Get rid of adjust_appendrel_attr_needed(), which has been broken ever since

we extended the appendrel mechanism to support UNION ALL optimization.  The
reason nobody noticed was that we are not actually using attr_needed data for
appendrel children; hence it seems more reasonable to rip it out than fix it.
Back-patch to 8.2 because an Assert failure is possible in corner cases.
Per examination of an example from Jim Nasby.

In HEAD, also get rid of AppendRelInfo.col_mappings, which is quite inadequate
to represent UNION ALL situations; depend entirely on translated_vars instead.

diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 0e5abc34930f4720f9661c9ac8c219275bdb56e3..8187ab37d5b0e3a310bf1fbd816b731d63bf66f9 100644 (file)
--- a/src/backend/optimizer/path/allpaths.c
+++ b/src/backend/optimizer/path/allpaths.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.168.2.2 2008/04/01 00:48:44 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.168.2.3 2008/11/11 18:13:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -351,14 +351,12 @@ set_append_rel_pathlist(PlannerInfo *root, RelOptInfo *rel,
                }
 
                /*
-                * Copy the parent's attr_needed data as well, with appropriate
-                * adjustment of relids and attribute numbers.
+                * Note: we could compute appropriate attr_needed data for the
+                * child's variables, by transforming the parent's attr_needed
+                * through the translated_vars mapping.  However, currently there's
+                * no need because attr_needed is only examined for base relations
+                * not otherrels.  So we just leave the child's attr_needed empty.
                 */
-               pfree(childrel->attr_needed);
-               childrel->attr_needed =
-                       adjust_appendrel_attr_needed(rel, appinfo,
-                                                                                childrel->min_attr,
-                                                                                childrel->max_attr);
 
                /*
                 * Compute the child's access paths, and add the cheapest one to the

diff --git a/src/backend/optimizer/prep/prepunion.c b/src/backend/optimizer/prep/prepunion.c
index 351d76d0fda9c17b14e80ee4dfda32b128af349b..2779da74d0aa250be782f5f19388f7f2271b9b7c 100644 (file)
--- a/src/backend/optimizer/prep/prepunion.c
+++ b/src/backend/optimizer/prep/prepunion.c
@@ -22,7 +22,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.146 2008/01/01 19:45:50 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/prep/prepunion.c,v 1.146.2.1 2008/11/11 18:13:43 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1259,70 +1259,6 @@ adjust_relid_set(Relids relids, Index oldrelid, Index newrelid)
        return relids;
 }
 
-/*
- * adjust_appendrel_attr_needed
- *             Adjust an attr_needed[] array to reference a member rel instead of
- *             the original appendrel
- *
- * oldrel: source of data (we use the attr_needed, min_attr, max_attr fields)
- * appinfo: supplies parent_relid, child_relid, col_mappings
- * new_min_attr, new_max_attr: desired bounds of new attr_needed array
- *
- * The relid sets are adjusted by substituting child_relid for parent_relid.
- * (NOTE: oldrel is not necessarily the parent_relid relation!)  We are also
- * careful to map attribute numbers within the array properly. User
- * attributes have to be mapped through col_mappings, but system attributes
- * and whole-row references always have the same attno.
- *
- * Returns a palloc'd array with the specified bounds
- */
-Relids *
-adjust_appendrel_attr_needed(RelOptInfo *oldrel, AppendRelInfo *appinfo,
-                                                        AttrNumber new_min_attr, AttrNumber new_max_attr)
-{
-       Relids     *new_attr_needed;
-       Index           parent_relid = appinfo->parent_relid;
-       Index           child_relid = appinfo->child_relid;
-       int                     parent_attr;
-       ListCell   *lm;
-
-       /* Create empty result array */
-       new_attr_needed = (Relids *)
-               palloc0((new_max_attr - new_min_attr + 1) * sizeof(Relids));
-       /* Process user attributes, with appropriate attno mapping */
-       parent_attr = 1;
-       foreach(lm, appinfo->col_mappings)
-       {
-               int                     child_attr = lfirst_int(lm);
-
-               if (child_attr > 0)
-               {
-                       Relids          attrneeded;
-
-                       Assert(parent_attr <= oldrel->max_attr);
-                       Assert(child_attr <= new_max_attr);
-                       attrneeded = oldrel->attr_needed[parent_attr - oldrel->min_attr];
-                       attrneeded = adjust_relid_set(attrneeded,
-                                                                                 parent_relid, child_relid);
-                       new_attr_needed[child_attr - new_min_attr] = attrneeded;
-               }
-               parent_attr++;
-       }
-       /* Process system attributes, including whole-row references */
-       Assert(new_min_attr <= oldrel->min_attr);
-       for (parent_attr = oldrel->min_attr; parent_attr <= 0; parent_attr++)
-       {
-               Relids          attrneeded;
-
-               attrneeded = oldrel->attr_needed[parent_attr - oldrel->min_attr];
-               attrneeded = adjust_relid_set(attrneeded,
-                                                                         parent_relid, child_relid);
-               new_attr_needed[parent_attr - new_min_attr] = attrneeded;
-       }
-
-       return new_attr_needed;
-}
-
 /*
  * Adjust the targetlist entries of an inherited UPDATE operation
  *

diff --git a/src/include/optimizer/prep.h b/src/include/optimizer/prep.h
index b98040a498afd8a6b8cb0d78e48174001d17dc38..29b0846308b60320be0c5f849899a3f8a8c479bd 100644 (file)
--- a/src/include/optimizer/prep.h
+++ b/src/include/optimizer/prep.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/prep.h,v 1.59 2008/01/01 19:45:58 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/prep.h,v 1.59.2.1 2008/11/11 18:13:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -50,9 +50,4 @@ extern void expand_inherited_tables(PlannerInfo *root);
 
 extern Node *adjust_appendrel_attrs(Node *node, AppendRelInfo *appinfo);
 
-extern Relids *adjust_appendrel_attr_needed(RelOptInfo *oldrel,
-                                                        AppendRelInfo *appinfo,
-                                                        AttrNumber new_min_attr,
-                                                        AttrNumber new_max_attr);
-
 #endif   /* PREP_H */