Fix a bunch of bad interactions between partial indexes and the new
authorTom Lane <tgl@sss.pgh.pa.us>
Thu, 28 Jul 2005 20:26:22 +0000 (20:26 +0000)
committerTom Lane <tgl@sss.pgh.pa.us>
Thu, 28 Jul 2005 20:26:22 +0000 (20:26 +0000)
planning logic for bitmap indexscans.  Partial indexes create corner
cases in which a scan might be done with no explicit index qual conditions,
and the code wasn't handling those cases nicely.  Also be a little
tenser about eliminating redundant clauses in the generated plan.
Per report from Dmitry Karasik.

src/backend/nodes/list.c
src/backend/optimizer/path/indxpath.c
src/backend/optimizer/path/orindxpath.c
src/backend/optimizer/plan/createplan.c
src/backend/optimizer/plan/planagg.c
src/backend/optimizer/util/restrictinfo.c
src/include/nodes/pg_list.h
src/include/optimizer/paths.h
src/include/optimizer/restrictinfo.h

index b56cfe3791c0840aa64dcf71c043fc72c234c327..80043834b63c05eaa8efe227d6b4cd48445f65f9 100644 (file)
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/nodes/list.c,v 1.64 2005/03/17 05:47:01 neilc Exp $
+ *       $PostgreSQL: pgsql/src/backend/nodes/list.c,v 1.65 2005/07/28 20:26:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -686,9 +686,13 @@ list_delete_first(List *list)
  * The returned list is newly-allocated, although the content of the
  * cells is the same (i.e. any pointed-to objects are not copied).
  *
- * NB: Bizarrely, this function will NOT remove any duplicates that
- * are present in list1 (so it is not really a union at all!). Also,
- * this function could probably be implemented a lot faster if it is a
+ * NB: this function will NOT remove any duplicates that are present
+ * in list1 (so it only performs a "union" if list1 is known unique to
+ * start with).  Also, if you are about to write "x = list_union(x, y)"
+ * you probably want to use list_concat_unique() instead to avoid wasting
+ * the list cells of the old x list.
+ *
+ * This function could probably be implemented a lot faster if it is a
  * performance bottleneck.
  */
 List *
@@ -888,7 +892,153 @@ list_difference_oid(List *list1, List *list2)
        return result;
 }
 
