Fix WITH attached to a nested set operation (UNION/INTERSECT/EXCEPT).

Parse analysis neglected to cover the case of a WITH clause attached to an
intermediate-level set operation; it only handled WITH at the top level
or WITH attached to a leaf-level SELECT.  Per report from Adam Mackler.

In HEAD, I rearranged the order of SelectStmt's fields to put withClause
with the other fields that can appear on non-leaf SelectStmts.  In back
branches, leave it alone to avoid a possible ABI break for third-party
code.

Back-patch to 8.4 where WITH support was added.

diff --git a/src/backend/parser/analyze.c b/src/backend/parser/analyze.c
index bfd3ab941a771ac8a994afc72967fb61c3321120..263edb5a7a61d3a3c2ea5f1a5f9a255024d86bad 100644 (file)
--- a/src/backend/parser/analyze.c
+++ b/src/backend/parser/analyze.c
@@ -1322,6 +1322,7 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
        Node       *limitOffset;
        Node       *limitCount;
        List       *lockingClause;
+       WithClause *withClause;
        Node       *node;
        ListCell   *left_tlist,
                           *lct,
@@ -1338,14 +1339,6 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
 
        qry->commandType = CMD_SELECT;
 
-       /* process the WITH clause independently of all else */
-       if (stmt->withClause)
-       {
-               qry->hasRecursive = stmt->withClause->recursive;
-               qry->cteList = transformWithClause(pstate, stmt->withClause);
-               qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
-       }
-
        /*
         * Find leftmost leaf SelectStmt.  We currently only need to do this in
         * order to deliver a suitable error message if there's an INTO clause
@@ -1375,11 +1368,13 @@ transformSetOperationStmt(ParseState *pstate, SelectStmt *stmt)
        limitOffset = stmt->limitOffset;
        limitCount = stmt->limitCount;
        lockingClause = stmt->lockingClause;
+       withClause = stmt->withClause;
 
        stmt->sortClause = NIL;
        stmt->limitOffset = NULL;
        stmt->limitCount = NULL;
        stmt->lockingClause = NIL;
+       stmt->withClause = NULL;
 
        /* We don't support FOR UPDATE/SHARE with set ops at the moment. */
        if (lockingClause)
@@ -1387,6 +1382,14 @@ 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 independently of all else */
+       if (withClause)
+       {
+               qry->hasRecursive = withClause->recursive;
+               qry->cteList = transformWithClause(pstate, withClause);
+               qry->hasModifyingCTE = pstate->p_hasModifyingCTE;
+       }
+
        /*
         * Recursively transform the components of the tree.
         */
@@ -1572,10 +1575,10 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
                                 errmsg("SELECT FOR UPDATE/SHARE is not allowed with UNION/INTERSECT/EXCEPT")));
 
        /*
-        * If an internal node of a set-op tree has ORDER BY, LIMIT, or FOR UPDATE
-        * clauses attached, we need to treat it like a leaf node to generate an
-        * independent sub-Query tree.  Otherwise, it can be represented by a
-        * SetOperationStmt node underneath the parent Query.
+        * If an internal node of a set-op tree has ORDER BY, LIMIT, FOR UPDATE,
+        * or WITH clauses attached, we need to treat it like a leaf node to
+        * generate an independent sub-Query tree.  Otherwise, it can be
+        * represented by a SetOperationStmt node underneath the parent Query.
         */
        if (stmt->op == SETOP_NONE)
        {
@@ -1586,7 +1589,7 @@ transformSetOperationTree(ParseState *pstate, SelectStmt *stmt,
        {
                Assert(stmt->larg != NULL && stmt->rarg != NULL);
                if (stmt->sortClause || stmt->limitOffset || stmt->limitCount ||
-                       stmt->lockingClause)
+                       stmt->lockingClause || stmt->withClause)
                        isLeaf = true;
                else
                        isLeaf = false;

diff --git a/src/backend/parser/parse_cte.c b/src/backend/parser/parse_cte.c
index 2a7d4cd07244054a9e3cea3554712eb133662384..d04fb6dec1491a6f01f428171550846645005884 100644 (file)
--- a/src/backend/parser/parse_cte.c
+++ b/src/backend/parser/parse_cte.c
@@ -678,6 +678,18 @@ checkWellFormedRecursion(CteState *cstate)
                if (cstate->selfrefcount != 1)  /* shouldn't happen */
                        elog(ERROR, "missing recursive reference");
 
