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EXPLAIN EXTENDED warning.
Query optimizer searches for the constant tables and optimizes them away. This
means that fields of such tables are substituted for their values and on later
phases they are treated as constants. After this constant tables are removed
from the query execution plan. Nevertheless constant tables were shown in
the EXPLAIN EXTENDED warning thus producing query that might be not an
equivalent of the original query.
Now the print_join function skips all tables that were optimized away from
printing to the EXPLAIN EXTENDED warning. If all tables were optimized away it
produces the 'FROM dual' clause.
mysql-test/r/explain.result:
A test case added for the bug#30302.
mysql-test/r/func_default.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/func_regexp.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/func_test.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/having.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/select.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/subselect.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/subselect3.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/r/type_datetime.result:
Adjusted test case result after fix for the bug#30302.
mysql-test/t/explain.test:
A test case added for the bug#30302.
sql/sql_select.cc:
Bug#30302: Tables that were optimized away are printed in the
EXPLAIN EXTENDED warning.
Now the print_join function skips all tables that were optimized away from
printing to the EXPLAIN EXTENDED warning. If all tables were optimized away it
produces the 'FROM dual' clause.
sql/table.h:
Adjusted test case result after fix for the bug#30302.
The optimized_away flag is added to the TABLE_LIST struct.
23 lines
1.2 KiB
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23 lines
1.2 KiB
Text
drop table if exists t1,t2;
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create table t1(str varchar(10) default 'def',strnull varchar(10),intg int default '10',rel double default '3.14');
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insert into t1 values ('','',0,0.0);
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select default(str), default(strnull), default(intg), default(rel) from t1;
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default(str) default(strnull) default(intg) default(rel)
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def NULL 10 3.14
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explain extended select default(str), default(strnull), default(intg), default(rel) from t1;
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id select_type table type possible_keys key key_len ref rows filtered Extra
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1 SIMPLE t1 system NULL NULL NULL NULL 1 100.00
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Warnings:
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Note 1003 select default('') AS `default(str)`,default('') AS `default(strnull)`,default('0') AS `default(intg)`,default('0') AS `default(rel)` from dual
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select * from t1 where str <> default(str);
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str strnull intg rel
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0 0
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explain select * from t1 where str <> default(str);
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id select_type table type possible_keys key key_len ref rows Extra
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1 SIMPLE t1 system NULL NULL NULL NULL 1
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drop table t1;
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CREATE TABLE t1 (id int(11), s varchar(20));
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INSERT INTO t1 VALUES (1, 'one'), (2, 'two'), (3, 'three');
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SELECT s, 32 AS mi FROM t1 GROUP BY s HAVING DEFAULT(mi) IS NULL;
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ERROR HY000: Field 'mi' doesn't have a default value
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DROP TABLE t1;
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