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Upgrade cost estimation for joins, per discussion with Bradley Baetz.

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Try to model the effect of rescanning input tuples in mergejoins;
account for JOIN_IN short-circuiting where appropriate.  Also, recognize
that mergejoin and hashjoin clauses may now be more than single operator
calls, so we have to charge appropriate execution costs.
This commit is contained in:
Tom Lane
2003-01-27 20:51:54 +00:00
parent b2773d4099
commit 70fba70430
10 changed files with 360 additions and 189 deletions
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13
src/backend/optimizer/path/joinpath.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.76 2003/01/20 18:54:50 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/joinpath.c,v 1.77 2003/01/27 20:51:51 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -774,13 +774,6 @@ hash_inner_and_outer(Query *root,
* We examine each restrictinfo clause known for the join to see
* if it is mergejoinable and involves vars from the two sub-relations
* currently of interest.
*
* Since we currently allow only plain Vars as the left and right sides
* of mergejoin clauses, this test is relatively simple. This routine
* would need to be upgraded to support more-complex expressions
* as sides of mergejoins. In theory, we could allow arbitrarily complex
* expressions in mergejoins, so long as one side uses only vars from one
* sub-relation and the other side uses only vars from the other.
*/
static List *
select_mergejoin_clauses(RelOptInfo *joinrel,
@ -835,7 +828,9 @@ select_mergejoin_clauses(RelOptInfo *joinrel,
continue; /* not mergejoinable */
/*
* Check if clause is usable with these input rels.
* Check if clause is usable with these input rels. All the vars
* needed on each side of the clause must be available from one or
* the other of the input rels.
*/
if (is_subseti(restrictinfo->left_relids, outerrel->relids) &&
is_subseti(restrictinfo->right_relids, innerrel->relids))