From 012abebab1bc72043f3f670bf32e91ae4ee04bd2 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 7 Mar 2006 01:00:19 +0000
Subject: [PATCH] Remove the stub support we had for UNION JOIN; per
 discussion, this is not likely ever to be implemented seeing it's been
 removed from SQL2003. This allows getting rid of the 'filter' version of
 yylex() that we had in parser.c, which should save at least a few
 microseconds in parsing.

---
 src/backend/optimizer/path/clausesel.c    |  4 +-
 src/backend/optimizer/plan/initsplan.c    | 14 +-----
 src/backend/optimizer/prep/prepjointree.c | 12 +----
 src/backend/parser/Makefile               |  7 ++-
 src/backend/parser/gram.y                 | 25 ++--------
 src/backend/parser/parser.c               | 58 ++---------------------
 src/backend/parser/scan.l                 |  4 +-
 src/backend/utils/adt/ruleutils.c         | 12 +----
 src/include/nodes/nodes.h                 |  9 +---
 src/include/parser/gramparse.h            |  9 ++--
 src/interfaces/ecpg/preproc/preproc.y     | 12 +----
 src/test/regress/expected/join.out        |  4 --
 src/test/regress/expected/join_1.out      |  4 --
 src/test/regress/sql/join.sql             |  4 --
 14 files changed, 20 insertions(+), 158 deletions(-)

diff --git a/src/backend/optimizer/path/clausesel.c b/src/backend/optimizer/path/clausesel.c
index 37d438fefce..3ff02902f7c 100644
--- a/src/backend/optimizer/path/clausesel.c
+++ b/src/backend/optimizer/path/clausesel.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.78 2006/03/05 15:58:28 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/path/clausesel.c,v 1.79 2006/03/07 01:00:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -449,8 +449,6 @@ clause_selectivity(PlannerInfo *root,
 					cacheable = true;
 					break;
 
-				case JOIN_UNION:
-					/* unimplemented anyway... */
 				case JOIN_IN:
 				case JOIN_REVERSE_IN:
 				case JOIN_UNIQUE_OUTER:
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index 21b10cf817c..d980cde06bc 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.115 2006/03/05 15:58:29 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.116 2006/03/07 01:00:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -363,18 +363,6 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join,
 				*qualscope = bms_union(leftids, rightids);
 				nonnullable_rels = leftids;
 				break;
-			case JOIN_UNION:
-
-				/*
-				 * This is where we fail if upper levels of planner haven't
-				 * rewritten UNION JOIN as an Append ...
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-						 errmsg("UNION JOIN is not implemented")));
-				nonnullable_rels = NULL;		/* keep compiler quiet */
-				leftjoinlist = rightjoinlist = NIL;
-				break;
 			default:
 				elog(ERROR, "unrecognized join type: %d",
 					 (int) j->jointype);
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index c318b89d39c..ae538c9cc00 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -15,7 +15,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.36 2006/03/05 15:58:30 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/optimizer/prep/prepjointree.c,v 1.37 2006/03/07 01:00:15 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -242,16 +242,6 @@ pull_up_subqueries(PlannerInfo *root, Node *jtnode,
 				j->rarg = pull_up_subqueries(root, j->rarg,
 											 below_outer_join, false);
 				break;
-			case JOIN_UNION:
-
-				/*
-				 * This is where we fail if upper levels of planner haven't
-				 * rewritten UNION JOIN as an Append ...
-				 */
-				ereport(ERROR,
-						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-						 errmsg("UNION JOIN is not implemented")));
-				break;
 			default:
 				elog(ERROR, "unrecognized join type: %d",
 					 (int) j->jointype);
diff --git a/src/backend/parser/Makefile b/src/backend/parser/Makefile
index da5ac26ed67..553fda257e1 100644
--- a/src/backend/parser/Makefile
+++ b/src/backend/parser/Makefile
@@ -2,7 +2,7 @@
 #
 # Makefile for parser
 #
-# $PostgreSQL: pgsql/src/backend/parser/Makefile,v 1.42 2003/11/29 19:51:51 pgsql Exp $
+# $PostgreSQL: pgsql/src/backend/parser/Makefile,v 1.43 2006/03/07 01:00:17 tgl Exp $
 #
 #-------------------------------------------------------------------------
 
