Fix EquivalenceClass code to handle volatile sort expressions in a more
authorTom Lane
Thu, 8 Nov 2007 21:49:48 +0000 (21:49 +0000)
committerTom Lane
Thu, 8 Nov 2007 21:49:48 +0000 (21:49 +0000)
predictable manner; in particular that if you say ORDER BY output-column-ref,
it will in fact sort by that specific column even if there are multiple
syntactic matches.  An example is
SELECT random() AS a, random() AS b FROM ... ORDER BY b, a;
While the use-case for this might be a bit debatable, it worked as expected
in earlier releases, so we should preserve the behavior for 8.3.  Per my
recent proposal.

While at it, fix convert_subquery_pathkeys() to handle RelabelType stripping
in both directions; it needs this for the same reasons make_sort_from_pathkeys
does.

src/backend/nodes/outfuncs.c
src/backend/optimizer/path/equivclass.c
src/backend/optimizer/path/pathkeys.c
src/backend/optimizer/plan/createplan.c
src/backend/optimizer/util/tlist.c
src/include/nodes/relation.h
src/include/optimizer/paths.h
src/include/optimizer/tlist.h

index 005879b8c910e5ef892dacd09612719045e5a87d..fc4f7d2dacac86307f461ccf438048540d3c7a72 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.315 2007/10/11 18:05:27 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/nodes/outfuncs.c,v 1.316 2007/11/08 21:49:47 tgl Exp $
  *
  * NOTES
  *   Every node type that can appear in stored rules' parsetrees *must*
@@ -1405,6 +1405,7 @@ _outEquivalenceClass(StringInfo str, EquivalenceClass *node)
    WRITE_BOOL_FIELD(ec_has_volatile);
    WRITE_BOOL_FIELD(ec_below_outer_join);
    WRITE_BOOL_FIELD(ec_broken);
+   WRITE_UINT_FIELD(ec_sortref);
 }
 
 static void
index fc862438ffb011219d45430832fa840b060fd12c..18c6ff936864cc24edd453a1fa733211084e57f0 100644 (file)
@@ -10,7 +10,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.3 2007/07/07 20:46:45 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/optimizer/path/equivclass.c,v 1.4 2007/11/08 21:49:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -294,6 +294,7 @@ process_equivalence(PlannerInfo *root, RestrictInfo *restrictinfo,
        ec->ec_has_volatile = false;
        ec->ec_below_outer_join = below_outer_join;
        ec->ec_broken = false;
+       ec->ec_sortref = 0;
        ec->ec_merged = NULL;
        em1 = add_eq_member(ec, item1, item1_relids, false, item1_type);
        em2 = add_eq_member(ec, item2, item2_relids, false, item2_type);
@@ -354,6 +355,9 @@ add_eq_member(EquivalenceClass *ec, Expr *expr, Relids relids,
  *   class it is a member of; if none, build a new single-member
  *   EquivalenceClass for it.
  *
+ * sortref is the SortGroupRef of the originating SortClause, if any,
+ * or zero if not.
+ *
  * This can be used safely both before and after EquivalenceClass merging;
  * since it never causes merging it does not invalidate any existing ECs
  * or PathKeys.
@@ -367,7 +371,8 @@ EquivalenceClass *
 get_eclass_for_sort_expr(PlannerInfo *root,
                         Expr *expr,
                         Oid expr_datatype,
-                        List *opfamilies)
+                        List *opfamilies,
+                        Index sortref)
 {
    EquivalenceClass *newec;
    EquivalenceMember *newem;
@@ -382,7 +387,9 @@ get_eclass_for_sort_expr(PlannerInfo *root,
        EquivalenceClass *cur_ec = (EquivalenceClass *) lfirst(lc1);
        ListCell   *lc2;
 