-/* Free all storage in a list, and optionally the pointed-to elements */
+/*
+ * Append datum to list, but only if it isn't already in the list.
+ *
+ * Whether an element is already a member of the list is determined
+ * via equal().
+ */
+List *
+list_append_unique(List *list, void *datum)
+{
+       if (list_member(list, datum))
+               return list;
+       else
+               return lappend(list, datum);
+}
+
+/*
+ * This variant of list_append_unique() determines list membership via
+ * simple pointer equality.
+ */
+List *
+list_append_unique_ptr(List *list, void *datum)
+{
+       if (list_member_ptr(list, datum))
+               return list;
+       else
+               return lappend(list, datum);
+}
+
+/*
+ * This variant of list_append_unique() operates upon lists of integers.
+ */
+List *
+list_append_unique_int(List *list, int datum)
+{
+       if (list_member_int(list, datum))
+               return list;
+       else
+               return lappend_int(list, datum);
+}
+
+/*
+ * This variant of list_append_unique() operates upon lists of OIDs.
+ */
+List *
+list_append_unique_oid(List *list, Oid datum)
+{
+       if (list_member_oid(list, datum))
+               return list;
+       else
+               return lappend_oid(list, datum);
+}
+
+/*
+ * Append to list1 each member of list2 that isn't already in list1.
+ *
+ * Whether an element is already a member of the list is determined
+ * via equal().
+ *
+ * This is almost the same functionality as list_union(), but list1 is
+ * modified in-place rather than being copied.  Note also that list2's cells
+ * are not inserted in list1, so the analogy to list_concat() isn't perfect.
+ */
+List *
+list_concat_unique(List *list1, List *list2)
+{
+       ListCell   *cell;
+
+       Assert(IsPointerList(list1));
+       Assert(IsPointerList(list2));
+
+       foreach(cell, list2)
+       {
+               if (!list_member(list1, lfirst(cell)))
+                       list1 = lappend(list1, lfirst(cell));
+       }
+
+       check_list_invariants(list1);
+       return list1;
+}
+
+/*
+ * This variant of list_concat_unique() determines list membership via
+ * simple pointer equality.
+ */
+List *
+list_concat_unique_ptr(List *list1, List *list2)
+{
+       ListCell   *cell;
+
+       Assert(IsPointerList(list1));
+       Assert(IsPointerList(list2));
+
+       foreach(cell, list2)
+       {
+               if (!list_member_ptr(list1, lfirst(cell)))
+                       list1 = lappend(list1, lfirst(cell));
+       }
+
+       check_list_invariants(list1);
+       return list1;
+}
+
+/*
+ * This variant of list_concat_unique() operates upon lists of integers.
+ */
+List *
+list_concat_unique_int(List *list1, List *list2)
+{
+       ListCell   *cell;
+
+       Assert(IsIntegerList(list1));
+       Assert(IsIntegerList(list2));
+
+       foreach(cell, list2)
+       {
+               if (!list_member_int(list1, lfirst_int(cell)))
+                       list1 = lappend_int(list1, lfirst_int(cell));
+       }
+
+       check_list_invariants(list1);
+       return list1;
+}
+
+/*
+ * This variant of list_concat_unique() operates upon lists of OIDs.
+ */
+List *
+list_concat_unique_oid(List *list1, List *list2)
+{
+       ListCell   *cell;
+
+       Assert(IsOidList(list1));
+       Assert(IsOidList(list2));
+
+       foreach(cell, list2)
+       {
+               if (!list_member_oid(list1, lfirst_oid(cell)))
+                       list1 = lappend_oid(list1, lfirst_oid(cell));
+       }
+
+       check_list_invariants(list1);
+       return list1;
+}
+
+/*
+ * Free all storage in a list, and optionally the pointed-to elements
+ */
 static void
 list_free_private(List *list, bool deep)
 {
index 07b67a88228174e30d632ed841a48bb028a5461d..bd0b09fcfe9f9baf14a4191e7eadce6a2a806669 100644 (file)
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.186 2005/07/02 23:00:40 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.187 2005/07/28 20:26:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -212,6 +212,8 @@ create_index_paths(PlannerInfo *root, RelOptInfo *rel)
  * subclause to any index on x alone, because such a Path would already have
  * been generated at the upper level.  So we could use an index on x,y,z
  * or an index on x,y for the OR subclause, but not an index on just x.
+ * When dealing with a partial index, a match of the index predicate to
+ * one of the "current" clauses also makes the index usable.
  *
  * If istoplevel is true (indicating we are considering the top level of a
  * rel's restriction clauses), we will include indexes in the result that
@@ -248,6 +250,8 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
                List       *restrictclauses;
                List       *index_pathkeys;
                List       *useful_pathkeys;
+               bool            useful_predicate;
+               bool            found_clause;
                bool            index_is_ordered;
 
                /*
@@ -258,29 +262,60 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
                 * Otherwise, we have to test whether the added clauses are
                 * sufficient to imply the predicate.  If so, we could use
                 * the index in the current context.
+                *
+                * We set useful_predicate to true iff the predicate was proven
+                * using the current set of clauses.  This is needed to prevent
+                * matching a predOK index to an arm of an OR, which would be
+                * a legal but pointlessly inefficient plan.  (A better plan will
+                * be generated by just scanning the predOK index alone, no OR.)
                 */
-               if (index->indpred != NIL && !index->predOK)
+               useful_predicate = false;
+               if (index->indpred != NIL)
                {
-                       if (istoplevel)
-                               continue;               /* no point in trying to prove it */
+                       if (index->predOK)
+                       {
+                               if (istoplevel)
+                               {
+                                       /* we know predicate was proven from these clauses */
+                                       useful_predicate = true;
+                               }
+                       }
+                       else
+                       {
+                               if (istoplevel)
+                                       continue;               /* no point in trying to prove it */
 
