diff options
Diffstat (limited to 'src/backend/optimizer/path/costsize.c')
| -rw-r--r-- | src/backend/optimizer/path/costsize.c | 84 |
1 files changed, 48 insertions, 36 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 6cf8b2af4b5..fbdeea414c2 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -42,7 +42,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.91 2002/11/21 00:42:19 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.92 2002/11/30 00:08:16 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -819,7 +819,7 @@ cost_mergejoin(Path *path, Query *root, * 'outer_path' is the path for the outer relation * 'inner_path' is the path for the inner relation * 'restrictlist' are the RestrictInfo nodes to be applied at the join - * 'hashclauses' is a list of the hash join clause (always a 1-element list) + * 'hashclauses' are the RestrictInfo nodes to use as hash clauses * (this should be a subset of the restrictlist) */ void @@ -838,10 +838,8 @@ cost_hashjoin(Path *path, Query *root, double innerbytes = relation_byte_size(inner_path->parent->rows, inner_path->parent->width); long hashtablebytes = SortMem * 1024L; - RestrictInfo *restrictinfo; - Var *left, - *right; Selectivity innerbucketsize; + List *hcl; if (!enable_hashjoin) startup_cost += disable_cost; @@ -856,43 +854,57 @@ cost_hashjoin(Path *path, Query *root, run_cost += cpu_operator_cost * outer_path->parent->rows; /* - * Determine bucketsize fraction for inner relation. First we have to - * figure out which side of the hashjoin clause is the inner side. + * Determine bucketsize fraction for inner relation. We use the + * smallest bucketsize estimated for any individual hashclause; + * this is undoubtedly conservative. */ - Assert(length(hashclauses) == 1); - Assert(IsA(lfirst(hashclauses), RestrictInfo)); - restrictinfo = (RestrictInfo *) lfirst(hashclauses); - /* these must be OK, since check_hashjoinable accepted the clause */ - left = get_leftop(restrictinfo->clause); - right = get_rightop(restrictinfo->clause); - - /* - * Since we tend to visit the same clauses over and over when planning - * a large query, we cache the bucketsize estimate in the RestrictInfo - * node to avoid repeated lookups of statistics. - */ - if (VARISRELMEMBER(right->varno, inner_path->parent)) + innerbucketsize = 1.0; + foreach(hcl, hashclauses) { - /* righthand side is inner */ - innerbucketsize = restrictinfo->right_bucketsize; - if (innerbucketsize < 0) + RestrictInfo *restrictinfo = (RestrictInfo *) lfirst(hcl); + Var *left, + *right; + Selectivity thisbucketsize; + + Assert(IsA(restrictinfo, RestrictInfo)); + /* these must be OK, since check_hashjoinable accepted the clause */ + left = get_leftop(restrictinfo->clause); + right = get_rightop(restrictinfo->clause); + + /* + * First we have to figure out which side of the hashjoin clause is the + * inner side. + * + * Since we tend to visit the same clauses over and over when planning + * a large query, we cache the bucketsize estimate in the RestrictInfo + * node to avoid repeated lookups of statistics. + */ + if (VARISRELMEMBER(right->varno, inner_path->parent)) { - /* not cached yet */ - innerbucketsize = estimate_hash_bucketsize(root, right); - restrictinfo->right_bucketsize = innerbucketsize; + /* righthand side is inner */ + thisbucketsize = restrictinfo->right_bucketsize; + if (thisbucketsize < 0) + { + /* not cached yet */ + thisbucketsize = estimate_hash_bucketsize(root, right); + restrictinfo->right_bucketsize = thisbucketsize; + } } - } - else - { - Assert(VARISRELMEMBER(left->varno, inner_path->parent)); - /* lefthand side is inner */ - innerbucketsize = restrictinfo->left_bucketsize; - if (innerbucketsize < 0) + else { - /* not cached yet */ - innerbucketsize = estimate_hash_bucketsize(root, left); - restrictinfo->left_bucketsize = innerbucketsize; + Assert(VARISRELMEMBER(left->varno, inner_path->parent)); + /* lefthand side is inner */ + thisbucketsize = restrictinfo->left_bucketsize; + if (thisbucketsize < 0) + { + /* not cached yet */ + thisbucketsize = estimate_hash_bucketsize(root, left); + restrictinfo->left_bucketsize = thisbucketsize; + } } + + if (innerbucketsize > thisbucketsize) + innerbucketsize = thisbucketsize; } /* |