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Fix compare_fuzzy_path_costs() to behave a bit more sanely. The original

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coding would ignore startup cost differences of less than 1% of the
estimated total cost; which was OK for normal planning but highly not OK
if a very small LIMIT was applied afterwards, so that startup cost becomes
the name of the game.  Instead, compare startup and total costs fuzzily
but independently.  This changes the plan selected for two queries in the
regression tests; adjust expected-output files for resulting changes in
row order.  Per reports from Dawid Kuroczko and Sam Mason.
REL8_1_STABLE
Tom Lane 21 years ago
parent 3758affc9b
commit 37c443eefd
6 changed files with 1506 additions and 1525 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 55
      src/backend/optimizer/util/pathnode.c
  2. 24
      src/test/regress/expected/geometry.out
  3. 24
      src/test/regress/expected/geometry_1.out
  4. 24
      src/test/regress/expected/geometry_2.out
  5. 1452
      src/test/regress/expected/join.out
  6. 1452
      src/test/regress/expected/join_1.out

55
src/backend/optimizer/util/pathnode.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.123 2005/07/15 17:09:25 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/util/pathnode.c,v 1.124 2005/07/22 19:12:01 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -98,60 +98,41 @@ compare_path_costs(Path *path1, Path *path2, CostSelector criterion)
static int
compare_fuzzy_path_costs(Path *path1, Path *path2, CostSelector criterion)
{
Cost fuzz;
/*
* The fuzz factor is set at one percent of the smaller total_cost,
* but not less than 0.01 cost units (just in case total cost is
* zero).
* We use a fuzz factor of 1% of the smaller cost.
*
* XXX does this percentage need to be user-configurable?
*/
fuzz = Min(path1->total_cost, path2->total_cost) * 0.01;
fuzz = Max(fuzz, 0.01);
if (criterion == STARTUP_COST)
{
if (Abs(path1->startup_cost - path2->startup_cost) > fuzz)
{
if (path1->startup_cost < path2->startup_cost)
return -1;
else
return +1;
}
if (path1->startup_cost > path2->startup_cost * 1.01)
return +1;
if (path2->startup_cost > path1->startup_cost * 1.01)
return -1;
/*
* If paths have the same startup cost (not at all unlikely),
* order them by total cost.
*/
if (Abs(path1->total_cost - path2->total_cost) > fuzz)
{
if (path1->total_cost < path2->total_cost)
return -1;
else
return +1;
}
if (path1->total_cost > path2->total_cost * 1.01)
return +1;
if (path2->total_cost > path1->total_cost * 1.01)
return -1;
}
else
{
if (Abs(path1->total_cost - path2->total_cost) > fuzz)
{
if (path1->total_cost < path2->total_cost)
return -1;
else
return +1;
}
if (path1->total_cost > path2->total_cost * 1.01)
return +1;
if (path2->total_cost > path1->total_cost * 1.01)
return -1;
/*
* If paths have the same total cost, order them by startup cost.
*/
if (Abs(path1->startup_cost - path2->startup_cost) > fuzz)
{
if (path1->startup_cost < path2->startup_cost)
return -1;
else
return +1;
}
if (path1->startup_cost > path2->startup_cost * 1.01)
return +1;
if (path2->startup_cost > path1->startup_cost * 1.01)
return -1;
}
return 0;
}

24
src/test/regress/expected/geometry.out
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@ -258,24 +258,24 @@ SELECT '' AS twenty, b.f1 / p.f1 AS rotation
twenty | rotation
--------+----------------------------------------------------------------------
| (0,-0),(-0.2,-0.2)
| (0.08,-0),(0,-0.56)
| (0.0651176557644,0),(0,-0.0483449262493)
| (-0,0.0828402366864),(-0.201183431953,0)
| (0.2,0),(0,0)
| (-0.1,-0.1),(-0.3,-0.3)
| (0.12,-0.28),(0.04,-0.84)
| (0.0976764836466,-0.0241724631247),(0.0325588278822,-0.072517389374)
| (-0.100591715976,0.12426035503),(-0.301775147929,0.0414201183432)
| (0.3,0),(0.1,0)
| (-0.25,-0.25),(-0.25,-0.35)
| (0.26,-0.7),(0.1,-0.82)
| (0.109762715209,-0.0562379754329),(0.0813970697055,-0.0604311578117)
| (-0.251479289941,0.103550295858),(-0.322485207101,0.0739644970414)
| (0.3,0.05),(0.25,0)
| (-0.3,-0.3),(-0.3,-0.3)
| (0.08,-0),(0,-0.56)
| (0.12,-0.28),(0.04,-0.84)
| (0.26,-0.7),(0.1,-0.82)
| (0.12,-0.84),(0.12,-0.84)
| (0.0651176557644,0),(0,-0.0483449262493)
| (0.0976764836466,-0.0241724631247),(0.0325588278822,-0.072517389374)
| (0.109762715209,-0.0562379754329),(0.0813970697055,-0.0604311578117)
| (0.0976764836466,-0.072517389374),(0.0976764836466,-0.072517389374)
| (-0,0.0828402366864),(-0.201183431953,0)
| (-0.100591715976,0.12426035503),(-0.301775147929,0.0414201183432)
| (-0.251479289941,0.103550295858),(-0.322485207101,0.0739644970414)
| (-0.301775147929,0.12426035503),(-0.301775147929,0.12426035503)
| (0.2,0),(0,0)
| (0.3,0),(0.1,0)
| (0.3,0.05),(0.25,0)
| (0.3,0),(0.3,0)
(20 rows)

