in UPDATE. We also now issue a NOTICE if a query has _any_ implicit
range table entries -- in the past, we would only warn about implicit
RTEs in SELECTs with at least one explicit RTE.

As a result of the warning change, 25 of the regression tests had to
be updated. I also took the opportunity to remove some bogus whitespace
differences between some of the float4 and float8 variants. I believe
I have correctly updated all the platform-specific variants, but let
me know if that's not the case.

Original patch for DELETE ... USING from Euler Taveira de Oliveira,
reworked by Neil Conway.

Author: Neil Conway

doc/src/sgml/ref/delete.sgml

@@ -1,5 +1,5 @@
 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/delete.sgml,v 1.22 2005/01/09 05:57:45 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/delete.sgml,v 1.23 2005/04/07 01:51:37 neilc Exp $
 PostgreSQL documentation
 -->
 
@@ -20,7 +20,9 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
+DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable>
+    [ USING <replaceable class="PARAMETER">usinglist</replaceable> ]
+    [ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
 </synopsis>
  </refsynopsisdiv>
 
@@ -49,10 +51,19 @@ DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ WHERE
    <literal>ONLY</literal> clause.
   </para>
 
+  <para>
+   There are two ways to delete rows in a table using information
+   contained in other tables in the database: using sub-selects, or
+   specifying additional tables in the <literal>USING</literal> clause.
+   Which technique is more appropriate depends on the specific
+   circumstances.
+  </para>
+
   <para>
    You must have the <literal>DELETE</literal> privilege on the table
    to delete from it, as well as the <literal>SELECT</literal>
-   privilege for any table whose values are read in the <replaceable
+   privilege for any table in the <literal>USING</literal> clause or
+   whose values are read in the <replaceable
    class="parameter">condition</replaceable>.
   </para>
  </refsect1>
@@ -70,6 +81,20 @@ DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ WHERE
     </listitem>
    </varlistentry>
 
+   <varlistentry>
+    <term><replaceable class="PARAMETER">usinglist</replaceable></term>
+    <listitem>
+     <para>
+      A list of table expressions, allowing columns from other tables
+      to appear in the <literal>WHERE</> condition.  This is similar
+      to the list of tables that can be specified in the <xref
+      linkend="sql-from" endterm="sql-from-title"> of a
+      <command>SELECT</command> statement; for example, an alias for
+      the table name can be specified.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><replaceable class="parameter">condition</replaceable></term>
     <listitem>
@@ -105,10 +130,11 @@ DELETE <replaceable class="parameter">count</replaceable>
 
   <para>
    <productname>PostgreSQL</productname> lets you reference columns of
-   other tables in the <literal>WHERE</> condition.  For example, to
-   delete all films produced by a given producer, one might do
+   other tables in the <literal>WHERE</> condition by specifying the
+   other tables in the <literal>USING</literal> clause.  For example,
+   to delete all films produced by a given producer, one might do
 <programlisting>
-DELETE FROM films
+DELETE FROM films USING producers
   WHERE producer_id = producers.id AND producers.name = 'foo';
 </programlisting>
    What is essentially happening here is a join between <structname>films</>
@@ -120,10 +146,13 @@ DELETE FROM films
   WHERE producer_id IN (SELECT id FROM producers WHERE name = 'foo');
 </programlisting>
    In some cases the join style is easier to write or faster to
-   execute than the sub-select style.  One objection to the join style
-   is that there is no explicit list of what tables are being used,
-   which makes the style somewhat error-prone; also it cannot handle
-   self-joins.
+   execute than the sub-select style.
+  </para>
+
+  <para>
+   If <varname>add_missing_from</varname> is enabled, any relations
+   mentioned in the <literal>WHERE</literal> condition will be
+   implicitly added to the <literal>USING</literal> clause.
   </para>
  </refsect1>
 
@@ -149,9 +178,10 @@ DELETE FROM films;
   <title>Compatibility</title>
 
   <para>
-   This command conforms to the SQL standard, except that the ability to
-   reference other tables in the <literal>WHERE</> clause is a
-   <productname>PostgreSQL</productname> extension.
+   This command conforms to the SQL standard, except that the
+   <literal>USING</> clause and the ability to reference other tables
+   in the <literal>WHERE</> clause are <productname>PostgreSQL</>
+   extensions.
   </para>
  </refsect1>
 </refentry>

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.300 2005/04/06 16:34:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.301 2005/04/07 01:51:38 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1563,6 +1563,7 @@ _copyDeleteStmt(DeleteStmt *from)
 