-       /* we allow matching to a volatile EC here */
+       /* Never match to a volatile EC */
+       if (cur_ec->ec_has_volatile)
+           continue;
 
        if (!equal(opfamilies, cur_ec->ec_opfamilies))
            continue;
@@ -423,6 +430,7 @@ get_eclass_for_sort_expr(PlannerInfo *root,
    newec->ec_has_volatile = contain_volatile_functions((Node *) expr);
    newec->ec_below_outer_join = false;
    newec->ec_broken = false;
+   newec->ec_sortref = sortref;
    newec->ec_merged = NULL;
    newem = add_eq_member(newec, expr, pull_varnos((Node *) expr),
                          false, expr_datatype);
index f96d7bb5554a177f17e9f8e2982969007509380a..846fe78ee6cc5cd99acd56c02bb29aa695fab9f2 100644 (file)
@@ -11,7 +11,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.88 2007/11/08 19:25:37 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/optimizer/path/pathkeys.c,v 1.89 2007/11/08 21:49:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -46,6 +46,7 @@ static bool pathkey_is_redundant(PathKey *new_pathkey, List *pathkeys);
 static PathKey *make_pathkey_from_sortinfo(PlannerInfo *root,
                           Expr *expr, Oid ordering_op,
                           bool nulls_first,
+                          Index sortref,
                           bool canonicalize);
 static Var *find_indexkey_var(PlannerInfo *root, RelOptInfo *rel,
                  AttrNumber varattno);
@@ -233,6 +234,9 @@ canonicalize_pathkeys(PlannerInfo *root, List *pathkeys)
  *   a PathKey.  If canonicalize = true, the result is a "canonical"
  *   PathKey, otherwise not.  (But note it might be redundant anyway.)
  *
+ * If the PathKey is being generated from a SortClause, sortref should be
+ * the SortClause's SortGroupRef; otherwise zero.
+ *
  * canonicalize should always be TRUE after EquivalenceClass merging has
  * been performed, but FALSE if we haven't done EquivalenceClass merging yet.
  */
@@ -240,6 +244,7 @@ static PathKey *
 make_pathkey_from_sortinfo(PlannerInfo *root,
                           Expr *expr, Oid ordering_op,
                           bool nulls_first,
+                          Index sortref,
                           bool canonicalize)
 {
    Oid         opfamily,
@@ -303,7 +308,8 @@ make_pathkey_from_sortinfo(PlannerInfo *root,
    }
 
    /* Now find or create a matching EquivalenceClass */
-   eclass = get_eclass_for_sort_expr(root, expr, opcintype, opfamilies);
+   eclass = get_eclass_for_sort_expr(root, expr, opcintype, opfamilies,
+                                     sortref);
 
    /* And finally we can find or create a PathKey node */
    if (canonicalize)
@@ -525,6 +531,7 @@ build_index_pathkeys(PlannerInfo *root,
                                              indexkey,
                                              sortop,
                                              nulls_first,
+                                             0,
                                              true);
 
        /* Add to list unless redundant */
@@ -597,102 +604,161 @@ convert_subquery_pathkeys(PlannerInfo *root, RelOptInfo *rel,
        PathKey    *sub_pathkey = (PathKey *) lfirst(i);
        EquivalenceClass *sub_eclass = sub_pathkey->pk_eclass;
        PathKey    *best_pathkey = NULL;
-       int         best_score = -1;
-       ListCell   *j;
 
-       /*
-        * The sub_pathkey's EquivalenceClass could contain multiple elements
-        * (representing knowledge that multiple items are effectively equal).
-        * Each element might match none, one, or more of the output columns
-        * that are visible to the outer query. This means we may have
-        * multiple possible representations of the sub_pathkey in the context
-        * of the outer query.  Ideally we would generate them all and put
-        * them all into an EC of the outer query, thereby propagating
-        * equality knowledge up to the outer query.  Right now we cannot do
-        * so, because the outer query's EquivalenceClasses are already frozen
-        * when this is called. Instead we prefer the one that has the highest
-        * "score" (number of EC peers, plus one if it matches the outer
-        * query_pathkeys). This is the most likely to be useful in the outer
-        * query.
-        */
-       foreach(j, sub_eclass->ec_members)
+       if (sub_eclass->ec_has_volatile)
        {
-           EquivalenceMember *sub_member = (EquivalenceMember *) lfirst(j);
-           Expr       *sub_expr = sub_member->em_expr;
-           Expr       *rtarg;
-           ListCell   *k;
-
            /*
-            * We handle two cases: the sub_pathkey key can be either an exact
-            * match for a targetlist entry, or a RelabelType of a targetlist
-            * entry.  (The latter case is worth extra code because it arises
-            * frequently in connection with varchar fields.)
+            * If the sub_pathkey's EquivalenceClass is volatile, then it must
+            * have come from an ORDER BY clause, and we have to match it to
+            * that same targetlist entry.
             */
-           if (IsA(sub_expr, RelabelType))
-               rtarg = ((RelabelType *) sub_expr)->arg;
-           else
-               rtarg = NULL;
-
-           foreach(k, sub_tlist)
+           TargetEntry *tle;
+
+           if (sub_eclass->ec_sortref == 0)        /* can't happen */
+               elog(ERROR, "volatile EquivalenceClass has no sortref");
+           tle = get_sortgroupref_tle(sub_eclass->ec_sortref, sub_tlist);
+           Assert(tle);
+           /* resjunk items aren't visible to outer query */
+           if (!tle->resjunk)
            {
-               TargetEntry *tle = (TargetEntry *) lfirst(k);
+               /* We can represent this sub_pathkey */
+               EquivalenceMember *sub_member;
                Expr       *outer_expr;
                EquivalenceClass *outer_ec;
-               PathKey    *outer_pk;
-               int         score;
 