24
src/test/regress/expected/geometry_1.out
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@ -258,24 +258,24 @@ SELECT '' AS twenty, b.f1 / p.f1 AS rotation
twenty | rotation
--------+----------------------------------------------------------------------
| (0,0),(-0.2,-0.2)
| (0.08,0),(0,-0.56)
| (0.0651176557644,0),(0,-0.0483449262493)
| (0,0.0828402366864),(-0.201183431953,0)
| (0.2,0),(0,0)
| (-0.1,-0.1),(-0.3,-0.3)
| (0.12,-0.28),(0.04,-0.84)
| (0.0976764836466,-0.0241724631247),(0.0325588278822,-0.072517389374)
| (-0.100591715976,0.12426035503),(-0.301775147929,0.0414201183432)
| (0.3,0),(0.1,0)
| (-0.25,-0.25),(-0.25,-0.35)
| (0.26,-0.7),(0.1,-0.82)
| (0.109762715209,-0.0562379754329),(0.0813970697055,-0.0604311578117)
| (-0.251479289941,0.103550295858),(-0.322485207101,0.0739644970414)
| (0.3,0.05),(0.25,0)
| (-0.3,-0.3),(-0.3,-0.3)
| (0.08,0),(0,-0.56)
| (0.12,-0.28),(0.04,-0.84)
| (0.26,-0.7),(0.1,-0.82)
| (0.12,-0.84),(0.12,-0.84)
| (0.0651176557644,0),(0,-0.0483449262493)
| (0.0976764836466,-0.0241724631247),(0.0325588278822,-0.072517389374)
| (0.109762715209,-0.0562379754329),(0.0813970697055,-0.0604311578117)
| (0.0976764836466,-0.072517389374),(0.0976764836466,-0.072517389374)
| (0,0.0828402366864),(-0.201183431953,0)
| (-0.100591715976,0.12426035503),(-0.301775147929,0.0414201183432)
| (-0.251479289941,0.103550295858),(-0.322485207101,0.0739644970414)
| (-0.301775147929,0.12426035503),(-0.301775147929,0.12426035503)
| (0.2,0),(0,0)
| (0.3,0),(0.1,0)
| (0.3,0.05),(0.25,0)
| (0.3,0),(0.3,0)
(20 rows)

24
src/test/regress/expected/geometry_2.out
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@ -258,24 +258,24 @@ SELECT '' AS twenty, b.f1 / p.f1 AS rotation
twenty | rotation
--------+----------------------------------------------------------------------
| (0,-0),(-0.2,-0.2)
| (0.08,-0),(0,-0.56)
| (0.0651176557644,0),(0,-0.0483449262493)
| (-0,0.0828402366864),(-0.201183431953,0)
| (0.2,0),(0,0)
| (-0.1,-0.1),(-0.3,-0.3)
| (0.12,-0.28),(0.04,-0.84)
| (0.0976764836466,-0.0241724631247),(0.0325588278822,-0.072517389374)
| (-0.100591715976,0.12426035503),(-0.301775147929,0.0414201183432)
| (0.3,0),(0.1,0)
| (-0.25,-0.25),(-0.25,-0.35)
| (0.26,-0.7),(0.1,-0.82)
| (0.109762715209,-0.0562379754329),(0.0813970697055,-0.0604311578117)
| (-0.251479289941,0.103550295858),(-0.322485207101,0.0739644970414)
| (0.3,0.05),(0.25,0)
| (-0.3,-0.3),(-0.3,-0.3)
| (0.08,-0),(0,-0.56)
| (0.12,-0.28),(0.04,-0.84)
| (0.26,-0.7),(0.1,-0.82)
| (0.12,-0.84),(0.12,-0.84)
| (0.0651176557644,0),(0,-0.0483449262493)
| (0.0976764836466,-0.0241724631247),(0.0325588278822,-0.072517389374)
| (0.109762715209,-0.0562379754329),(0.0813970697055,-0.0604311578117)
| (0.0976764836466,-0.072517389374),(0.0976764836466,-0.072517389374)
| (-0,0.0828402366864),(-0.201183431953,0)
| (-0.100591715976,0.12426035503),(-0.301775147929,0.0414201183432)
| (-0.251479289941,0.103550295858),(-0.322485207101,0.0739644970414)
| (-0.301775147929,0.12426035503),(-0.301775147929,0.12426035503)
| (0.2,0),(0,0)
| (0.3,0),(0.1,0)
| (0.3,0.05),(0.25,0)
| (0.3,0),(0.3,0)
(20 rows)

1452
src/test/regress/expected/join.out
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1452
src/test/regress/expected/join_1.out
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