@@ -57,8 +57,7 @@ endif
 
 
 # Force these dependencies to be known even without dependency info built:
-
-gram.o keywords.o parser.o: $(srcdir)/parse.h
+gram.o keywords.o: $(srcdir)/parse.h
 
 
 # gram.c, parse.h, and scan.c are in the distribution tarball, so they
@@ -66,4 +65,4 @@ gram.o keywords.o parser.o: $(srcdir)/parse.h
 clean: 
 	rm -f SUBSYS.o $(OBJS)
 # And the garbage that might have been left behind by partial build:
-	@rm -f y.tab.c y.tab.h lex.yy.c
+	@rm -f y.tab.h y.tab.c y.output lex.yy.c
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index 135f2272def..c86a6888f20 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.533 2006/03/05 15:58:32 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.534 2006/03/07 01:00:16 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -95,6 +95,7 @@ static void doNegateFloat(Value *v);
 
 %}
 
+%name-prefix="base_yy"
 
 %union
 {
@@ -418,12 +419,6 @@ static void doNegateFloat(Value *v);
 
 	ZONE
 
-/* The grammar thinks these are keywords, but they are not in the keywords.c
- * list and so can never be entered directly.  The filter in parser.c
- * creates these tokens when required.
- */
-%token			UNIONJOIN
-
 /* Special token types, not actually keywords - see the "lex" file */
 %token <str>	IDENT FCONST SCONST BCONST XCONST Op
 %token <ival>	ICONST PARAM
@@ -464,7 +459,7 @@ static void doNegateFloat(Value *v);
  * They wouldn't be given a precedence at all, were it not that we need
  * left-associativity among the JOIN rules themselves.
  */
-%left		JOIN UNIONJOIN CROSS LEFT FULL RIGHT INNER_P NATURAL
+%left		JOIN CROSS LEFT FULL RIGHT INNER_P NATURAL
 %%
 
 /*
@@ -5774,20 +5769,6 @@ joined_table:
 					n->quals = NULL;
 					$$ = n;
 				}
-			| table_ref UNIONJOIN table_ref
-				{
-					/* UNION JOIN is made into 1 token to avoid shift/reduce
-					 * conflict against regular UNION keyword.
-					 */
-					JoinExpr *n = makeNode(JoinExpr);
-					n->jointype = JOIN_UNION;
-					n->isNatural = FALSE;
-					n->larg = $1;
-					n->rarg = $3;
-					n->using = NIL;
-					n->quals = NULL;
-					$$ = n;
-				}
 			| table_ref join_type JOIN table_ref join_qual
 				{
 					JoinExpr *n = makeNode(JoinExpr);
diff --git a/src/backend/parser/parser.c b/src/backend/parser/parser.c
index 4b5d12c0bf4..6c331ad338d 100644
--- a/src/backend/parser/parser.c
+++ b/src/backend/parser/parser.c
@@ -7,32 +7,26 @@
  * (since we need to be able to do basic parsing even while inside an
  * aborted transaction).  Therefore, the data structures returned by
  * the grammar are "raw" parsetrees that still need to be analyzed by
- * parse_analyze.
+ * analyze.c and related files.
  *
  *
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parser.c,v 1.64 2006/03/05 15:58:34 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parser.c,v 1.65 2006/03/07 01:00:17 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
 
 #include "postgres.h"
 
-#include "nodes/parsenodes.h"
 #include "parser/gramparse.h"
-#include "parser/parse.h"
 #include "parser/parser.h"
-#include "parser/parse_expr.h"
 
 
 List	   *parsetree;			/* result of parsing is left here */
 
-static int	lookahead_token;	/* one-token lookahead */
-static bool have_lookahead;		/* lookahead_token set? */
-
 
 /*
  * raw_parser
@@ -46,12 +40,11 @@ raw_parser(const char *str)
 	int			yyresult;
 
 	parsetree = NIL;			/* in case grammar forgets to set it */
-	have_lookahead = false;
 
 	scanner_init(str);
 	parser_init();
 
-	yyresult = yyparse();
+	yyresult = base_yyparse();
 
 	scanner_finish();
 