-               /* resjunk items aren't visible to outer query */
-               if (tle->resjunk)
-                   continue;
+               Assert(list_length(sub_eclass->ec_members) == 1);
+               sub_member = (EquivalenceMember *) linitial(sub_eclass->ec_members);
+               outer_expr = (Expr *)
+                   makeVar(rel->relid,
+                           tle->resno,
+                           exprType((Node *) tle->expr),
+                           exprTypmod((Node *) tle->expr),
+                           0);
+               outer_ec =
+                   get_eclass_for_sort_expr(root,
+                                            outer_expr,
+                                            sub_member->em_datatype,
+                                            sub_eclass->ec_opfamilies,
+                                            0);
+               best_pathkey =
+                   make_canonical_pathkey(root,
+                                          outer_ec,
+                                          sub_pathkey->pk_opfamily,
+                                          sub_pathkey->pk_strategy,
+                                          sub_pathkey->pk_nulls_first);
+           }
+       }
+       else
+       {
+           /*
+            * Otherwise, the sub_pathkey's EquivalenceClass could contain
+            * multiple elements (representing knowledge that multiple items
+            * are effectively equal).  Each element might match none, one, or
+            * more of the output columns that are visible to the outer
+            * query. This means we may have multiple possible representations
+            * of the sub_pathkey in the context of the outer query.  Ideally
+            * we would generate them all and put them all into an EC of the
+            * outer query, thereby propagating equality knowledge up to the
+            * outer query.  Right now we cannot do so, because the outer
+            * query's EquivalenceClasses are already frozen when this is
+            * called. Instead we prefer the one that has the highest "score"
+            * (number of EC peers, plus one if it matches the outer
+            * query_pathkeys). This is the most likely to be useful in the
+            * outer query.
+            */
+           int         best_score = -1;
+           ListCell   *j;
 
-               if (equal(tle->expr, sub_expr))
-               {
-                   /* Exact match */
-                   outer_expr = (Expr *)
-                       makeVar(rel->relid,
-                               tle->resno,
-                               exprType((Node *) tle->expr),
-                               exprTypmod((Node *) tle->expr),
-                               0);
-               }
-               else if (rtarg && equal(tle->expr, rtarg))
+           foreach(j, sub_eclass->ec_members)
+           {
+               EquivalenceMember *sub_member = (EquivalenceMember *) lfirst(j);
+               Expr       *sub_expr = sub_member->em_expr;
+               Expr       *sub_stripped;
+               ListCell   *k;
+
+               /*
+                * We handle two cases: the sub_pathkey key can be either an
+                * exact match for a targetlist entry, or it could match after
+                * stripping RelabelType nodes.  (We need that case since
+                * make_pathkey_from_sortinfo could add or remove RelabelType.)
+                */
+               sub_stripped = sub_expr;
+               while (sub_stripped && IsA(sub_stripped, RelabelType))
+                   sub_stripped = ((RelabelType *) sub_stripped)->arg;
+
+               foreach(k, sub_tlist)
                {
-                   /* Match after discarding RelabelType */
-                   outer_expr = (Expr *)
-                       makeVar(rel->relid,
-                               tle->resno,
-                               exprType((Node *) tle->expr),
-                               exprTypmod((Node *) tle->expr),
-                               0);
-                   outer_expr = (Expr *)
-                       makeRelabelType((Expr *) outer_expr,
-                                       ((RelabelType *) sub_expr)->resulttype,
-                                    ((RelabelType *) sub_expr)->resulttypmod,
-                                  ((RelabelType *) sub_expr)->relabelformat);
-               }
-               else
-                   continue;
+                   TargetEntry *tle = (TargetEntry *) lfirst(k);
+                   Expr       *outer_expr;
+                   EquivalenceClass *outer_ec;
+                   PathKey    *outer_pk;
+                   int         score;
 
