From c2f0d565f319f7a75f0178758e9270c96d0c807f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 18 May 1999 21:36:10 +0000
Subject: [PATCH] Now that hashjoin is reliable for large joins (knock on
wood), remove optimizer's arbitrary limit on how large a join it will use
hashing for. (The limit was too large to prevent the problems we'd been
seeing, anyway...)
---
src/backend/optimizer/path/joinpath.c | 77 +++++++++++----------------
1 file changed, 30 insertions(+), 47 deletions(-)
diff --git a/src/backend/optimizer/path/joinpath.c b/src/backend/optimizer/path/joinpath.c
index 930112f888e..9bb890c6eb1 100644
--- a/src/backend/optimizer/path/joinpath.c
+++ b/src/backend/optimizer/path/joinpath.c
@@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.35 1999/05/16 19:45:37 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.36 1999/05/18 21:36:10 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -37,7 +37,6 @@ static List *match_unsorted_outer(RelOptInfo *joinrel, RelOptInfo *outerrel, Rel
List *mergeinfo_list);
static List *match_unsorted_inner(RelOptInfo *joinrel, RelOptInfo *outerrel, RelOptInfo *innerrel,
List *innerpath_list, List *mergeinfo_list);
-static bool EnoughMemoryForHashjoin(RelOptInfo *hashrel);
static List *hash_inner_and_outer(RelOptInfo *joinrel, RelOptInfo *outerrel, RelOptInfo *innerrel,
List *hashinfo_list);
@@ -490,27 +489,6 @@ match_unsorted_inner(RelOptInfo *joinrel,
return mp_list;
}
-static bool
-EnoughMemoryForHashjoin(RelOptInfo *hashrel)
-{
- int ntuples;
- int tupsize;
- int pages;
-
- ntuples = hashrel->size;
- if (ntuples == 0)
- ntuples = 1000;
- tupsize = hashrel->width + sizeof(HeapTupleData);
- pages = page_size(ntuples, tupsize);
-
- /*
- * if amount of buffer space below hashjoin threshold, return false
- */
- if (ceil(sqrt((double) pages)) > NBuffers)
- return false;
- return true;
-}
-
/*
* hash_inner_and_outer-- XXX HASH
* Create hashjoin join paths by explicitly hashing both the outer and
@@ -530,17 +508,17 @@ hash_inner_and_outer(RelOptInfo *joinrel,
RelOptInfo *innerrel,
List *hashinfo_list)
{
- HashInfo *xhashinfo = (HashInfo *) NULL;
List *hjoin_list = NIL;
- HashPath *temp_node = (HashPath *) NULL;
- List *i = NIL;
- List *outerkeys = NIL;
- List *innerkeys = NIL;
- List *hash_pathkeys = NIL;
+ List *i;
foreach(i, hashinfo_list)
{
- xhashinfo = (HashInfo *) lfirst(i);
+ HashInfo *xhashinfo = (HashInfo *) lfirst(i);
+ List *outerkeys;
+ List *innerkeys;
+ List *hash_pathkeys;
+ HashPath *temp_node;
+
outerkeys = make_pathkeys_from_joinkeys(
((JoinMethod *) xhashinfo)->jmkeys,
outerrel->targetlist,
@@ -549,26 +527,31 @@ hash_inner_and_outer(RelOptInfo *joinrel,
((JoinMethod *) xhashinfo)->jmkeys,
innerrel->targetlist,
INNER);
+ /* We cannot assume that the output of the hashjoin appears in any
+ * particular order, so it should have NIL pathkeys.
+ */
+#ifdef NOT_USED
hash_pathkeys = new_join_pathkeys(outerkeys,
joinrel->targetlist,
((JoinMethod *) xhashinfo)->clauses);
-
- if (EnoughMemoryForHashjoin(innerrel))
- {
- temp_node = create_hashjoin_path(joinrel,
- outerrel->size,
- innerrel->size,
- outerrel->width,
- innerrel->width,
- (Path *) outerrel->cheapestpath,
- (Path *) innerrel->cheapestpath,
- hash_pathkeys,
- xhashinfo->hashop,
- ((JoinMethod *) xhashinfo)->clauses,
- outerkeys,
- innerkeys);
- hjoin_list = lappend(hjoin_list, temp_node);
- }
+#else
+ hash_pathkeys = NIL;
+#endif
+
+ temp_node = create_hashjoin_path(joinrel,
+ outerrel->size,
+ innerrel->size,
+ outerrel->width,
+ innerrel->width,
+ (Path *) outerrel->cheapestpath,
+ (Path *) innerrel->cheapestpath,
+ hash_pathkeys,
+ xhashinfo->hashop,
+ ((JoinMethod *) xhashinfo)->clauses,
+ outerkeys,
+ innerkeys);
+ hjoin_list = lappend(hjoin_list, temp_node);
}
+
return hjoin_list;
}
--
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