41 lines
2.2 KiB
SQL
41 lines
2.2 KiB
SQL
--echo # 'Using index' method is used since wild string is suitable for the use with prefix key.
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'a%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'ab%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'abcd%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'abc\%%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '\%abc%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'abc%%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '%%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '____%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '\_\_\_\_%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '\%\%\%\%';
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EXPLAIN SELECT b LIKE 'abcd' FROM t1 WHERE b like 'ab%';
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EXPLAIN SELECT b LIKE 'abc%' FROM t1 WHERE b like 'ab%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'aaa\\';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'aaa\\\\';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'aaa\\\\%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'a_';
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--echo # 'Using index' method is not used since wild string is not suitable for the use with prefix key.
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like '%a';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'a%c%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'a%c';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'abcde%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'abcde%';
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EXPLAIN SELECT b FROM t1 WHERE b like 'ab%';
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EXPLAIN SELECT b LIKE 'abcde' FROM t1 WHERE b like 'ab%';
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EXPLAIN SELECT b LIKE '%bc' FROM t1 WHERE b like 'ab%';
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'aaaa\\';
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--echo # 'Using index' method is not used since wild string is not suitable for the use with prefix key.
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'a%' OR b like '%a';
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--echo # 'Using index' method is used since wild string is suitable for the use with prefix key.
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EXPLAIN SELECT COUNT(*) FROM t1 WHERE b like 'ab%';
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--echo # 'Using index' method is not used since 'b' field is used in select output.
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EXPLAIN SELECT b FROM t1 WHERE b like 'ab%';
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--echo # Index k2 shouldn't be used.
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EXPLAIN SELECT COUNT(*) FROM t1 IGNORE INDEX(k2) WHERE b like 'a%';
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