-               /* Found a representation for this sub_pathkey */
-               outer_ec = get_eclass_for_sort_expr(root,
-                                                   outer_expr,
-                                                   sub_member->em_datatype,
-                                                   sub_eclass->ec_opfamilies);
-               outer_pk = make_canonical_pathkey(root,
-                                                 outer_ec,
-                                                 sub_pathkey->pk_opfamily,
-                                                 sub_pathkey->pk_strategy,
-                                                 sub_pathkey->pk_nulls_first);
-               /* score = # of equivalence peers */
-               score = list_length(outer_ec->ec_members) - 1;
-               /* +1 if it matches the proper query_pathkeys item */
-               if (retvallen < outer_query_keys &&
-                   list_nth(root->query_pathkeys, retvallen) == outer_pk)
-                   score++;
-               if (score > best_score)
-               {
-                   best_pathkey = outer_pk;
-                   best_score = score;
+                   /* resjunk items aren't visible to outer query */
+                   if (tle->resjunk)
+                       continue;
+
+                   if (equal(tle->expr, sub_expr))
+                   {
+                       /* Exact match */
+                       outer_expr = (Expr *)
+                           makeVar(rel->relid,
+                                   tle->resno,
+                                   exprType((Node *) tle->expr),
+                                   exprTypmod((Node *) tle->expr),
+                                   0);
+                   }
+                   else
+                   {
+                       Expr       *tle_stripped;
+
+                       tle_stripped = tle->expr;
+                       while (tle_stripped && IsA(tle_stripped, RelabelType))
+                           tle_stripped = ((RelabelType *) tle_stripped)->arg;
+
+                       if (equal(tle_stripped, sub_stripped))
+                       {
+                           /* Match after discarding RelabelType */
+                           outer_expr = (Expr *)
+                               makeVar(rel->relid,
+                                       tle->resno,
+                                       exprType((Node *) tle->expr),
+                                       exprTypmod((Node *) tle->expr),
+                                       0);
+                           if (exprType((Node *) outer_expr) !=
+                               exprType((Node *) sub_expr))
+                               outer_expr = (Expr *)
+                                   makeRelabelType(outer_expr,
+                                                   exprType((Node *) sub_expr),
+                                                   -1,
+                                                   COERCE_DONTCARE);
+                       }
+                       else
+                           continue;
+                   }
+
+                   /* Found a representation for this sub_pathkey */
+                   outer_ec = get_eclass_for_sort_expr(root,
+                                                       outer_expr,
+                                                       sub_member->em_datatype,
+                                                       sub_eclass->ec_opfamilies,
+                                                       0);
+                   outer_pk = make_canonical_pathkey(root,
+                                                     outer_ec,
+                                                     sub_pathkey->pk_opfamily,
+                                                     sub_pathkey->pk_strategy,
+                                                     sub_pathkey->pk_nulls_first);
+                   /* score = # of equivalence peers */
+                   score = list_length(outer_ec->ec_members) - 1;
+                   /* +1 if it matches the proper query_pathkeys item */
+                   if (retvallen < outer_query_keys &&
+                       list_nth(root->query_pathkeys, retvallen) == outer_pk)
+                       score++;
+                   if (score > best_score)
+                   {
+                       best_pathkey = outer_pk;
+                       best_score = score;
+                   }
                }
            }
        }
@@ -795,6 +861,7 @@ make_pathkeys_for_sortclauses(PlannerInfo *root,
                                             sortkey,
                                             sortcl->sortop,
                                             sortcl->nulls_first,
+                                            sortcl->tleSortGroupRef,
                                             canonicalize);
 
