Reimplementation of UNION/INTERSECT/EXCEPT. INTERSECT/EXCEPT now meet the

SQL92 semantics, including support for ALL option.  All three can be used
in subqueries and views.  DISTINCT and ORDER BY work now in views, too.
This rewrite fixes many problems with cross-datatype UNIONs and INSERT/SELECT
where the SELECT yields different datatypes than the INSERT needs.  I did
that by making UNION subqueries and SELECT in INSERT be treated like
subselects-in-FROM, thereby allowing an extra level of targetlist where the
datatype conversions can be inserted safely.
INITDB NEEDED!

1 files changed, 51 insertions, 28 deletions

diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index ab805406eca..41309426e8b 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2000, PostgreSQL, Inc
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parsenodes.h,v 1.114 2000/09/29 18:21:38 tgl Exp $
+ * $Id: parsenodes.h,v 1.115 2000/10/05 19:11:36 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -29,7 +29,6 @@
  *
  * we need the isPortal flag because portal names can be null too; can
  * get rid of it if we support CURSOR as a commandType.
- *
  */
 typedef struct Query
 {
@@ -45,33 +44,32 @@ typedef struct Query
 	bool		isPortal;		/* is this a retrieve into portal? */
 	bool		isBinary;		/* binary portal? */
 	bool		isTemp;			/* is 'into' a temp table? */
-	bool		unionall;		/* union without unique sort */
+
 	bool		hasAggs;		/* has aggregates in tlist or havingQual */
 	bool		hasSubLinks;	/* has subquery SubLink */
 
 	List	   *rtable;			/* list of range table entries */
 	FromExpr   *jointree;		/* table join tree (FROM and WHERE clauses) */
 
-	List	   *targetList;		/* target list (of TargetEntry) */
-
 	List	   *rowMarks;		/* integer list of RT indexes of relations
 								 * that are selected FOR UPDATE */
 
-	List	   *distinctClause; /* a list of SortClause's */
-
-	List	   *sortClause;		/* a list of SortClause's */
+	List	   *targetList;		/* target list (of TargetEntry) */
 
 	List	   *groupClause;	/* a list of GroupClause's */
 
 	Node	   *havingQual;		/* qualifications applied to groups */
 
-	List	   *intersectClause;
-	List	   *unionClause;	/* unions are linked under the previous
-								 * query */
+	List	   *distinctClause; /* a list of SortClause's */
+
+	List	   *sortClause;		/* a list of SortClause's */
 
 	Node	   *limitOffset;	/* # of result tuples to skip */
 	Node	   *limitCount;		/* # of result tuples to return */
 
+	Node	   *setOperations;	/* set-operation tree if this is top level
+								 * of a UNION/INTERSECT/EXCEPT query */
+
 	/* internal to planner */
 	List	   *base_rel_list;	/* list of base-relation RelOptInfos */
 	List	   *join_rel_list;	/* list of join-relation RelOptInfos */
@@ -785,19 +783,14 @@ typedef struct InsertStmt
 {
 	NodeTag		type;
 	char	   *relname;		/* relation to insert into */
-	List	   *distinctClause; /* NULL, list of DISTINCT ON exprs, or
-								 * lcons(NIL,NIL) for all (SELECT
-								 * DISTINCT) */
-	List	   *cols;			/* names of the columns */
+	List	   *cols;			/* optional: names of the target columns */
+	/*
+	 * An INSERT statement has *either* VALUES or SELECT, never both.
+	 * If VALUES, a targetList is supplied (empty for DEFAULT VALUES).
+	 * If SELECT, a complete SelectStmt (or SetOperation tree) is supplied.
+	 */
 	List	   *targetList;		/* the target list (of ResTarget) */
-	List	   *fromClause;		/* the from clause */
-	Node	   *whereClause;	/* qualifications */
-	List	   *groupClause;	/* GROUP BY clauses */
-	Node	   *havingClause;	/* having conditional-expression */
-	List	   *unionClause;	/* union subselect parameters */
-	bool		unionall;		/* union without unique sort */
-	List	   *intersectClause;
-	List	   *forUpdate;		/* FOR UPDATE clause */
+	Node	   *selectStmt;		/* the source SELECT */
 } InsertStmt;
 
 /* ----------------------
@@ -842,20 +835,50 @@ typedef struct SelectStmt
 	Node	   *whereClause;	/* qualifications */
 	List	   *groupClause;	/* GROUP BY clauses */
 	Node	   *havingClause;	/* having conditional-expression */
-	List	   *intersectClause;
-	List	   *exceptClause;
-
-	List	   *unionClause;	/* union subselect parameters */
 	List	   *sortClause;		/* sort clause (a list of SortGroupBy's) */
 	char	   *portalname;		/* the portal (cursor) to create */
 	bool		binary;			/* a binary (internal) portal? */
 	bool		istemp;			/* into is a temp table */
-	bool		unionall;		/* union without unique sort */
 	Node	   *limitOffset;	/* # of result tuples to skip */
 	Node	   *limitCount;		/* # of result tuples to return */
 	List	   *forUpdate;		/* FOR UPDATE clause */
 } SelectStmt;
 
+/* ----------------------
+ *		Select Statement with Set Operations
+ *
+ * UNION/INTERSECT/EXCEPT operations are represented in the output of gram.y
+ * as a tree whose leaves are SelectStmts and internal nodes are
+ * SetOperationStmts.  The statement-wide info (ORDER BY, etc clauses)
+ * is placed in the leftmost SelectStmt leaf.
+ *
+ * After parse analysis, there is a top-level Query node containing the leaf
+ * SELECTs as subqueries in its range table.  Its setOperations field is the
+ * SetOperationStmt tree with leaf SelectStmt nodes replaced by RangeTblRef
+ * nodes.  The statement-wide options such as ORDER BY are attached to this
+ * top-level Query.
+ * ----------------------
+ */
+typedef enum SetOperation
+{
+	SETOP_UNION,
+	SETOP_INTERSECT,
+	SETOP_EXCEPT
+} SetOperation;
+
+typedef struct SetOperationStmt
+{
+	NodeTag		type;
+	SetOperation op;			/* type of set op */
+	bool		all;			/* ALL specified? */
+	Node	   *larg;			/* left child */
+	Node	   *rarg;			/* right child */
+	/* Eventually add fields for CORRESPONDING spec here */
+
+	/* This field is filled in during parse analysis: */
+	List	   *colTypes;		/* integer list of OIDs of output column types */
+} SetOperationStmt;
+
 /****************************************************************************
  *	Supporting data structures for Parse Trees
  *