-                       /* Form all_clauses if not done already */
-                       if (all_clauses == NIL)
-                               all_clauses = list_concat(list_copy(clauses),
-                                                                                 outer_clauses);
+                               /* Form all_clauses if not done already */
+                               if (all_clauses == NIL)
+                                       all_clauses = list_concat(list_copy(clauses),
+                                                                                         outer_clauses);
 
-                       if (!predicate_implied_by(index->indpred, all_clauses) ||
-                               predicate_implied_by(index->indpred, outer_clauses))
-                               continue;
+                               if (!predicate_implied_by(index->indpred, all_clauses))
+                                       continue;               /* can't use it at all */
+
+                               if (!predicate_implied_by(index->indpred, outer_clauses))
+                                       useful_predicate = true;
+                       }
                }
 
                /*
                 * 1. Match the index against the available restriction clauses.
+                * found_clause is set true only if at least one of the current
+                * clauses was used.
                 */
                restrictclauses = group_clauses_by_indexkey(index,
                                                                                                        clauses,
                                                                                                        outer_clauses,
-                                                                                                       outer_relids);
+                                                                                                       outer_relids,
+                                                                                                       &found_clause);
+
+               /*
+                * Not all index AMs support scans with no restriction clauses.
+                * We can't generate a scan over an index with amoptionalkey = false
+                * unless there's at least one restriction clause.
+                */
+               if (restrictclauses == NIL && !index->amoptionalkey)
+                       continue;
 
                /*
                 * 2. Compute pathkeys describing index's ordering, if any, then
@@ -300,20 +335,12 @@ find_usable_indexes(PlannerInfo *root, RelOptInfo *rel,
 
                /*
                 * 3. Generate an indexscan path if there are relevant restriction
-                * clauses OR the index ordering is potentially useful for later
-                * merging or final output ordering.
-                *
-                * If there is a predicate, consider it anyway since the index
-                * predicate has already been found to match the query.  The
-                * selectivity of the predicate might alone make the index useful.
-                *
-                * Note: not all index AMs support scans with no restriction clauses.
-                * We can't generate a scan over an index with amoptionalkey = false
-                * unless there's at least one restriction clause.
+                * clauses in the current clauses, OR the index ordering is
+                * potentially useful for later merging or final output ordering,
+                * OR the index has a predicate that was proven by the current
+                * clauses.
                 */
-               if (restrictclauses != NIL ||
-                       (index->amoptionalkey &&
-                        (useful_pathkeys != NIL || index->indpred != NIL)))
+               if (found_clause || useful_pathkeys != NIL || useful_predicate)
                {
                        ipath = create_index_path(root, index,
                                                                          restrictclauses,
@@ -627,10 +654,9 @@ bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
  * with one index key (in no particular order); the top list is ordered by
  * index key.  (This is depended on by expand_indexqual_conditions().)
  *
- * As explained in the comments for find_usable_indexes(), we can use
- * clauses from either of the given lists, but the result is required to
- * use at least one clause from the "current clauses" list.  We return
- * NIL if we don't find any such clause.
+ * We can use clauses from either the current clauses or outer_clauses lists,
+ * but *found_clause is set TRUE only if we used at least one clause from
+ * the "current clauses" list.  See find_usable_indexes() for motivation.
  *
  * outer_relids determines what Vars will be allowed on the other side
  * of a possible index qual; see match_clause_to_indexcol().
@@ -643,18 +669,25 @@ bitmap_and_cost_est(PlannerInfo *root, RelOptInfo *rel, List *paths)
  * Example: given an index on (A,B,C), we would return ((C1 C2) () (C3 C4))
  * if we find that clauses C1 and C2 use column A, clauses C3 and C4 use
  * column C, and no clauses use column B.
+ *
+ * Note: in some circumstances we may find the same RestrictInfos coming
+ * from multiple places.  Defend against redundant outputs by using
+ * list_append_unique_ptr (pointer equality should be good enough).
  */
 List *
 group_clauses_by_indexkey(IndexOptInfo *index,
                                                  List *clauses, List *outer_clauses,
-                                                 Relids outer_relids)
+                                                 Relids outer_relids,
+                                                 bool *found_clause)
 {
        List       *clausegroup_list = NIL;
-       bool            found_clause = false;
+       bool            found_outer_clause = false;
        int                     indexcol = 0;
        Oid                *classes = index->classlist;
 