        /* Canonical form eliminates redundant ordering keys */
@@ -843,12 +910,14 @@ cache_mergeclause_eclasses(PlannerInfo *root, RestrictInfo *restrictinfo)
            get_eclass_for_sort_expr(root,
                                     (Expr *) get_leftop(clause),
                                     lefttype,
-                                    restrictinfo->mergeopfamilies);
+                                    restrictinfo->mergeopfamilies,
+                                    0);
        restrictinfo->right_ec =
            get_eclass_for_sort_expr(root,
                                     (Expr *) get_rightop(clause),
                                     righttype,
-                                    restrictinfo->mergeopfamilies);
+                                    restrictinfo->mergeopfamilies,
+                                    0);
    }
    else
        Assert(restrictinfo->right_ec != NULL);
index becb8255e87b22225a8a40ed2f7506900bfd8cb5..e2b46f970ce33e11e7149b3661dabc7f5650923d 100644 (file)
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.233 2007/11/08 19:25:37 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.234 2007/11/08 21:49:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2730,103 +2730,124 @@ make_sort_from_pathkeys(PlannerInfo *root, Plan *lefttree, List *pathkeys,
    foreach(i, pathkeys)
    {
        PathKey    *pathkey = (PathKey *) lfirst(i);
+       EquivalenceClass *ec = pathkey->pk_eclass;
        TargetEntry *tle = NULL;
        Oid         pk_datatype = InvalidOid;
        Oid         sortop;
        ListCell   *j;
 
-       /*
-        * We can sort by any non-constant expression listed in the pathkey's
-        * EquivalenceClass.  For now, we take the first one that corresponds
-        * to an available item in the tlist. If there isn't any, use the first
-        * one that is an expression in the input's vars.  (The non-const
-        * restriction only matters if the EC is below_outer_join; but if it
-        * isn't, it won't contain consts anyway, else we'd have discarded
-        * the pathkey as redundant.)
-        *
-        * XXX if we have a choice, is there any way of figuring out which
-        * might be cheapest to execute?  (For example, int4lt is likely much
-        * cheaper to execute than numericlt, but both might appear in the
-        * same equivalence class...)  Not clear that we ever will have an
-        * interesting choice in practice, so it may not matter.
-        */
-       foreach(j, pathkey->pk_eclass->ec_members)
+       if (ec->ec_has_volatile)
        {
-           EquivalenceMember *em = (EquivalenceMember *) lfirst(j);
-
-           if (em->em_is_const || em->em_is_child)
-               continue;
-
-           tle = tlist_member((Node *) em->em_expr, tlist);
-           if (tle)
-           {
-               pk_datatype = em->em_datatype;
-               break;          /* found expr already in tlist */
-           }
-
            /*
-            * We can also use it if the pathkey expression is a relabel
-            * of the tlist entry, or vice versa.  This is needed for
-            * binary-compatible cases (cf. make_pathkey_from_sortinfo).
-            * We prefer an exact match, though, so we do the basic
-            * search first.
+            * If the pathkey's EquivalenceClass is volatile, then it must
+            * have come from an ORDER BY clause, and we have to match it to
+            * that same targetlist entry.
             */
-           tle = tlist_member_ignore_relabel((Node *) em->em_expr, tlist);
-           if (tle)
-           {
-               pk_datatype = em->em_datatype;
-               break;          /* found expr already in tlist */
-           }
+           if (ec->ec_sortref == 0)        /* can't happen */
+               elog(ERROR, "volatile EquivalenceClass has no sortref");
+           tle = get_sortgroupref_tle(ec->ec_sortref, tlist);
+           Assert(tle);
+           Assert(list_length(ec->ec_members) == 1);
+           pk_datatype = ((EquivalenceMember *) linitial(ec->ec_members))->em_datatype;
        }
-       if (!tle)
+       else
        {
-           /* No matching tlist item; look for a computable expression */
-           Expr   *sortexpr = NULL;
-
-           foreach(j, pathkey->pk_eclass->ec_members)
+           /*
+            * Otherwise, we can sort by any non-constant expression listed in
+            * the pathkey's EquivalenceClass.  For now, we take the first one
+            * that corresponds to an available item in the tlist.  If there
+            * isn't any, use the first one that is an expression in the
+            * input's vars.  (The non-const restriction only matters if the
+            * EC is below_outer_join; but if it isn't, it won't contain
+            * consts anyway, else we'd have discarded the pathkey as
+            * redundant.)
+            *
+            * XXX if we have a choice, is there any way of figuring out which
+            * might be cheapest to execute?  (For example, int4lt is likely
+            * much cheaper to execute than numericlt, but both might appear
+            * in the same equivalence class...)  Not clear that we ever will
+            * have an interesting choice in practice, so it may not matter.
+            */
+           foreach(j, ec->ec_members)
            {
                EquivalenceMember *em = (EquivalenceMember *) lfirst(j);
-               List       *exprvars;
-               ListCell   *k;
 
