Fix brokenness of nested EXCEPT/INTERSECT queries. prepunion was being

a tad sloppy about generating the targetlist for some nodes, by generating
a tlist entry that claimed to be a constant when the value wasn't actually
constant.  This caused setrefs.c to do the wrong thing later on.

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 764fe1836c64d052edac896c4db3258ca09ebcd5..dbbe004aef20ded3cb5ef700762529cb6668f4ac 100644 (file)
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -14,7 +14,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.65 2001/06/05 05:26:04 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/prep/prepunion.c,v 1.66 2001/08/14 17:12:57 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -275,12 +275,14 @@ generate_nonunion_plan(SetOperationStmt *op, Query *parse,
     *
     * The tlist for an Append plan isn't important as far as the Append is
     * concerned, but we must make it look real anyway for the benefit of
-    * the next plan level up.
+    * the next plan level up.  In fact, it has to be real enough that the
+    * flag column is shown as a variable not a constant, else setrefs.c
+    * will get confused.
     */
    plan = (Plan *)
        make_append(makeList2(lplan, rplan),
                    false,
-                   generate_setop_tlist(op->colTypes, 0, false,
+                   generate_setop_tlist(op->colTypes, 2, false,
                                         lplan->targetlist,
                                         refnames_tlist));
 
@@ -353,6 +355,13 @@ recurse_union_children(Node *setOp, Query *parse,
 
 /*
  * Generate targetlist for a set-operation plan node
+ *
+ * colTypes: column datatypes for non-junk columns
+ * flag: -1 if no flag column needed, 0 or 1 to create a const flag column,
+ *       2 to create a variable flag column
+ * hack_constants: true to copy up constants (see comments in code)
+ * input_tlist: targetlist of this node's input node
+ * refnames_tlist: targetlist to take column names from
  */
 static List *
 generate_setop_tlist(List *colTypes, int flag,
@@ -414,19 +423,32 @@ generate_setop_tlist(List *colTypes, int flag,
 
    if (flag >= 0)
    {
-       /* Add a resjunk column yielding specified flag value */
+       /* Add a resjunk flag column */
        resdom = makeResdom((AttrNumber) resno++,
                            INT4OID,
                            -1,
                            pstrdup("flag"),
                            true);
-       expr = (Node *) makeConst(INT4OID,
-                                 sizeof(int4),
-                                 Int32GetDatum(flag),
-                                 false,
-                                 true,
-                                 false,
-                                 false);
+       if (flag <= 1)
+       {
+           /* flag value is the given constant */
+           expr = (Node *) makeConst(INT4OID,
+                                     sizeof(int4),
+                                     Int32GetDatum(flag),
+                                     false,
+                                     true,
+                                     false,
+                                     false);
+       }
+       else
+       {
+           /* flag value is being copied up from subplan */
+           expr = (Node *) makeVar(0,
+                                   resdom->resno,
+                                   INT4OID,
+                                   -1,
+                                   0);
+       }
        tlist = lappend(tlist, makeTargetEntry(resdom, expr));
    }