-       if (clauses == NIL)
+       *found_clause = false;          /* default result */
+
+       if (clauses == NIL && outer_clauses == NIL)
                return NIL;                             /* cannot succeed */
 
        do
@@ -675,8 +708,8 @@ group_clauses_by_indexkey(IndexOptInfo *index,
                                                                                 rinfo,
                                                                                 outer_relids))
                        {
-                               clausegroup = lappend(clausegroup, rinfo);
-                               found_clause = true;
+                               clausegroup = list_append_unique_ptr(clausegroup, rinfo);
+                               *found_clause = true;
                        }
                }
 
@@ -691,7 +724,10 @@ group_clauses_by_indexkey(IndexOptInfo *index,
                                                                                 curClass,
                                                                                 rinfo,
                                                                                 outer_relids))
-                               clausegroup = lappend(clausegroup, rinfo);
+                       {
+                               clausegroup = list_append_unique_ptr(clausegroup, rinfo);
+                               found_outer_clause = true;
+                       }
                }
 
                /*
@@ -707,8 +743,8 @@ group_clauses_by_indexkey(IndexOptInfo *index,
 
        } while (!DoneMatchingIndexKeys(classes));
 
-       if (!found_clause)
-               return NIL;
+       if (!*found_clause && !found_outer_clause)
+               return NIL;                             /* no indexable clauses anywhere */
 
        return clausegroup_list;
 }
index 884329edd9723f5b130576fb1db3119f5279cddb..eb1e1a6ffcd46453f4fbfb8c3fc3bb6fdcdf99a1 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/path/orindxpath.c,v 1.73 2005/07/02 23:00:40 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/path/orindxpath.c,v 1.74 2005/07/28 20:26:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -134,14 +134,24 @@ create_or_index_quals(PlannerInfo *root, RelOptInfo *rel)
                return false;
 
        /*
-        * Convert the path's indexclauses structure to a RestrictInfo tree,
-        * and add it to the rel's restriction list.
+        * Convert the path's indexclauses structure to a RestrictInfo tree.
+        * We include any partial-index predicates so as to get a reasonable
+        * representation of what the path is actually scanning.
         */
-       newrinfos = make_restrictinfo_from_bitmapqual((Path *) bestpath, true);
-       Assert(list_length(newrinfos) == 1);
+       newrinfos = make_restrictinfo_from_bitmapqual((Path *) bestpath,
+                                                                                                 true, true);
+
+       /* It's possible we get back something other than a single OR clause */
+       if (list_length(newrinfos) != 1)
+               return false;
        or_rinfo = (RestrictInfo *) linitial(newrinfos);
        Assert(IsA(or_rinfo, RestrictInfo));
+       if (!restriction_is_or_clause(or_rinfo))
+               return false;
 
+       /*
+        * OK, add it to the rel's restriction list.
+        */
        rel->baserestrictinfo = list_concat(rel->baserestrictinfo, newrinfos);
 
        /*
index 6c4c345ca8eabfba85241d908b65d5c006bce19d..697355cfdf87b056f9f8eca9d9a2ca87a24f96ff 100644 (file)
@@ -10,7 +10,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.195 2005/07/23 21:05:46 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/plan/createplan.c,v 1.196 2005/07/28 20:26:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -900,7 +900,7 @@ create_bitmap_scan_plan(PlannerInfo *root,
         */
        if (best_path->isjoininner)
        {
-               scan_clauses = list_union(scan_clauses, bitmapqualorig);
+               scan_clauses = list_concat_unique(scan_clauses, bitmapqualorig);
        }
 
