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43 lines
2.1 KiB
MySQL
43 lines
2.1 KiB
MySQL
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-- Test that the optimizer picks up column statistics
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-- (The concrete statistics type, column data type and predicate type don't matter)
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-- Checks by the predicate evaluation order in EXPLAIN. This is quite fragile, a better approach would be helpful (maybe 'send_logs_level'?)
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SET allow_experimental_statistics = 1;
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SET allow_statistics_optimize = 1;
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SET mutations_sync = 1;
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SET enable_analyzer = 1;
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DROP TABLE IF EXISTS tab;
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CREATE TABLE tab
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(
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a Float64 STATISTICS(tdigest),
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b Int64 STATISTICS(tdigest)
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) Engine = MergeTree() ORDER BY tuple()
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SETTINGS min_bytes_for_wide_part = 0;
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INSERT INTO tab select number, -number FROM system.numbers LIMIT 10000;
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SELECT 'After insert';
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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)
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ALTER TABLE tab DROP STATISTICS a, b;
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SELECT 'After drop statistic';
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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)
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ALTER TABLE tab ADD STATISTICS a, b TYPE tdigest;
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ALTER TABLE tab MATERIALIZE STATISTICS a, b;
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INSERT INTO tab select number, -number FROM system.numbers LIMIT 10000;
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SELECT 'After add and materialize statistic';
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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)
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OPTIMIZE TABLE tab FINAL;
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SELECT 'After merge';
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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)
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ALTER TABLE tab RENAME COLUMN b TO c;
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SELECT 'After rename';
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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)
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DROP TABLE IF EXISTS tab;
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