Implement SQL-standard WITH clauses, including WITH RECURSIVE.

There are some unimplemented aspects: recursive queries must use UNION ALL
(should allow UNION too), and we don't have SEARCH or CYCLE clauses.
These might or might not get done for 8.4, but even without them it's a
pretty useful feature.

There are also a couple of small loose ends and definitional quibbles,
which I'll send a memo about to pgsql-hackers shortly.  But let's land
the patch now so we can get on with other development.

Yoshiyuki Asaba, with lots of help from Tatsuo Ishii and Tom Lane

1 files changed, 98 insertions, 9 deletions

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index 18585b860b4..8934c04bb24 100644
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -17,7 +17,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.379 2008/09/01 20:42:44 tgl Exp $
+ *	$PostgreSQL: pgsql/src/backend/parser/analyze.c,v 1.380 2008/10/04 21:56:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -32,6 +32,7 @@
 #include "parser/parse_agg.h"
 #include "parser/parse_clause.h"
 #include "parser/parse_coerce.h"
+#include "parser/parse_cte.h"
 #include "parser/parse_oper.h"
 #include "parser/parse_relation.h"
 #include "parser/parse_target.h"
@@ -309,6 +310,8 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		pstate->p_relnamespace = NIL;
 		sub_varnamespace = pstate->p_varnamespace;
 		pstate->p_varnamespace = NIL;
+		/* There can't be any outer WITH to worry about */
+		Assert(pstate->p_ctenamespace == NIL);
 	}
 	else
 	{
@@ -447,6 +450,13 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 		List	   *exprsLists = NIL;
 		int			sublist_length = -1;
 
+		/* process the WITH clause */
+		if (selectStmt->withClause)
+		{
+			qry->hasRecursive = selectStmt->withClause->recursive;
+			qry->cteList = transformWithClause(pstate, selectStmt->withClause);
+		}
+
 		foreach(lc, selectStmt->valuesLists)
 		{
 			List	   *sublist = (List *) lfirst(lc);
@@ -540,6 +550,13 @@ transformInsertStmt(ParseState *pstate, InsertStmt *stmt)
 
 		Assert(list_length(valuesLists) == 1);
 
+		/* process the WITH clause */
+		if (selectStmt->withClause)
+		{
+			qry->hasRecursive = selectStmt->withClause->recursive;
+			qry->cteList = transformWithClause(pstate, selectStmt->withClause);
+		}
+
 		/* Do basic expression transformation (same as a ROW() expr) */
 		exprList = transformExpressionList(pstate,
 										   (List *) linitial(valuesLists));
@@ -694,6 +711,13 @@ transformSelectStmt(ParseState *pstate, SelectStmt *stmt)
 	/* make FOR UPDATE/FOR SHARE info available to addRangeTableEntry */
 	pstate->p_locking_clause = stmt->lockingClause;
 
+	/* process the WITH clause */
+	if (stmt->withClause)
+	{
+		qry->hasRecursive = stmt->withClause->recursive;
+		qry->cteList = transformWithClause(pstate, stmt->withClause);
+	}
+
 	/* process the FROM clause */
 	transformFromClause(pstate, stmt->fromClause);
 
@@ -814,6 +838,13 @@ transformValuesClause(ParseState *pstate, SelectStmt *stmt)
 	Assert(stmt->havingClause == NULL);
 	Assert(stmt->op == SETOP_NONE);
 
+	/* process the WITH clause */
+	if (stmt->withClause)
+	{
+		qry->hasRecursive = stmt->withClause->recursive;
+		qry->cteList = transformWithClause(pstate, stmt->withClause);
+	}
+
 	/*
 	 * For each row of VALUES, transform the raw expressions and gather type
 	 * information.  This is also a handy place to reject DEFAULT nodes, which
@@ -1059,6 +1090,13 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
 				 errmsg("SELECT FOR UPDATE/SHARE is not allowed with UNION/INTERSECT/EXCEPT")));
 
