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Code Issues Releases Wiki Activity

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...)
This commit is contained in:
Tom Lane 1999-05-18 21:36:10 +00:00
parent 353d36f979
commit c2f0d565f3
1 changed files with 29 additions and 46 deletions
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75
src/backend/optimizer/path/joinpath.c
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@ -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);
#else
hash_pathkeys = NIL;
#endif
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);
}
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;
}