        /*
@@ -962,6 +962,9 @@ create_bitmap_scan_plan(PlannerInfo *root,
  * (in implicit-AND form, without RestrictInfos) describing the original index
  * conditions and the generated indexqual conditions.  The latter is made to
  * exclude lossy index operators.
+ *
+ * Note: if you find yourself changing this, you probably need to change
+ * make_restrictinfo_from_bitmapqual too.
  */
 static Plan *
 create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
@@ -977,6 +980,13 @@ create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
                List       *subindexquals = NIL;
                ListCell   *l;
 
+               /*
+                * There may well be redundant quals among the subplans, since a
+                * top-level WHERE qual might have gotten used to form several
+                * different index quals.  We don't try exceedingly hard to
+                * eliminate redundancies, but we do eliminate obvious duplicates
+                * by using list_concat_unique.
+                */
                foreach(l, apath->bitmapquals)
                {
                        Plan   *subplan;
@@ -986,8 +996,8 @@ create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
                        subplan = create_bitmap_subplan(root, (Path *) lfirst(l),
                                                                                        &subqual, &subindexqual);
                        subplans = lappend(subplans, subplan);
-                       subquals = list_concat(subquals, subqual);
-                       subindexquals = list_concat(subindexquals, subindexqual);
+                       subquals = list_concat_unique(subquals, subqual);
+                       subindexquals = list_concat_unique(subindexquals, subindexqual);
                }
                plan = (Plan *) make_bitmap_and(subplans);
                plan->startup_cost = apath->path.startup_cost;
@@ -1004,8 +1014,15 @@ create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
                List       *subplans = NIL;
                List       *subquals = NIL;
                List       *subindexquals = NIL;
+               bool            const_true_subqual = false;
+               bool            const_true_subindexqual = false;
                ListCell   *l;
 
+               /*
+                * Here, we detect both obvious redundancies and qual-free subplans.
+                * A qual-free subplan would cause us to generate "... OR true ..."
+                * which we may as well reduce to just "true".
+                */
                foreach(l, opath->bitmapquals)
                {
                        Plan   *subplan;
@@ -1015,10 +1032,16 @@ create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
                        subplan = create_bitmap_subplan(root, (Path *) lfirst(l),
                                                                                        &subqual, &subindexqual);
                        subplans = lappend(subplans, subplan);
-                       subquals = lappend(subquals,
-                                                          make_ands_explicit(subqual));
-                       subindexquals = lappend(subindexquals,
-                                                                       make_ands_explicit(subindexqual));
+                       if (subqual == NIL)
+                               const_true_subqual = true;
+                       else if (!const_true_subqual)
+                               subquals = list_append_unique(subquals,
+                                                                                         make_ands_explicit(subqual));
+                       if (subindexqual == NIL)
+                               const_true_subindexqual = true;
+                       else if (!const_true_subindexqual)
+                               subindexquals = list_append_unique(subindexquals,
+                                                                                                  make_ands_explicit(subindexqual));
                }
                plan = (Plan *) make_bitmap_or(subplans);
                plan->startup_cost = opath->path.startup_cost;
@@ -1026,8 +1049,23 @@ create_bitmap_subplan(PlannerInfo *root, Path *bitmapqual,
                plan->plan_rows =
                        clamp_row_est(opath->bitmapselectivity * opath->path.parent->tuples);
                plan->plan_width = 0;   /* meaningless */
-               *qual = list_make1(make_orclause(subquals));
-               *indexqual = list_make1(make_orclause(subindexquals));
+               /*
+                * If there were constant-TRUE subquals, the OR reduces to constant
+                * TRUE.  Also, avoid generating one-element ORs, which could happen
+                * due to redundancy elimination.
+                */
+               if (const_true_subqual)
+                       *qual = NIL;
+               else if (list_length(subquals) <= 1)
+                       *qual = subquals;
+               else
+                       *qual = list_make1(make_orclause(subquals));
+               if (const_true_subindexqual)
+                       *indexqual = NIL;
+               else if (list_length(subindexquals) <= 1)
+                       *indexqual = subindexquals;
+               else
+                       *indexqual = list_make1(make_orclause(subindexquals));
        }
        else if (IsA(bitmapqual, IndexPath))
        {
@@ -1204,6 +1242,14 @@ create_nestloop_plan(PlannerInfo *root,
        {
                /*
                 * Same deal for bitmapped index scans.
+                *
+                * Note: both here and above, we ignore any implicit index restrictions
+                * associated with the use of partial indexes.  This is OK because
+                * we're only trying to prove we can dispense with some join quals;
+                * failing to prove that doesn't result in an incorrect plan.  It is
+                * the right way to proceed because adding more quals to the stuff
+                * we got from the original query would just make it harder to detect
+                * duplication.
                 */
                BitmapHeapPath *innerpath = (BitmapHeapPath *) best_path->innerjoinpath;
 
