mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-13 09:52:38 +00:00
43 lines
2.1 KiB
MySQL
43 lines
2.1 KiB
MySQL
|
-- Test that the optimizer picks up column statistics
|
||
|
|
-- (The concrete statistics type, column data type and predicate type don't matter)
|
||
|
|
|
||
|
|
-- Checks by the predicate evaluation order in EXPLAIN. This is quite fragile, a better approach would be helpful (maybe 'send_logs_level'?)
|
||
|
|
|
||
|
|
SET allow_experimental_statistics = 1;
|
||
|
|
SET allow_statistics_optimize = 1;
|
||
|
|
SET mutations_sync = 1;
|
||
|
|
SET enable_analyzer = 1;
|
||
|
|
|
||
|
|
DROP TABLE IF EXISTS tab;
|
||
|
|
|
||
|
|
CREATE TABLE tab
|
||
|
|
(
|
||
|
|
a Float64 STATISTICS(tdigest),
|
||
|
|
b Int64 STATISTICS(tdigest)
|
||
|
|
) Engine = MergeTree() ORDER BY tuple()
|
||
|
|
SETTINGS min_bytes_for_wide_part = 0;
|
||
|
|
|
||
|
|
INSERT INTO tab select number, -number FROM system.numbers LIMIT 10000;
|
||
|
|
SELECT 'After insert';
|
||
|
|
SELECT replaceRegexpAll(explain, '__table1\.', '') FROM (EXPLAIN actions=1 SELECT count(*) FROM tab WHERE b < 10 and a < 10) WHERE explain LIKE '%Prewhere%'; -- checks a first, then b (statistics used)
|
||
|
|
|
||
|
|
ALTER TABLE tab DROP STATISTICS a, b;
|
||
|
|
SELECT 'After drop statistic';
|
||
|
|
SELECT replaceRegexpAll(explain, '__table1\.', '') FROM (EXPLAIN actions=1 SELECT count(*) FROM tab WHERE b < 10 and a < 10) WHERE explain LIKE '%Prewhere%'; -- checks b first, then a (statistics not used)
|
||
|
|
|
||
|
|
ALTER TABLE tab ADD STATISTICS a, b TYPE tdigest;
|
||
|
|
ALTER TABLE tab MATERIALIZE STATISTICS a, b;
|
||
|
|
INSERT INTO tab select number, -number FROM system.numbers LIMIT 10000;
|
||
|
|
SELECT 'After add and materialize statistic';
|
||
|
|
SELECT replaceRegexpAll(explain, '__table1\.', '') FROM (EXPLAIN actions=1 SELECT count(*) FROM tab WHERE b < 10 and a < 10) WHERE explain LIKE '%Prewhere%'; -- checks a first, then b (statistics used)
|
||
|
|
|
||
|
|
OPTIMIZE TABLE tab FINAL;
|
||
|
|
SELECT 'After merge';
|
||
|
|
SELECT replaceRegexpAll(explain, '__table1\.', '') FROM (EXPLAIN actions=1 SELECT count(*) FROM tab WHERE b < 10 and a < 10) WHERE explain LIKE '%Prewhere%'; -- checks a first, then b (statistics used)
|
||
|
|
|
||
|
|
ALTER TABLE tab RENAME COLUMN b TO c;
|
||
|
|
SELECT 'After rename';
|
||
|
|
SELECT replaceRegexpAll(explain, '__table1\.', '') FROM (EXPLAIN actions=1 SELECT count(*) FROM tab WHERE c < 10 and a < 10) WHERE explain LIKE '%Prewhere%'; -- checks a first, then c (statistics used)
|
||
|
|
|
||
|
|
DROP TABLE IF EXISTS tab;
|