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46 lines
1.3 KiB
Plaintext
46 lines
1.3 KiB
Plaintext
drop table if exists t1,t2;
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#
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# Bug#50939: Loose Index Scan unduly relies on engine to remember range
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# endpoints
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#
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CREATE TABLE t1 (
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a INT,
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b INT,
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KEY ( a, b )
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) PARTITION BY HASH (a) PARTITIONS 1;
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CREATE TABLE t2 (
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a INT,
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b INT,
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KEY ( a, b )
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);
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INSERT INTO t1 VALUES (1, 1), (2, 2), (3, 3), (4, 4), (5, 5);
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INSERT INTO t1 SELECT a + 5, b + 5 FROM t1;
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INSERT INTO t1 SELECT a + 10, b + 10 FROM t1;
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INSERT INTO t1 SELECT a + 20, b + 20 FROM t1;
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INSERT INTO t1 SELECT a + 40, b + 40 FROM t1;
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INSERT INTO t2 SELECT * FROM t1;
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# plans should be identical
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EXPLAIN SELECT a, MAX(b) FROM t1 WHERE a IN (10,100) GROUP BY a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 range a a 5 NULL 2 Using where; Using index
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EXPLAIN SELECT a, MAX(b) FROM t2 WHERE a IN (10,100) GROUP BY a;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t2 range a a 5 NULL 2 Using where; Using index
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FLUSH status;
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SELECT a, MAX(b) FROM t1 WHERE a IN (10, 100) GROUP BY a;
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a MAX(b)
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10 10
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# Should be no more than 4 reads.
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SHOW status LIKE 'handler_read_key';
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Variable_name Value
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Handler_read_key 2
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FLUSH status;
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SELECT a, MAX(b) FROM t2 WHERE a IN (10, 100) GROUP BY a;
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a MAX(b)
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10 10
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# Should be no more than 4 reads.
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SHOW status LIKE 'handler_read_key';
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Variable_name Value
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Handler_read_key 2
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DROP TABLE t1, t2;
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