 	COPY_NODE_FIELD(relation);
 	COPY_NODE_FIELD(whereClause);
+	COPY_NODE_FIELD(usingClause);
 
 	return newnode;
 }

src/backend/nodes/equalfuncs.c

@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.239 2005/04/06 16:34:05 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.240 2005/04/07 01:51:38 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -675,6 +675,7 @@ _equalDeleteStmt(DeleteStmt *a, DeleteStmt *b)
 {
 	COMPARE_NODE_FIELD(relation);
 	COMPARE_NODE_FIELD(whereClause);
+	COMPARE_NODE_FIELD(usingClause);
 
 	return true;
 }

src/backend/parser/analyze.c

@@ -6,7 +6,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.317 2005/04/06 16:34:06 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.318 2005/04/07 01:51:38 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -479,6 +479,14 @@ transformDeleteStmt(ParseState *pstate, DeleteStmt *stmt)
 
 	qry->distinctClause = NIL;
 
+	/*
+	 * The USING clause is non-standard SQL syntax, and is equivalent
+	 * in functionality to the FROM list that can be specified for
+	 * UPDATE. The USING keyword is used rather than FROM because FROM
+	 * is already a keyword in the DELETE syntax.
+	 */
+	transformFromClause(pstate, stmt->usingClause);
+
 	/* fix where clause */
 	qual = transformWhereClause(pstate, stmt->whereClause, "WHERE");
 

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.486 2005/03/31 22:46:11 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.487 2005/04/07 01:51:38 neilc Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -229,7 +229,7 @@ static void doNegateFloat(Value *v);
 				transaction_mode_list_or_empty
 				TableFuncElementList
 				prep_type_clause prep_type_list
-				execute_param_clause
+				execute_param_clause using_clause
 
 %type <range>	into_clause OptTempTableName
 
@@ -4734,15 +4734,21 @@ insert_column_item:
  *
  *****************************************************************************/
 
-DeleteStmt: DELETE_P FROM relation_expr where_clause
+DeleteStmt: DELETE_P FROM relation_expr using_clause where_clause
 				{
 					DeleteStmt *n = makeNode(DeleteStmt);
 					n->relation = $3;
-					n->whereClause = $4;
+					n->usingClause = $4;
+					n->whereClause = $5;
 					$$ = (Node *)n;
 				}
 		;
 
+using_clause:
+	    		USING from_list						{ $$ = $2; }
+			| /*EMPTY*/								{ $$ = NIL; }
+		;
+
 LockStmt:	LOCK_P opt_table qualified_name_list opt_lock opt_nowait
 				{
 					LockStmt *n = makeNode(LockStmt);

src/backend/parser/parse_relation.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.104 2005/04/06 16:34:06 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.105 2005/04/07 01:51:39 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -596,6 +596,7 @@ colNameToVar(ParseState *pstate, char *colname, bool localonly)
 				RangeTblEntry *rte = rt_fetch(varno, pstate->p_rtable);
 
 				/* joins are always inFromCl, so no need to check */
+				Assert(rte->inFromCl);
 
 				/* use orig_pstate here to get the right sublevels_up */
 				newresult = scanRTEForColumn(orig_pstate, rte, colname);
@@ -1966,17 +1967,12 @@ attnumTypeId(Relation rd, int attid)
 /*
  * Generate a warning or error about an implicit RTE, if appropriate.
  *
- * If ADD_MISSING_FROM is not enabled, raise an error.
- *
- * Our current theory on warnings is that we should allow "SELECT foo.*"
- * but warn about a mixture of explicit and implicit RTEs.
+ * If ADD_MISSING_FROM is not enabled, raise an error. Otherwise, emit
+ * a warning.
  */
 static void
 warnAutoRange(ParseState *pstate, RangeVar *relation)
 {
-	bool		foundInFromCl = false;
-	ListCell   *temp;
-
 	if (!add_missing_from)
 	{
 		if (pstate->parentParseState != NULL)
@@ -1990,19 +1986,9 @@ warnAutoRange(ParseState *pstate, RangeVar *relation)
 					 errmsg("missing FROM-clause entry for table \"%s\"",
 							relation->relname)));
 	}
-
-	foreach(temp, pstate->p_rtable)
-	{
-		RangeTblEntry *rte = lfirst(temp);
-
-		if (rte->inFromCl)
-		{
-			foundInFromCl = true;
-			break;
-		}
-	}
-	if (foundInFromCl)
+	else
 	{
+		/* just issue a warning */
 		if (pstate->parentParseState != NULL)
 			ereport(NOTICE,
 					(errcode(ERRCODE_UNDEFINED_TABLE),