@@ -60,48 +53,3 @@ raw_parser(const char *str)
 
 	return parsetree;
 }
-
-
-/*
- * Intermediate filter between parser and base lexer (base_yylex in scan.l).
- *
- * The filter is needed because in some cases SQL92 requires more than one
- * token lookahead.  We reduce these cases to one-token lookahead by combining
- * tokens here, in order to keep the grammar LR(1).
- *
- * Using a filter is simpler than trying to recognize multiword tokens
- * directly in scan.l, because we'd have to allow for comments between the
- * words ...
- */
-int
-yylex(void)
-{
-	int			cur_token;
-
-	/* Get next token --- we might already have it */
-	if (have_lookahead)
-	{
-		cur_token = lookahead_token;
-		have_lookahead = false;
-	}
-	else
-		cur_token = base_yylex();
-
-	/* Do we need to look ahead for a possible multiword token? */
-	switch (cur_token)
-	{
-		case UNION:
-			/* UNION JOIN must be reduced to a single UNIONJOIN token */
-			lookahead_token = base_yylex();
-			if (lookahead_token == JOIN)
-				cur_token = UNIONJOIN;
-			else
-				have_lookahead = true;
-			break;
-
-		default:
-			break;
-	}
-
-	return cur_token;
-}
diff --git a/src/backend/parser/scan.l b/src/backend/parser/scan.l
index e277920ee20..3d63cb73c8a 100644
--- a/src/backend/parser/scan.l
+++ b/src/backend/parser/scan.l
@@ -24,7 +24,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.131 2006/03/06 19:49:20 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/scan.l,v 1.132 2006/03/07 01:00:17 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -45,8 +45,6 @@
 #undef fprintf
 #define fprintf(file, fmt, msg)  ereport(ERROR, (errmsg_internal("%s", msg)))
 
-extern YYSTYPE yylval;
-
 static int		xcdepth = 0;	/* depth of nesting in slash-star comments */
 static char    *dolqstart;      /* current $foo$ quote start string */
 
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 05e817ecc08..d6e8907c73f 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -3,7 +3,7 @@
  *				back to source text
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.213 2006/01/26 17:08:19 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/ruleutils.c,v 1.214 2006/03/07 01:00:17 tgl Exp $
  *
  *	  This software is copyrighted by Jan Wieck - Hamburg.
  *
@@ -4357,11 +4357,6 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 										 -PRETTYINDENT_JOIN,
 										 PRETTYINDENT_JOIN, 0);
 					break;
-				case JOIN_UNION:
-					appendContextKeyword(context, "NATURAL UNION JOIN ",
-										 -PRETTYINDENT_JOIN,
-										 PRETTYINDENT_JOIN, 0);
-					break;
 				default:
 					elog(ERROR, "unrecognized join type: %d",
 						 (int) j->jointype);
@@ -4396,11 +4391,6 @@ get_from_clause_item(Node *jtnode, Query *query, deparse_context *context)
 										 -PRETTYINDENT_JOIN,
 										 PRETTYINDENT_JOIN, 2);
 					break;
-				case JOIN_UNION:
-					appendContextKeyword(context, " UNION JOIN ",
-										 -PRETTYINDENT_JOIN,
-										 PRETTYINDENT_JOIN, 2);
-					break;
 				default:
 					elog(ERROR, "unrecognized join type: %d",
 						 (int) j->jointype);
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index b092563e41c..b8415378d95 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.183 2006/03/05 15:58:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/nodes.h,v 1.184 2006/03/07 01:00:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -457,13 +457,6 @@ typedef enum JoinType
 	JOIN_FULL,					/* pairs + unmatched outer + unmatched inner */
 	JOIN_RIGHT,					/* pairs + unmatched inner tuples */
 
-	/*
-	 * SQL92 considers UNION JOIN to be a kind of join, so list it here for
-	 * parser convenience, even though it's not implemented like a join in the
-	 * executor.  (The planner must convert it to an Append plan.)
-	 */
-	JOIN_UNION,
-
 	/*
 	 * These are used for queries like WHERE foo IN (SELECT bar FROM ...).
 	 * Only JOIN_IN is actually implemented in the executor; the others are
diff --git a/src/include/parser/gramparse.h b/src/include/parser/gramparse.h
index eb043965d0d..054604521bc 100644
--- a/src/include/parser/gramparse.h
+++ b/src/include/parser/gramparse.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/parser/gramparse.h,v 1.32 2006/03/05 15:58:57 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/parser/gramparse.h,v 1.33 2006/03/07 01:00:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,18 +18,15 @@
 #include "nodes/parsenodes.h"
 