+	/* process the WITH clause */
+	if (stmt->withClause)
+	{
+		qry->hasRecursive = stmt->withClause->recursive;
+		qry->cteList = transformWithClause(pstate, stmt->withClause);
+	}
+
 	/*
 	 * Recursively transform the components of the tree.
 	 */
@@ -1101,21 +1139,22 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 		TargetEntry *lefttle = (TargetEntry *) lfirst(left_tlist);
 		char	   *colName;
 		TargetEntry *tle;
-		Expr	   *expr;
+		Var		   *var;
 
 		Assert(!lefttle->resjunk);
 		colName = pstrdup(lefttle->resname);
-		expr = (Expr *) makeVar(leftmostRTI,
-								lefttle->resno,
-								colType,
-								colTypmod,
-								0);
-		tle = makeTargetEntry(expr,
+		var = makeVar(leftmostRTI,
+					  lefttle->resno,
+					  colType,
+					  colTypmod,
+					  0);
+		var->location = exprLocation((Node *) lefttle->expr);
+		tle = makeTargetEntry((Expr *) var,
 							  (AttrNumber) pstate->p_next_resno++,
 							  colName,
 							  false);
 		qry->targetList = lappend(qry->targetList, tle);
-		targetvars = lappend(targetvars, expr);
+		targetvars = lappend(targetvars, var);
 		targetnames = lappend(targetnames, makeString(colName));
 		left_tlist = lnext(left_tlist);
 	}
@@ -1841,6 +1880,30 @@ transformLockingClause(ParseState *pstate, Query *qry, LockingClause *lc)
 					 */
 					transformLockingClause(pstate, rte->subquery, allrels);
 					break;
+				case RTE_CTE:
+					{
+						/*
+						 * We allow FOR UPDATE/SHARE of a WITH query to be
+						 * propagated into the WITH, but it doesn't seem
+						 * very sane to allow this for a reference to an
+						 * outer-level WITH.  And it definitely wouldn't
+						 * work for a self-reference, since we're not done
+						 * analyzing the CTE anyway.
+						 */
+						CommonTableExpr *cte;
+
+						if (rte->ctelevelsup > 0 || rte->self_reference)
+							ereport(ERROR,
+									(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+									 errmsg("SELECT FOR UPDATE/SHARE cannot be applied to an outer-level WITH query")));
+						cte = GetCTEForRTE(pstate, rte);
+						/* should be analyzed by now */
+						Assert(IsA(cte->ctequery, Query));
+						transformLockingClause(pstate,
+											   (Query *) cte->ctequery,
+											   allrels);
+					}
+					break;
 				default:
 					/* ignore JOIN, SPECIAL, FUNCTION RTEs */
 					break;
@@ -1908,6 +1971,32 @@ transformLockingClause(ParseState *pstate, Query *qry, LockingClause *lc)
 									 errmsg("SELECT FOR UPDATE/SHARE cannot be applied to VALUES"),
 									 parser_errposition(pstate, thisrel->location)));
 							break;
+						case RTE_CTE:
+							{
+								/*
+								 * We allow FOR UPDATE/SHARE of a WITH query
+								 * to be propagated into the WITH, but it
+								 * doesn't seem very sane to allow this for a
+								 * reference to an outer-level WITH.  And it
+								 * definitely wouldn't work for a
+								 * self-reference, since we're not done
+								 * analyzing the CTE anyway.
+								 */
+								CommonTableExpr *cte;
+
+								if (rte->ctelevelsup > 0 || rte->self_reference)
+									ereport(ERROR,
+											(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+											 errmsg("SELECT FOR UPDATE/SHARE cannot be applied to an outer-level WITH query"),
+											 parser_errposition(pstate, thisrel->location)));
+								cte = GetCTEForRTE(pstate, rte);
+								/* should be analyzed by now */
+								Assert(IsA(cte->ctequery, Query));
+								transformLockingClause(pstate,
+													   (Query *) cte->ctequery,
+													   allrels);
+							}
+							break;
 						default:
 							elog(ERROR, "unrecognized RTE type: %d",
 								 (int) rte->rtekind);