                if (em->em_is_const || em->em_is_child)
                    continue;
-               sortexpr = em->em_expr;
-               exprvars = pull_var_clause((Node *) sortexpr, false);
-               foreach(k, exprvars)
+
+               tle = tlist_member((Node *) em->em_expr, tlist);
+               if (tle)
                {
-                   if (!tlist_member_ignore_relabel(lfirst(k), tlist))
-                       break;
+                   pk_datatype = em->em_datatype;
+                   break;          /* found expr already in tlist */
                }
-               list_free(exprvars);
-               if (!k)
+
+               /*
+                * We can also use it if the pathkey expression is a relabel
+                * of the tlist entry, or vice versa.  This is needed for
+                * binary-compatible cases (cf. make_pathkey_from_sortinfo).
+                * We prefer an exact match, though, so we do the basic
+                * search first.
+                */
+               tle = tlist_member_ignore_relabel((Node *) em->em_expr, tlist);
+               if (tle)
                {
                    pk_datatype = em->em_datatype;
-                   break;      /* found usable expression */
+                   break;          /* found expr already in tlist */
                }
            }
-           if (!j)
-               elog(ERROR, "could not find pathkey item to sort");
 
-           /*
-            * Do we need to insert a Result node?
-            */
-           if (!is_projection_capable_plan(lefttree))
+           if (!tle)
            {
-               /* copy needed so we don't modify input's tlist below */
-               tlist = copyObject(tlist);
-               lefttree = (Plan *) make_result(root, tlist, NULL, lefttree);
-           }
+               /* No matching tlist item; look for a computable expression */
+               Expr   *sortexpr = NULL;
 
-           /*
-            * Add resjunk entry to input's tlist
-            */
-           tle = makeTargetEntry(sortexpr,
-                                 list_length(tlist) + 1,
-                                 NULL,
-                                 true);
-           tlist = lappend(tlist, tle);
-           lefttree->targetlist = tlist;       /* just in case NIL before */
+               foreach(j, ec->ec_members)
+               {
+                   EquivalenceMember *em = (EquivalenceMember *) lfirst(j);
+                   List       *exprvars;
+                   ListCell   *k;
+
+                   if (em->em_is_const || em->em_is_child)
+                       continue;
+                   sortexpr = em->em_expr;
+                   exprvars = pull_var_clause((Node *) sortexpr, false);
+                   foreach(k, exprvars)
+                   {
+                       if (!tlist_member_ignore_relabel(lfirst(k), tlist))
+                           break;
+                   }
+                   list_free(exprvars);
+                   if (!k)
+                   {
+                       pk_datatype = em->em_datatype;
+                       break;      /* found usable expression */
+                   }
+               }
+               if (!j)
+                   elog(ERROR, "could not find pathkey item to sort");
+
+               /*
+                * Do we need to insert a Result node?
+                */
+               if (!is_projection_capable_plan(lefttree))
+               {
+                   /* copy needed so we don't modify input's tlist below */
+                   tlist = copyObject(tlist);
+                   lefttree = (Plan *) make_result(root, tlist, NULL,
+                                                   lefttree);
+               }
+
+               /*
+                * Add resjunk entry to input's tlist
+                */
+               tle = makeTargetEntry(sortexpr,
+                                     list_length(tlist) + 1,
+                                     NULL,
+                                     true);
+               tlist = lappend(tlist, tle);
+               lefttree->targetlist = tlist;   /* just in case NIL before */
+           }
        }
 
        /*
index e58fe7dc7f1af828bc6ff1e469b699b2fc52edc6..d2ac14cfa1bcf93f6556997b15ae7285de9cf27a 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *   $PostgreSQL: pgsql/src/backend/optimizer/util/tlist.c,v 1.75 2007/11/08 19:25:37 tgl Exp $
+ *   $PostgreSQL: pgsql/src/backend/optimizer/util/tlist.c,v 1.76 2007/11/08 21:49:47 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -131,26 +131,22 @@ add_to_flat_tlist(List *tlist, List *vars)
    return tlist;
 }
 
