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Adjust costsize calculations to avoid introducing unnecessary roundoff

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error.  This seems to explain the differing choice of plan that's been
causing geometry regress test to fail for the last few days.
This commit is contained in:
Tom Lane 2002-12-13 17:29:25 +00:00
parent 023ff17178
commit 77b7a740f9
1 changed files with 42 additions and 18 deletions
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60
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 1.94 2002/12/12 15:49:28 tgl Exp $
* $Header: /cvsroot/pgsql/src/backend/optimizer/path/costsize.c,v 1.95 2002/12/13 17:29:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -672,12 +672,22 @@ cost_nestloop(Path *path, Query *root,
*/
startup_cost += outer_path->startup_cost + inner_path->startup_cost;
run_cost += outer_path->total_cost - outer_path->startup_cost;
run_cost += outer_path->parent->rows *
(inner_path->total_cost - inner_path->startup_cost);
if (!(IsA(inner_path, MaterialPath) ||
IsA(inner_path, HashPath)) &&
outer_path->parent->rows > 1)
run_cost += (outer_path->parent->rows - 1) * inner_path->startup_cost;
if (IsA(inner_path, MaterialPath) ||
IsA(inner_path, HashPath))
{
/* charge only run cost for each iteration of inner path */
run_cost += outer_path->parent->rows *
(inner_path->total_cost - inner_path->startup_cost);
}
else
{
/*
* charge total cost for each iteration of inner path, except we
* already charged the first startup_cost in our own startup
*/
run_cost += outer_path->parent->rows * inner_path->total_cost
- inner_path->startup_cost;
}
/*
* Number of tuples processed (not number emitted!). If inner path is
@ -768,8 +778,8 @@ cost_mergejoin(Path *path, Query *root,
innerscansel = firstclause->left_mergescansel;
}
outer_rows = outer_path->parent->rows * outerscansel;
inner_rows = inner_path->parent->rows * innerscansel;
outer_rows = ceil(outer_path->parent->rows * outerscansel);
inner_rows = ceil(inner_path->parent->rows * innerscansel);
/* cost of source data */
@ -1343,10 +1353,12 @@ approx_selectivity(Query *root, List *quals)
void
set_baserel_size_estimates(Query *root, RelOptInfo *rel)
{
double temp;
/* Should only be applied to base relations */
Assert(length(rel->relids) == 1);
rel->rows = rel->tuples *
temp = rel->tuples *
restrictlist_selectivity(root,
rel->baserestrictinfo,
lfirsti(rel->relids));
@ -1354,10 +1366,14 @@ set_baserel_size_estimates(Query *root, RelOptInfo *rel)
/*
* Force estimate to be at least one row, to make explain output look
* better and to avoid possible divide-by-zero when interpolating
* cost.
* cost. Make it an integer, too.
*/
if (rel->rows < 1.0)
rel->rows = 1.0;
if (temp < 1.0)
temp = 1.0;
else
temp = ceil(temp);
rel->rows = temp;
rel->baserestrictcost = cost_qual_eval(rel->baserestrictinfo);
@ -1437,10 +1453,12 @@ set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
/*
* Force estimate to be at least one row, to make explain output look
* better and to avoid possible divide-by-zero when interpolating
* cost.
* cost. Make it an integer, too.
*/
if (temp < 1.0)
temp = 1.0;
else
temp = ceil(temp);
rel->rows = temp;
@ -1470,6 +1488,8 @@ set_joinrel_size_estimates(Query *root, RelOptInfo *rel,
void
set_function_size_estimates(Query *root, RelOptInfo *rel)
{
double temp;
/* Should only be applied to base relations that are functions */
Assert(length(rel->relids) == 1);
Assert(rel->rtekind == RTE_FUNCTION);
@ -1483,7 +1503,7 @@ set_function_size_estimates(Query *root, RelOptInfo *rel)
rel->tuples = 1000;
/* Now estimate number of output rows */
rel->rows = rel->tuples *
temp = rel->tuples *
restrictlist_selectivity(root,
rel->baserestrictinfo,
lfirsti(rel->relids));
@ -1491,10 +1511,14 @@ set_function_size_estimates(Query *root, RelOptInfo *rel)
/*
* Force estimate to be at least one row, to make explain output look
* better and to avoid possible divide-by-zero when interpolating
* cost.
* cost. Make it an integer, too.
*/
if (rel->rows < 1.0)
rel->rows = 1.0;
if (temp < 1.0)
temp = 1.0;
else
temp = ceil(temp);
rel->rows = temp;
rel->baserestrictcost = cost_qual_eval(rel->baserestrictinfo);