src/backend/utils/adt/ruleutils.c

@@ -3,7 +3,7 @@
  *				back to source text
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.190 2005/04/06 16:34:06 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.191 2005/04/07 01:51:39 neilc Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -199,7 +199,8 @@ static void get_func_expr(FuncExpr *expr, deparse_context *context,
 static void get_agg_expr(Aggref *aggref, deparse_context *context);
 static void get_const_expr(Const *constval, deparse_context *context);
 static void get_sublink_expr(SubLink *sublink, deparse_context *context);
-static void get_from_clause(Query *query, deparse_context *context);
+static void get_from_clause(Query *query, const char *prefix,
+                            deparse_context *context);
 static void get_from_clause_item(Node *jtnode, Query *query,
 					 deparse_context *context);
 static void get_from_clause_alias(Alias *alias, int varno,
@@ -2020,7 +2021,7 @@ get_basic_select_query(Query *query, deparse_context *context,
 	}
 
 	/* Add the FROM clause if needed */
-	get_from_clause(query, context);
+	get_from_clause(query, " FROM ", context);
 
 	/* Add the WHERE clause if given */
 	if (query->jointree->quals != NULL)
@@ -2325,7 +2326,7 @@ get_update_query_def(Query *query, deparse_context *context)
 	}
 
 	/* Add the FROM clause if needed */
-	get_from_clause(query, context);
+	get_from_clause(query, " FROM ", context);
 
 	/* Finally add a WHERE clause if given */
 	if (query->jointree->quals != NULL)
@@ -2361,6 +2362,9 @@ get_delete_query_def(Query *query, deparse_context *context)
 					 only_marker(rte),
 					 generate_relation_name(rte->relid));
 
+    /* Add the USING clause if given */
+    get_from_clause(query, " USING ", context);
+
 	/* Add a WHERE clause if given */
 	if (query->jointree->quals != NULL)
 	{
@@ -3805,10 +3809,14 @@ get_sublink_expr(SubLink *sublink, deparse_context *context)
 
 /* ----------
  * get_from_clause			- Parse back a FROM clause
+ *
+ * "prefix" is the keyword that denotes the start of the list of FROM
+ * elements. It is FROM when used to parse back SELECT and UPDATE, but
+ * is USING when parsing back DELETE.
  * ----------
  */
 static void
-get_from_clause(Query *query, deparse_context *context)
+get_from_clause(Query *query, const char *prefix, deparse_context *context)
 {
 	StringInfo	buf = context->buf;
 	bool		first = true;
@@ -3840,7 +3848,7 @@ get_from_clause(Query *query, deparse_context *context)
 
 		if (first)
 		{
-			appendContextKeyword(context, " FROM ",
+			appendContextKeyword(context, prefix,
 								 -PRETTYINDENT_STD, PRETTYINDENT_STD, 2);
 			first = false;
 		}

src/bin/psql/tab-complete.c

@@ -3,7 +3,7 @@
  *
  * Copyright (c) 2000-2005, PostgreSQL Global Development Group
  *
- * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.123 2005/04/04 07:19:44 neilc Exp $
+ * $PostgreSQL: pgsql/src/bin/psql/tab-complete.c,v 1.124 2005/04/07 01:51:39 neilc Exp $
  */
 
 /*----------------------------------------------------------------------
@@ -1164,10 +1164,16 @@ psql_completion(char *text, int start, int end)
 	else if (pg_strcasecmp(prev2_wd, "DELETE") == 0 &&
 			 pg_strcasecmp(prev_wd, "FROM") == 0)
 		COMPLETE_WITH_SCHEMA_QUERY(Query_for_list_of_tables, NULL);
-	/* Complete DELETE FROM <table> with "WHERE" (perhaps a safe idea?) */
+	/* Complete DELETE FROM <table> */
 	else if (pg_strcasecmp(prev3_wd, "DELETE") == 0 &&
 			 pg_strcasecmp(prev2_wd, "FROM") == 0)
-		COMPLETE_WITH_CONST("WHERE");
+	{
+		static const char *const list_DELETE[] =
+		{"USING", "WHERE", "SET", NULL};
+
+		COMPLETE_WITH_LIST(list_DELETE);
+	}
+	/* XXX: implement tab completion for DELETE ... USING */
 
 /* EXPLAIN */
 

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.276 2005/04/06 16:34:07 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.277 2005/04/07 01:51:40 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -613,6 +613,7 @@ typedef struct DeleteStmt
 	NodeTag		type;
 	RangeVar   *relation;		/* relation to delete from */
 	Node	   *whereClause;	/* qualifications */
+	List	   *usingClause;	/* optional using clause for more tables */
 } DeleteStmt;
 
 /* ----------------------