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Fix thinko: cost_mergejoin must pay attention to which side of the

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mergeclause is which when extracting selectivity info.
This commit is contained in:
Tom Lane 2002-03-01 20:50:20 +00:00
parent ed6986d3eb
commit 54f7f62d4a
1 changed files with 29 additions and 14 deletions
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43
src/backend/optimizer/path/costsize.c
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@ -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 1.81 2002/03/01 06:01:19 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.82 2002/03/01 20:50:20 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -467,10 +467,11 @@ cost_sort(Path *path, Query *root,
}
/*
* Note: should we bother to assign a nonzero run_cost to reflect the
* overhead of extracting tuples from the sort result? Probably not
* worth worrying about.
* Also charge a small amount (arbitrarily set equal to operator cost)
* per extracted tuple.
*/
run_cost += cpu_operator_cost * tuples;
path->startup_cost = startup_cost;
path->total_cost = startup_cost + run_cost;
}
@ -567,11 +568,12 @@ cost_mergejoin(Path *path, Query *root,
Cost run_cost = 0;
Cost cpu_per_tuple;
RestrictInfo *firstclause;
Var *leftvar;
double outer_rows,
inner_rows;
double ntuples;
Selectivity leftscan,
rightscan;
Selectivity outerscansel,
innerscansel;
Path sort_path; /* dummy for result of cost_sort */
if (!enable_mergejoin)
@ -592,11 +594,24 @@ cost_mergejoin(Path *path, Query *root,
mergejoinscansel(root, (Node *) firstclause->clause,
&firstclause->left_mergescansel,
&firstclause->right_mergescansel);
leftscan = firstclause->left_mergescansel;
rightscan = firstclause->right_mergescansel;
outer_rows = outer_path->parent->rows * leftscan;
inner_rows = inner_path->parent->rows * rightscan;
leftvar = get_leftop(firstclause->clause);
Assert(IsA(leftvar, Var));
if (intMember(leftvar->varno, outer_path->parent->relids))
{
/* left side of clause is outer */
outerscansel = firstclause->left_mergescansel;
innerscansel = firstclause->right_mergescansel;
}
else
{
/* left side of clause is inner */
outerscansel = firstclause->right_mergescansel;
innerscansel = firstclause->left_mergescansel;
}
outer_rows = outer_path->parent->rows * outerscansel;
inner_rows = inner_path->parent->rows * innerscansel;
/* cost of source data */
@ -616,13 +631,13 @@ cost_mergejoin(Path *path, Query *root,
outer_path->parent->width);
startup_cost += sort_path.startup_cost;
run_cost += (sort_path.total_cost - sort_path.startup_cost)
* leftscan;
* outerscansel;
}
else
{
startup_cost += outer_path->startup_cost;
run_cost += (outer_path->total_cost - outer_path->startup_cost)
* leftscan;
* outerscansel;
}
if (innersortkeys) /* do we need to sort inner? */
@ -635,13 +650,13 @@ cost_mergejoin(Path *path, Query *root,
inner_path->parent->width);
startup_cost += sort_path.startup_cost;
run_cost += (sort_path.total_cost - sort_path.startup_cost)
* rightscan;
* innerscansel;
}
else
{
startup_cost += inner_path->startup_cost;
run_cost += (inner_path->total_cost - inner_path->startup_cost)
* rightscan;
* innerscansel;
}
/*