 
-/* from parser.c */
-extern int	yylex(void);
-
 /* from scan.l */
 extern void scanner_init(const char *str);
 extern void scanner_finish(void);
 extern int	base_yylex(void);
-extern void yyerror(const char *message);
+extern void base_yyerror(const char *message);
 
 /* from gram.y */
 extern void parser_init(void);
-extern int	yyparse(void);
+extern int	base_yyparse(void);
 extern List *SystemFuncName(char *name);
 extern TypeName *SystemTypeName(char *name);
 extern bool exprIsNullConstant(Node *arg);
diff --git a/src/interfaces/ecpg/preproc/preproc.y b/src/interfaces/ecpg/preproc/preproc.y
index 4c07d4218c0..c73aa41a19f 100644
--- a/src/interfaces/ecpg/preproc/preproc.y
+++ b/src/interfaces/ecpg/preproc/preproc.y
@@ -1,4 +1,4 @@
-/* $PostgreSQL: pgsql/src/interfaces/ecpg/preproc/preproc.y,v 1.320 2006/02/08 09:10:04 meskes Exp $ */
+/* $PostgreSQL: pgsql/src/interfaces/ecpg/preproc/preproc.y,v 1.321 2006/03/07 01:00:19 tgl Exp $ */
 
 /* Copyright comment */
 %{
@@ -426,12 +426,6 @@ add_additional_variables(char *name, bool insert)
 	YEAR_P
 	ZONE
 
-/* The grammar thinks these are keywords, but they are not in the keywords.c
- * list and so can never be entered directly.  The filter in parser.c
- * creates these tokens when required.
- */
-%token	UNIONJOIN
-
 /* Special token types, not actually keywords - see the "lex" file */
 %token <str>	IDENT SCONST Op CSTRING CVARIABLE CPP_LINE IP BCONST XCONST DOLCONST
 %token <ival>	ICONST PARAM
@@ -465,7 +459,7 @@ add_additional_variables(char *name, bool insert)
 %left		'(' ')'
 %left		TYPECAST
 %left		'.'
-%left		JOIN UNIONJOIN CROSS LEFT FULL RIGHT INNER_P NATURAL
+%left		JOIN CROSS LEFT FULL RIGHT INNER_P NATURAL
 
 %type  <str>	Iconst Fconst Sconst TransactionStmt CreateStmt RoleId
 %type  <str>	CreateAsElement OptCreateAs CreateAsList CreateAsStmt
@@ -3391,8 +3385,6 @@ joined_table:  '(' joined_table ')'
 			{ $$ = cat_str(3, make_str("("), $2, make_str(")")); }
 		| table_ref CROSS JOIN table_ref
 			{ $$ = cat_str(3, $1, make_str("cross join"), $4); }
-		| table_ref UNIONJOIN table_ref
-			{ $$ = cat_str(3, $1, make_str("unionjoin"), $3); }
 		| table_ref join_type JOIN table_ref join_qual
 			{ $$ = cat_str(5, $1, $2, make_str("join"), $4, $5); }
 		| table_ref JOIN table_ref join_qual
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 614f6f07858..0a7c5605cd2 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -1846,10 +1846,6 @@ SELECT '' AS "xxx", *
 --
 -- More complicated constructs
 --
--- UNION JOIN isn't implemented yet
-SELECT '' AS "xxx", *
-  FROM J1_TBL UNION JOIN J2_TBL;
-ERROR:  UNION JOIN is not implemented
 --
 -- Multiway full join
 --
diff --git a/src/test/regress/expected/join_1.out b/src/test/regress/expected/join_1.out
index 725cbee2677..289ccb6c9f7 100644
--- a/src/test/regress/expected/join_1.out
+++ b/src/test/regress/expected/join_1.out
@@ -1846,10 +1846,6 @@ SELECT '' AS "xxx", *
 --
 -- More complicated constructs
 --
--- UNION JOIN isn't implemented yet
-SELECT '' AS "xxx", *
-  FROM J1_TBL UNION JOIN J2_TBL;
-ERROR:  UNION JOIN is not implemented
 --
 -- Multiway full join
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index a5e521e714a..ffc2afe6ed4 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -198,10 +198,6 @@ SELECT '' AS "xxx", *
 -- More complicated constructs
 --
 
--- UNION JOIN isn't implemented yet
-SELECT '' AS "xxx", *
-  FROM J1_TBL UNION JOIN J2_TBL;
-
 --
 -- Multiway full join
 --
-- 
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