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Prevent (auto)vacuum from truncating first page of populated matview.

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Per report from Fujii Masao, with regression test using his example.
This commit is contained in:
Kevin Grittner 2013-05-02 17:33:03 -05:00
parent 095018bc32
commit b69ec7cc99
3 changed files with 38 additions and 0 deletions
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6
src/backend/commands/vacuumlazy.c
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@ -230,7 +230,13 @@ lazy_vacuum_rel(Relation onerel, VacuumStmt *vacstmt,
* *
* Don't even think about it unless we have a shot at releasing a goodly * Don't even think about it unless we have a shot at releasing a goodly
* number of pages. Otherwise, the time taken isn't worth it. * number of pages. Otherwise, the time taken isn't worth it.
*
* Leave a populated materialized view with at least one page.
*/ */
if (onerel->rd_rel->relkind == RELKIND_MATVIEW &&
vacrelstats->nonempty_pages == 0)
vacrelstats->nonempty_pages = 1;
possibly_freeable = vacrelstats->rel_pages - vacrelstats->nonempty_pages; possibly_freeable = vacrelstats->rel_pages - vacrelstats->nonempty_pages;
if (possibly_freeable > 0 && if (possibly_freeable > 0 &&
(possibly_freeable >= REL_TRUNCATE_MINIMUM || (possibly_freeable >= REL_TRUNCATE_MINIMUM ||

20
src/test/regress/expected/matview.out
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@ -418,3 +418,23 @@ NOTICE: drop cascades to 3 other objects
DETAIL: drop cascades to view v_test2 DETAIL: drop cascades to view v_test2
drop cascades to materialized view mv_test2 drop cascades to materialized view mv_test2
drop cascades to materialized view mv_test3 drop cascades to materialized view mv_test3
-- test that vacuum does not make empty matview look unpopulated
CREATE TABLE hoge (i int);
INSERT INTO hoge VALUES (generate_series(1,100000));
CREATE MATERIALIZED VIEW hogeview AS SELECT * FROM hoge WHERE i % 2 = 0;
CREATE INDEX hogeviewidx ON hogeview (i);
DELETE FROM hoge;
REFRESH MATERIALIZED VIEW hogeview;
SELECT * FROM hogeview WHERE i < 10;
i
---
(0 rows)
VACUUM ANALYZE;
SELECT * FROM hogeview WHERE i < 10;
i
---
(0 rows)
DROP TABLE hoge CASCADE;
NOTICE: drop cascades to materialized view hogeview

12
src/test/regress/sql/matview.sql
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@ -129,3 +129,15 @@ CREATE MATERIALIZED VIEW mv_test3 AS SELECT * FROM mv_test2 WHERE moo = 12345;
SELECT pg_relation_is_scannable('mv_test3'::regclass); SELECT pg_relation_is_scannable('mv_test3'::regclass);
DROP VIEW v_test1 CASCADE; DROP VIEW v_test1 CASCADE;
-- test that vacuum does not make empty matview look unpopulated
CREATE TABLE hoge (i int);
INSERT INTO hoge VALUES (generate_series(1,100000));
CREATE MATERIALIZED VIEW hogeview AS SELECT * FROM hoge WHERE i % 2 = 0;
CREATE INDEX hogeviewidx ON hogeview (i);
DELETE FROM hoge;
REFRESH MATERIALIZED VIEW hogeview;
SELECT * FROM hogeview WHERE i < 10;
VACUUM ANALYZE;
SELECT * FROM hogeview WHERE i < 10;
DROP TABLE hoge CASCADE;