From 59fc64acee20071dd7386408c2e22a28e8c86541 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 11 Jan 2008 04:02:18 +0000
Subject: [PATCH] Fix a conceptual error in my patch of 2007-10-26 that avoided
considering clauseless joins of relations that have unexploited join clauses.
Rather than looking at every other base relation in the query, the correct
thing is to examine the other relations in the "initial_rels" list of the
current make_rel_from_joinlist() invocation, because those are what we
actually have the ability to join against. This might be a subset of the
whole query in cases where join_collapse_limit or from_collapse_limit or full
joins have prevented merging the whole query into a single join problem.
This is a bit untidy because we have to pass those rels down through a new
PlannerInfo field, but it's necessary. Per bug #3865 from Oleg Kharin.
---
src/backend/optimizer/path/allpaths.c | 7 +++++-
src/backend/optimizer/path/joinrels.c | 36 +++++++++++----------------
src/backend/optimizer/plan/planmain.c | 3 ++-
src/include/nodes/relation.h | 4 ++-
4 files changed, 26 insertions(+), 24 deletions(-)
diff --git a/src/backend/optimizer/path/allpaths.c b/src/backend/optimizer/path/allpaths.c
index 00e8d6f13fe..ef0b25bf5e2 100644
--- 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 1.167 2008/01/01 19:45:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/allpaths.c,v 1.168 2008/01/11 04:02:18 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -674,7 +674,12 @@ make_rel_from_joinlist(PlannerInfo *root, List *joinlist)
/*
* Consider the different orders in which we could join the rels,
* using a plugin, GEQO, or the regular join search code.
+ *
+ * We put the initial_rels list into a PlannerInfo field because
+ * has_legal_joinclause() needs to look at it (ugly :-().
*/
+ root->initial_rels = initial_rels;
+
if (join_search_hook)
return (*join_search_hook) (root, levels_needed, initial_rels);
else if (enable_geqo && levels_needed >= geqo_threshold)
diff --git a/src/backend/optimizer/path/joinrels.c b/src/backend/optimizer/path/joinrels.c
index 1287037c0ba..8df5c21f1fd 100644
--- a/src/backend/optimizer/path/joinrels.c
+++ b/src/backend/optimizer/path/joinrels.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.90 2008/01/01 19:45:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/path/joinrels.c,v 1.91 2008/01/11 04:02:18 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -838,33 +838,27 @@ has_join_restriction(PlannerInfo *root, RelOptInfo *rel)
* Detect whether the specified relation can legally be joined
* to any other rels using join clauses.
*
- * We consider only joins to single other relations. This is sufficient
- * to get a "true" result in most real queries, and an occasional erroneous
- * "false" will only cost a bit more planning time. The reason for this
- * limitation is that considering joins to other joins would require proving
- * that the other join rel can legally be formed, which seems like too much
- * trouble for something that's only a heuristic to save planning time.
+ * We consider only joins to single other relations in the current
+ * initial_rels list. This is sufficient to get a "true" result in most real
+ * queries, and an occasional erroneous "false" will only cost a bit more
+ * planning time. The reason for this limitation is that considering joins to
+ * other joins would require proving that the other join rel can legally be
+ * formed, which seems like too much trouble for something that's only a
+ * heuristic to save planning time. (Note: we must look at initial_rels
+ * and not all of the query, since when we are planning a sub-joinlist we
+ * may be forced to make clauseless joins within initial_rels even though
+ * there are join clauses linking to other parts of the query.)
*/
static bool
has_legal_joinclause(PlannerInfo *root, RelOptInfo *rel)
{
- Index rti;
+ ListCell *lc;
- for (rti = 1; rti < root->simple_rel_array_size; rti++)
+ foreach(lc, root->initial_rels)
{
- RelOptInfo *rel2 = root->simple_rel_array[rti];
+ RelOptInfo *rel2 = (RelOptInfo *) lfirst(lc);
- /* there may be empty slots corresponding to non-baserel RTEs */
- if (rel2 == NULL)
- continue;
-
- Assert(rel2->relid == rti); /* sanity check on array */
-
- /* ignore RTEs that are "other rels" */
- if (rel2->reloptkind != RELOPT_BASEREL)
- continue;
-
- /* ignore RTEs that are already in "rel" */
+ /* ignore rels that are already in "rel" */
if (bms_overlap(rel->relids, rel2->relids))
continue;
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c
index 9edd552138e..3776cf9b347 100644
--- a/src/backend/optimizer/plan/planmain.c
+++ b/src/backend/optimizer/plan/planmain.c
@@ -14,7 +14,7 @@
*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.105 2008/01/01 19:45:50 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/optimizer/plan/planmain.c,v 1.106 2008/01/11 04:02:18 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -142,6 +142,7 @@ query_planner(PlannerInfo *root, List *tlist,
root->right_join_clauses = NIL;
root->full_join_clauses = NIL;
root->oj_info_list = NIL;
+ root->initial_rels = NIL;
/*
* Make a flattened version of the rangetable for faster access (this is
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index f01f1e9e51f..b106c590e3e 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.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/nodes/relation.h,v 1.153 2008/01/09 20:42:28 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/relation.h,v 1.154 2008/01/11 04:02:18 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -165,6 +165,8 @@ typedef struct PlannerInfo
List *group_pathkeys; /* groupClause pathkeys, if any */
List *sort_pathkeys; /* sortClause pathkeys, if any */
+ List *initial_rels; /* RelOptInfos we are now trying to join */
+
MemoryContext planner_cxt; /* context holding PlannerInfo */
double total_table_pages; /* # of pages in all tables of query */
--
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