@@ -1212,7 +1258,9 @@ create_nestloop_plan(PlannerInfo *root,
                        List       *bitmapclauses;
 
                        bitmapclauses =
-                               make_restrictinfo_from_bitmapqual(innerpath->bitmapqual, true);
+                               make_restrictinfo_from_bitmapqual(innerpath->bitmapqual,
+                                                                                                 true,
+                                                                                                 false);
                        joinrestrictclauses =
                                select_nonredundant_join_clauses(root,
                                                                                                 joinrestrictclauses,
index 0208e910536929432c34d140cbd3e3e12e823b39..81f526ac11398df91876c6ed0f3986e96691c609 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.6 2005/07/23 21:05:46 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/plan/planagg.c,v 1.7 2005/07/28 20:26:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -313,6 +313,7 @@ build_minmax_path(PlannerInfo *root, RelOptInfo *rel, MinMaxAggInfo *info)
                List       *restrictclauses;
                IndexPath  *new_path;
                Cost            new_cost;
+               bool            found_clause;
 
                /* Ignore non-btree indexes */
                if (index->relam != BTREE_AM_OID)
@@ -346,7 +347,8 @@ build_minmax_path(PlannerInfo *root, RelOptInfo *rel, MinMaxAggInfo *info)
                restrictclauses = group_clauses_by_indexkey(index,
                                                                                                        index->rel->baserestrictinfo,
                                                                                                        NIL,
-                                                                                                       NULL);
+                                                                                                       NULL,
+                                                                                                       &found_clause);
 
                if (list_length(restrictclauses) < indexcol)
                        continue;                       /* definitely haven't got enough */
index ba3d82dd30756c176622c1d0439170409ceb98e0..deb16152fb8bbca952eb31d43f2d31d767ac5b50 100644 (file)
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.38 2005/07/02 23:00:41 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/optimizer/util/restrictinfo.c,v 1.39 2005/07/28 20:26:21 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -17,6 +17,7 @@
 #include "optimizer/clauses.h"
 #include "optimizer/cost.h"
 #include "optimizer/paths.h"
+#include "optimizer/predtest.h"
 #include "optimizer/restrictinfo.h"
 #include "optimizer/var.h"
 
