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83 lines
2.8 KiB
Text
83 lines
2.8 KiB
Text
create table t2 (a int);
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insert into t2 values (1),(2),(3);
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create view v2 as select a from t2;
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flush status;
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select * from v2;
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a
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1
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2
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3
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show status like '%Created_tmp%';
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Variable_name Value
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Created_tmp_disk_tables 0
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Created_tmp_files 0
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Created_tmp_tables 0
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explain select * from v2;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t2 ALL NULL NULL NULL NULL 3
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select * from (select * from t2) T1;
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a
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1
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2
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3
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show status like '%Created_tmp%';
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Variable_name Value
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Created_tmp_disk_tables 0
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Created_tmp_files 0
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Created_tmp_tables 0
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explain select * from (select * from t2) T1;
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t2 ALL NULL NULL NULL NULL 3
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drop view v2;
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drop table t2;
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CREATE TABLE t1(a int);
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INSERT INTO t1 values(1),(2);
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CREATE TABLE t2(a int);
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INSERT INTO t2 values(1),(2);
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EXPLAIN SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);
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id select_type table type possible_keys key key_len ref rows Extra
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1 PRIMARY t1 ALL NULL NULL NULL NULL 2 Using where
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 test.t1.a 1
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2 MATERIALIZED t2 ALL NULL NULL NULL NULL 2 Using temporary
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truncate table performance_schema.events_statements_history_long;
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flush status;
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CREATE TABLE t3 SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a HAVING a > 1);
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# Performance schema should be the same as "Created_tmp_tables" variable below
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select sum(created_tmp_tables) from performance_schema.events_statements_history_long;
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sum(created_tmp_tables)
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2
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show status like '%Created_tmp%';
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Variable_name Value
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Created_tmp_disk_tables 0
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Created_tmp_files 0
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Created_tmp_tables 2
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drop table t3;
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EXPLAIN SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 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 PRIMARY t1 ALL NULL NULL NULL NULL 2
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1 PRIMARY <subquery2> eq_ref distinct_key distinct_key 4 func 1
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2 MATERIALIZED t2 ALL NULL NULL NULL NULL 2
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truncate table performance_schema.events_statements_history_long;
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flush status;
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CREATE TABLE t3 SELECT * FROM t1 WHERE a IN (SELECT * FROM t2 GROUP BY a);
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# Performance schema should be the same as "Created_tmp_tables" variable below
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select sum(created_tmp_tables) from performance_schema.events_statements_history_long;
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sum(created_tmp_tables)
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1
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show status like '%Created_tmp%';
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Variable_name Value
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Created_tmp_disk_tables 0
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Created_tmp_files 0
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Created_tmp_tables 1
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drop table t1,t2,t3;
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truncate table performance_schema.events_statements_history_long;
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flush status;
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# Performance schema should be the same as "Created_tmp_tables" variable below
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select sum(created_tmp_tables) from performance_schema.events_statements_history_long;
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sum(created_tmp_tables)
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0
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show status like '%Created_tmp%';
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Variable_name Value
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Created_tmp_disk_tables 0
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Created_tmp_files 0
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Created_tmp_tables 0
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