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Modify create_index regression test to avoid intermittent failures.

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We have been seeing intermittent buildfarm failures due to a query
sometimes not using an index-only scan plan, because a background
auto-ANALYZE prevented the table's all-visible bits from being set
immediately, thereby causing the estimated cost of an index-only scan
to go up considerably.  Adjust the test case so that a bitmap index scan is
preferred instead, which serves equally well for the purpose the test case
is actually meant for.  (Of course, it would be better to eliminate the
interference from auto-ANALYZE, but I see no low-risk way to do that,
so any such fix will have to be left for 9.3 or later.)
This commit is contained in:
Tom Lane 2012-04-25 22:57:48 -04:00
parent 9fa82c9809
commit d6d5f67b5b
2 changed files with 14 additions and 12 deletions
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20
src/test/regress/expected/create_index.out
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@ -2605,21 +2605,23 @@ DROP TABLE onek_with_null;
CREATE TABLE dupindexcols AS
SELECT unique1 as id, stringu2::text as f1 FROM tenk1;
CREATE INDEX dupindexcols_i ON dupindexcols (f1, id, f1 text_pattern_ops);
VACUUM ANALYZE dupindexcols;
ANALYZE dupindexcols;
EXPLAIN (COSTS OFF)
SELECT count(*) FROM dupindexcols
WHERE f1 > 'MA' and id < 1000 and f1 ~<~ 'YX';
QUERY PLAN
---------------------------------------------------------------------------------
WHERE f1 > 'WA' and id < 1000 and f1 ~<~ 'YX';
QUERY PLAN
---------------------------------------------------------------------------------------
Aggregate
-> Index Only Scan using dupindexcols_i on dupindexcols
Index Cond: ((f1 > 'MA'::text) AND (id < 1000) AND (f1 ~<~ 'YX'::text))
(3 rows)
-> Bitmap Heap Scan on dupindexcols
Recheck Cond: ((f1 > 'WA'::text) AND (id < 1000) AND (f1 ~<~ 'YX'::text))
-> Bitmap Index Scan on dupindexcols_i
Index Cond: ((f1 > 'WA'::text) AND (id < 1000) AND (f1 ~<~ 'YX'::text))
(5 rows)
SELECT count(*) FROM dupindexcols
WHERE f1 > 'MA' and id < 1000 and f1 ~<~ 'YX';
WHERE f1 > 'WA' and id < 1000 and f1 ~<~ 'YX';
count
-------
497
97
(1 row)

6
src/test/regress/sql/create_index.sql
View File

@ -865,10 +865,10 @@ DROP TABLE onek_with_null;
CREATE TABLE dupindexcols AS
SELECT unique1 as id, stringu2::text as f1 FROM tenk1;
CREATE INDEX dupindexcols_i ON dupindexcols (f1, id, f1 text_pattern_ops);
VACUUM ANALYZE dupindexcols;
ANALYZE dupindexcols;
EXPLAIN (COSTS OFF)
SELECT count(*) FROM dupindexcols
WHERE f1 > 'MA' and id < 1000 and f1 ~<~ 'YX';
WHERE f1 > 'WA' and id < 1000 and f1 ~<~ 'YX';
SELECT count(*) FROM dupindexcols
WHERE f1 > 'MA' and id < 1000 and f1 ~<~ 'YX';
WHERE f1 > 'WA' and id < 1000 and f1 ~<~ 'YX';