@@ -70,31 +71,49 @@ make_restrictinfo(Expr *clause, bool is_pushed_down, Relids required_relids)
  * RestrictInfo node(s) equivalent to the condition represented by the
  * indexclauses of the Path structure.
  *
- * The result is a List since we might need to return multiple RestrictInfos.
+ * The result is a List (effectively, implicit-AND representation) of
+ * RestrictInfos.
+ *
+ * If include_predicates is true, we add any partial index predicates to
+ * the explicit index quals.  When this is not true, we return a condition
+ * that might be weaker than the actual scan represents.
  *
  * To do this through the normal make_restrictinfo() API, callers would have
  * to strip off the RestrictInfo nodes present in the indexclauses lists, and
  * then make_restrictinfo() would have to build new ones.  It's better to have
  * a specialized routine to allow sharing of RestrictInfos.
+ *
+ * The qual manipulations here are much the same as in create_bitmap_subplan;
+ * keep the two routines in sync!
  */
 List *
-make_restrictinfo_from_bitmapqual(Path *bitmapqual, bool is_pushed_down)
+make_restrictinfo_from_bitmapqual(Path *bitmapqual,
+                                                                 bool is_pushed_down,
+                                                                 bool include_predicates)
 {
        List       *result;
+       ListCell   *l;
 
        if (IsA(bitmapqual, BitmapAndPath))
        {
                BitmapAndPath *apath = (BitmapAndPath *) bitmapqual;
-               ListCell   *l;
 
+               /*
+                * There may well be redundant quals among the subplans, since a
+                * top-level WHERE qual might have gotten used to form several
+                * different index quals.  We don't try exceedingly hard to
+                * eliminate redundancies, but we do eliminate obvious duplicates
+                * by using list_concat_unique.
+                */
                result = NIL;
                foreach(l, apath->bitmapquals)
                {
                        List       *sublist;
 
                        sublist = make_restrictinfo_from_bitmapqual((Path *) lfirst(l),
-                                                                                                               is_pushed_down);
-                       result = list_concat(result, sublist);
+                                                                                                               is_pushed_down,
+                                                                                                               include_predicates);
+                       result = list_concat_unique(result, sublist);
                }
        }
        else if (IsA(bitmapqual, BitmapOrPath))
@@ -102,38 +121,77 @@ make_restrictinfo_from_bitmapqual(Path *bitmapqual, bool is_pushed_down)
                BitmapOrPath *opath = (BitmapOrPath *) bitmapqual;
                List       *withris = NIL;
                List       *withoutris = NIL;
-               ListCell   *l;
 
+               /*
+                * Here, we detect both obvious redundancies and qual-free subplans.
+                * A qual-free subplan would cause us to generate "... OR true ..."
+                * which we may as well reduce to just "true".
+                */
                foreach(l, opath->bitmapquals)
                {
                        List       *sublist;
 
                        sublist = make_restrictinfo_from_bitmapqual((Path *) lfirst(l),
-                                                                                                               is_pushed_down);
+                                                                                                               is_pushed_down,
+                                                                                                               include_predicates);
                        if (sublist == NIL)
                        {
-                               /* constant TRUE input yields constant TRUE OR result */
-                               /* (though this probably cannot happen) */
+                               /*
+                                * If we find a qual-less subscan, it represents a constant
+                                * TRUE, and hence the OR result is also constant TRUE, so
+                                * we can stop here.
+                                */
                                return NIL;
                        }
                        /* Create AND subclause with RestrictInfos */
-                       withris = lappend(withris, make_ands_explicit(sublist));
+                       withris = list_append_unique(withris,
+                                                                                make_ands_explicit(sublist));
                        /* And one without */
                        sublist = get_actual_clauses(sublist);
-                       withoutris = lappend(withoutris, make_ands_explicit(sublist));
+                       withoutris = list_append_unique(withoutris,
+                                                                                       make_ands_explicit(sublist));
+               }
+
+               /*
+                * Avoid generating one-element ORs, which could happen
+                * due to redundancy elimination.
+                */
+               if (list_length(withris) <= 1)
+                       result = withris;
+               else
+               {
+                       /* Here's the magic part not available to outside callers */
+                       result =
+                               list_make1(make_restrictinfo_internal(make_orclause(withoutris),
+                                                                                                         make_orclause(withris),
+                                                                                                         is_pushed_down,
+                                                                                                         NULL));
                }
-               /* Here's the magic part not available to outside callers */
-               result =
-                       list_make1(make_restrictinfo_internal(make_orclause(withoutris),
-                                                                                                 make_orclause(withris),
-                                                                                                 is_pushed_down,
-                                                                                                 NULL));
        }
        else if (IsA(bitmapqual, IndexPath))
        {
                IndexPath *ipath = (IndexPath *) bitmapqual;
 