+               /* WITH mustn't contain self-reference, either */
+               if (stmt->withClause)
+               {
+                       cstate->curitem = i;
+                       cstate->innerwiths = NIL;
+                       cstate->selfrefcount = 0;
+                       cstate->context = RECURSION_SUBLINK;
+                       checkWellFormedRecursionWalker((Node *) stmt->withClause->ctes,
+                                                                                  cstate);
+                       Assert(cstate->innerwiths == NIL);
+               }
+
                /*
                 * Disallow ORDER BY and similar decoration atop the UNION. These
                 * don't make sense because it's impossible to figure out what they
@@ -933,7 +945,7 @@ checkWellFormedSelectStmt(SelectStmt *stmt, CteState *cstate)
                                                                                           cstate);
                                checkWellFormedRecursionWalker((Node *) stmt->lockingClause,
                                                                                           cstate);
-                               break;
+                               /* stmt->withClause is intentionally ignored here */
                                break;
                        case SETOP_EXCEPT:
                                if (stmt->all)
@@ -952,6 +964,7 @@ checkWellFormedSelectStmt(SelectStmt *stmt, CteState *cstate)
                                                                                           cstate);
                                checkWellFormedRecursionWalker((Node *) stmt->lockingClause,
                                                                                           cstate);
+                               /* stmt->withClause is intentionally ignored here */
                                break;
                        default:
                                elog(ERROR, "unrecognized set op: %d",

diff --git a/src/test/regress/expected/with.out b/src/test/regress/expected/with.out
index 57e178afa945e51cd04f24e50eda696a595093af..c83400384e7eb61f7cd2c9a5f8aa18c74c26c483 100644 (file)
--- a/src/test/regress/expected/with.out
+++ b/src/test/regress/expected/with.out
@@ -1160,6 +1160,57 @@ SELECT * FROM t;
  10
 (55 rows)
 
+--
+-- test WITH attached to intermediate-level set operation
+--
+WITH outermost(x) AS (
+  SELECT 1
+  UNION (WITH innermost as (SELECT 2)
+         SELECT * FROM innermost
+         UNION SELECT 3)
+)
+SELECT * FROM outermost;
+ x 
+---
+ 1
+ 2
+ 3
+(3 rows)
+
+WITH outermost(x) AS (
+  SELECT 1
+  UNION (WITH innermost as (SELECT 2)
+         SELECT * FROM outermost  -- fail
+         UNION SELECT * FROM innermost)
+)
+SELECT * FROM outermost;
+ERROR:  relation "outermost" does not exist
+LINE 4:          SELECT * FROM outermost  
+                               ^
+DETAIL:  There is a WITH item named "outermost", but it cannot be referenced from this part of the query.
+HINT:  Use WITH RECURSIVE, or re-order the WITH items to remove forward references.
+WITH RECURSIVE outermost(x) AS (
+  SELECT 1
+  UNION (WITH innermost as (SELECT 2)
+         SELECT * FROM outermost
+         UNION SELECT * FROM innermost)
+)
+SELECT * FROM outermost;
+ x 
+---
+ 1
+ 2
+(2 rows)
+
+WITH RECURSIVE outermost(x) AS (
+  WITH innermost as (SELECT 2 FROM outermost) -- fail
+    SELECT * FROM innermost
+    UNION SELECT * from outermost
+)
+SELECT * FROM outermost;
+ERROR:  recursive reference to query "outermost" must not appear within a subquery
+LINE 2:   WITH innermost as (SELECT 2 FROM outermost) 
+                                           ^
 --
 -- Data-modifying statements in WITH
 --

diff --git a/src/test/regress/sql/with.sql b/src/test/regress/sql/with.sql
index 9c6732b961190b114ff6ca4e66acee9c2a9f30f2..22fdddc4eeafa2de36c1eaf57b20ec0d44d27df3 100644 (file)
--- a/src/test/regress/sql/with.sql
+++ b/src/test/regress/sql/with.sql
@@ -539,6 +539,41 @@ WITH RECURSIVE t(j) AS (
 )
 SELECT * FROM t;
 
+--
+-- test WITH attached to intermediate-level set operation
+--
+
+WITH outermost(x) AS (
+  SELECT 1
+  UNION (WITH innermost as (SELECT 2)
+         SELECT * FROM innermost
+         UNION SELECT 3)
+)
+SELECT * FROM outermost;
+
+WITH outermost(x) AS (
+  SELECT 1
+  UNION (WITH innermost as (SELECT 2)
+         SELECT * FROM outermost  -- fail
+         UNION SELECT * FROM innermost)
+)
+SELECT * FROM outermost;
+
+WITH RECURSIVE outermost(x) AS (
+  SELECT 1
+  UNION (WITH innermost as (SELECT 2)
+         SELECT * FROM outermost
+         UNION SELECT * FROM innermost)
+)
+SELECT * FROM outermost;
+
+WITH RECURSIVE outermost(x) AS (
+  WITH innermost as (SELECT 2 FROM outermost) -- fail
+    SELECT * FROM innermost
+    UNION SELECT * from outermost
+)
+SELECT * FROM outermost;
+
 --
 -- Data-modifying statements in WITH
 --