63 lines
2.2 KiB
Plaintext
63 lines
2.2 KiB
Plaintext
SET @query_cache_type= @@global.query_cache_type;
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SET @query_cache_limit= @@global.query_cache_limit;
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SET @query_cache_min_res_unit= @@global.query_cache_min_res_unit;
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SET @query_cache_size= @@global.query_cache_size;
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# Bug#28249 Query Cache returns wrong result with concurrent insert/ certain lock
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# Establish connections user1,user2,user3 (user=root)
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# Switch to connection user1
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SET GLOBAL query_cache_type=1;
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SET GLOBAL query_cache_limit=10000;
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SET GLOBAL query_cache_min_res_unit=0;
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SET GLOBAL query_cache_size= 100000;
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FLUSH TABLES;
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DROP TABLE IF EXISTS t1, t2;
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CREATE TABLE t1 (a INT);
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CREATE TABLE t2 (a INT);
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INSERT INTO t1 VALUES (1),(2),(3);
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# Switch to connection user2
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LOCK TABLE t2 WRITE;
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# Switch to connection user1
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# "send" the next select, "reap" the result later.
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# The select will be blocked by the write lock on the t1.
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SELECT *, (SELECT COUNT(*) FROM t2) FROM t1;
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# Switch to connection user3
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# Poll till the select of connection user1 is blocked by the write lock on t1.
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SELECT user,command,state,info FROM information_schema.processlist
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WHERE state = 'Locked'
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AND info = 'SELECT *, (SELECT COUNT(*) FROM t2) FROM t1';
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user command state info
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root Query Locked SELECT *, (SELECT COUNT(*) FROM t2) FROM t1
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INSERT INTO t1 VALUES (4);
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# Switch to connection user2
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UNLOCK TABLES;
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# Switch to connection user1
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# Collecting ("reap") the result from the previously blocked select.
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# The printing of the result (varies between 3 and 4 rows) set has to be suppressed.
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# Switch to connection user3
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# The next select enforces that effects of "concurrent_inserts" like the
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# record with a = 4 is missing in result sets can no more happen.
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SELECT 1 FROM t1 WHERE a = 4;
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1
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1
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# Switch to connection user1
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# The next result set must contain 4 rows.
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SELECT *, (SELECT COUNT(*) FROM t2) FROM t1;
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a (SELECT COUNT(*) FROM t2)
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1 0
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2 0
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3 0
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4 0
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RESET QUERY CACHE;
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SELECT *, (SELECT COUNT(*) FROM t2) FROM t1;
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a (SELECT COUNT(*) FROM t2)
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1 0
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2 0
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3 0
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4 0
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DROP TABLE t1,t2;
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# Switch to connection default + close connections user1,user2,user3
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SET GLOBAL query_cache_type= @query_cache_type;
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SET GLOBAL query_cache_limit= @query_cache_limit;
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SET GLOBAL query_cache_min_res_unit= @query_cache_min_res_unit;
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SET GLOBAL query_cache_size= @query_cache_size;
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