                result = list_copy(ipath->indexclauses);
+               if (include_predicates && ipath->indexinfo->indpred != NIL)
+               {
+                       foreach(l, ipath->indexinfo->indpred)
+                       {
+                               Expr   *pred = (Expr *) lfirst(l);
+
+                               /*
+                                * We know that the index predicate must have been implied
+                                * by the query condition as a whole, but it may or may not
+                                * be implied by the conditions that got pushed into the
+                                * bitmapqual.  Avoid generating redundant conditions.
+                                */
+                               if (!predicate_implied_by(list_make1(pred), result))
+                                       result = lappend(result,
+                                                                        make_restrictinfo(pred,
+                                                                                                          is_pushed_down,
+                                                                                                          NULL));
+                       }
+               }
        }
        else
        {
index d54337d8148cc2f307af11b7c31645f66e4006ce..564745e9a59c0b4a0af081d3a39ae06661ce2949 100644 (file)
@@ -30,7 +30,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/pg_list.h,v 1.51 2004/12/31 22:03:34 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/pg_list.h,v 1.52 2005/07/28 20:26:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -224,6 +224,16 @@ extern List *list_difference_ptr(List *list1, List *list2);
 extern List *list_difference_int(List *list1, List *list2);
 extern List *list_difference_oid(List *list1, List *list2);
 
+extern List *list_append_unique(List *list, void *datum);
+extern List *list_append_unique_ptr(List *list, void *datum);
+extern List *list_append_unique_int(List *list, int datum);
+extern List *list_append_unique_oid(List *list, Oid datum);
+
+extern List *list_concat_unique(List *list1, List *list2);
+extern List *list_concat_unique_ptr(List *list1, List *list2);
+extern List *list_concat_unique_int(List *list1, List *list2);
+extern List *list_concat_unique_oid(List *list1, List *list2);
+
 extern void list_free(List *list);
 extern void list_free_deep(List *list);
 
index be46bf53dd4f4de4739bdf98f5822dd60f763c28..8f26c8e8f0d96d2a206d6990dbbf9e39865400c5 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.85 2005/06/10 22:25:37 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/paths.h,v 1.86 2005/07/28 20:26:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,7 +43,8 @@ extern Path *best_inner_indexscan(PlannerInfo *root, RelOptInfo *rel,
                                         Relids outer_relids, JoinType jointype);
 extern List *group_clauses_by_indexkey(IndexOptInfo *index,
                                                                           List *clauses, List *outer_clauses,
-                                                                          Relids outer_relids);
+                                                                          Relids outer_relids,
+                                                                          bool *found_clause);
 extern bool match_index_to_operand(Node *operand, int indexcol,
                                           IndexOptInfo *index);
 extern List *expand_indexqual_conditions(IndexOptInfo *index,
index 5a9c2f2722488478ae3c951555441dec1ff9a3c9..527c5f500a56234a3d003cb1e1a9dbe2adff4b70 100644 (file)
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/optimizer/restrictinfo.h,v 1.32 2005/07/02 23:00:42 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/optimizer/restrictinfo.h,v 1.33 2005/07/28 20:26:22 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,7 +21,8 @@ extern RestrictInfo *make_restrictinfo(Expr *clause,
                                                                           bool is_pushed_down,
                                                                           Relids required_relids);
 extern List *make_restrictinfo_from_bitmapqual(Path *bitmapqual,
-                                                                                          bool is_pushed_down);
+                                                                                          bool is_pushed_down,
+                                                                                          bool include_predicates);
 extern bool restriction_is_or_clause(RestrictInfo *restrictinfo);
 extern List *get_actual_clauses(List *restrictinfo_list);
 extern void get_actual_join_clauses(List *restrictinfo_list,