Make flatten_join_alias_vars() do the right thing when expanding an alias

referenced from a subquery.  Per example from Stefanos Harhalakis.

diff --git a/src/backend/optimizer/util/var.c b/src/backend/optimizer/util/var.c
index 729ded513234eb68135404dde587dedb9e648605..4fad46889fd08a0910cdc678398daa127c00b9ea 100644 (file)
--- a/src/backend/optimizer/util/var.c
+++ b/src/backend/optimizer/util/var.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.47 2003/01/20 18:54:58 tgl Exp $
+ *   $Header: /cvsroot/pgsql/src/backend/optimizer/util/var.c,v 1.48 2003/02/06 22:21:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -19,6 +19,7 @@
 #include "optimizer/prep.h"
 #include "optimizer/var.h"
 #include "parser/parsetree.h"
+#include "rewrite/rewriteManip.h"
 
 
 typedef struct
@@ -400,14 +401,25 @@ flatten_join_alias_vars_mutator(Node *node,
        RangeTblEntry *rte;
        Node       *newvar;
 
+       /* No change unless Var belongs to a JOIN of the target level */
        if (var->varlevelsup != context->sublevels_up)
            return node;        /* no need to copy, really */
        rte = rt_fetch(var->varno, context->root->rtable);
        if (rte->rtekind != RTE_JOIN)
            return node;
        Assert(var->varattno > 0);
+       /* Okay, must expand it */
        newvar = (Node *) nth(var->varattno - 1, rte->joinaliasvars);
-       /* expand it; recurse in case join input is itself a join */
+       /*
+        * If we are expanding an alias carried down from an upper query,
+        * must adjust its varlevelsup fields.
+        */
+       if (context->sublevels_up != 0)
+       {
+           newvar = copyObject(newvar);
+           IncrementVarSublevelsUp(newvar, context->sublevels_up, 0);
+       }
+       /* Recurse in case join input is itself a join */
        return flatten_join_alias_vars_mutator(newvar, context);
    }
    if (IsA(node, InClauseInfo))