+
 /*
- * get_sortgroupclause_tle
- *     Find the targetlist entry matching the given SortClause
- *     (or GroupClause) by ressortgroupref, and return it.
- *
- * Because GroupClause is typedef'd as SortClause, either kind of
- * node can be passed without casting.
+ * get_sortgroupref_tle
+ *     Find the targetlist entry matching the given SortGroupRef index,
+ *     and return it.
  */
 TargetEntry *
-get_sortgroupclause_tle(SortClause *sortClause,
-                       List *targetList)
+get_sortgroupref_tle(Index sortref, List *targetList)
 {
-   Index       refnumber = sortClause->tleSortGroupRef;
    ListCell   *l;
 
    foreach(l, targetList)
    {
        TargetEntry *tle = (TargetEntry *) lfirst(l);
 
-       if (tle->ressortgroupref == refnumber)
+       if (tle->ressortgroupref == sortref)
            return tle;
    }
 
@@ -158,6 +154,21 @@ get_sortgroupclause_tle(SortClause *sortClause,
    return NULL;                /* keep compiler quiet */
 }
 
+/*
+ * get_sortgroupclause_tle
+ *     Find the targetlist entry matching the given SortClause
+ *     (or GroupClause) by ressortgroupref, and return it.
+ *
+ * Because GroupClause is typedef'd as SortClause, either kind of
+ * node can be passed without casting.
+ */
+TargetEntry *
+get_sortgroupclause_tle(SortClause *sortClause,
+                       List *targetList)
+{
+   return get_sortgroupref_tle(sortClause->tleSortGroupRef, targetList);
+}
+
 /*
  * get_sortgroupclause_expr
  *     Find the targetlist entry matching the given SortClause
index 389035202223be64409f62cc5384ab40f661ebe5..db6eef209644c2c477d8ae4417ae97b9df38214c 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.147 2007/10/11 18:05:27 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.148 2007/11/08 21:49:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -449,7 +449,10 @@ typedef struct IndexOptInfo
  * which is a case that can't arise otherwise since clauses containing
  * volatile functions are never considered mergejoinable.  We mark such
  * EquivalenceClasses specially to prevent them from being merged with
- * ordinary EquivalenceClasses.
+ * ordinary EquivalenceClasses.  Also, for volatile expressions we have
+ * to be careful to match the EquivalenceClass to the correct targetlist
+ * entry: consider SELECT random() AS a, random() AS b ... ORDER BY b,a.
+ * So we record the SortGroupRef of the originating sort clause.
  *
  * We allow equality clauses appearing below the nullable side of an outer join
  * to form EquivalenceClasses, but these have a slightly different meaning:
@@ -472,6 +475,7 @@ typedef struct EquivalenceClass
    bool        ec_has_volatile;    /* the (sole) member is a volatile expr */
    bool        ec_below_outer_join;    /* equivalence applies below an OJ */
    bool        ec_broken;          /* failed to generate needed clauses? */
+   Index       ec_sortref;         /* originating sortclause label, or 0 */
    struct EquivalenceClass *ec_merged;     /* set if merged into another EC */
 } EquivalenceClass;
 
index cbde0c7b9a5a97915eb17596d6ef40c991a8d33c..cf589b48af7265d577cb84d2a6daeafc0a810974 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.99 2007/09/26 18:51:51 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.100 2007/11/08 21:49:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -115,7 +115,8 @@ extern void reconsider_outer_join_clauses(PlannerInfo *root);
 extern EquivalenceClass *get_eclass_for_sort_expr(PlannerInfo *root,
                         Expr *expr,
                         Oid expr_datatype,
-                        List *opfamilies);
+                        List *opfamilies,
+                        Index sortref);
 extern void generate_base_implied_equalities(PlannerInfo *root);
 extern List *generate_join_implied_equalities(PlannerInfo *root,
                                              RelOptInfo *joinrel,
index bb127cbce2b62bedd9ed769a284be6af62091267..515339363abecb77fc312e946ec3710bd49375bf 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2007, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/tlist.h,v 1.46 2007/11/08 19:25:37 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/tlist.h,v 1.47 2007/11/08 21:49:48 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -23,6 +23,8 @@ extern TargetEntry *tlist_member_ignore_relabel(Node *node, List *targetlist);
 extern List *flatten_tlist(List *tlist);
 extern List *add_to_flat_tlist(List *tlist, List *vars);
 
+extern TargetEntry *get_sortgroupref_tle(Index sortref,
+                       List *targetList);
 extern TargetEntry *get_sortgroupclause_tle(SortClause *sortClause,
                        List *targetList);
 extern Node *get_sortgroupclause_expr(SortClause *sortClause,