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MWL#89: Cost-based choice between Materialization and IN->EXISTS transformation
- Added more tests to the MWL#89 specific test, and made the test more modular.
- Updated test files.
- Fixed a memory leak.
- More comments.
mysql-test/r/subselect_mat.result:
- Updated the test file to reflect the new optimizer switches related to
materialized subquery execution.
- Added one extra test to test all cases that expose BUG#40037 (this is an old bug from 5.x).
- Updated the test result with correct results that expose BUG#40037.
mysql-test/t/subselect_mat.test:
- Updated the test file to reflect the new optimizer switches related to
materialized subquery execution.
- Added one extra test to test all cases that expose BUG#40037 (this is an old bug from 5.x).
- Updated the test result with correct results that expose BUG#40037.
sql/sql_select.cc:
Fixed a memory leak reported by Valgrind.
This commit is contained in:
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152
mysql-test/include/subselect_mat_cost.inc
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152
mysql-test/include/subselect_mat_cost.inc
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-- echo
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-- echo /* A. Subqueries in the SELECT clause. */
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explain
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select a1, a1 in (select b1 from t2 where b1 > '0') from t1;
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select a1, a1 in (select b1 from t2 where b1 > '0') from t1;
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-- echo
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explain
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select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0') from t1;
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select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0') from t1;
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-- echo
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explain
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select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0' and b1 < '9') from t1;
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select a1, a2, (a1, a2) in (select b1, b2 from t2 where b1 > '0' and b1 < '9') from t1;
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-- echo
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-- echo /*
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-- echo B. "Natural" examples of subqueries without grouping that
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-- echo cannot be flattened into semijoin.
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-- echo */
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explain
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select a1 from t1 where a1 in (select b2 from t2) or a2 < '9';
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select a1 from t1 where a1 in (select b2 from t2) or a2 < '9';
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-- echo
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explain
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select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0') or a2 < '9';
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select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0') or a2 < '9';
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-- echo UNION subqueries are currently limited to only use IN-TO-EXISTS.
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explain
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select a2 from t1 where a2 in (select b2 from t2 UNION select b3 from t2 as t3);
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select a2 from t1 where a2 in (select b2 from t2 UNION select b3 from t2 as t3);
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-- echo
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explain
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select a1 from t1 where a1 = '1 - 02' and a1 in (select max(b1) from t2 where b2 = '2 - 02');
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select a1 from t1 where a1 = '1 - 02' and a1 in (select max(b1) from t2 where b2 = '2 - 02');
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-- echo
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explain
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select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 order by b3);
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select a1, a2 from t1 where (a1, a2) in (select b1, b2 from t2 order by b3);
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-- echo
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-- echo /* C. Subqueries in the WHERE clause with GROUP BY. */
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explain
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select * from t1 where a1 in (select b1 from t2 where b1 > '0' group by b1);
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select * from t1 where a1 in (select b1 from t2 where b1 > '0' group by b1);
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-- echo
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explain
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select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2);
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select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2);
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-- echo
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explain
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select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2 having b2 < '2 - 04');
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select * from t1 where (a1, a2) in (select b1, b2 from t2 where b1 > '0' group by b1, b2 having b2 < '2 - 04');
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-- echo
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explain
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select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 group by b1, b2, b3);
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select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 group by b1, b2, b3);
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-- echo
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explain
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select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 where b3 = '3 - 02' group by b1, b2);
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select * from t1 where (a1, a2, a3) in (select b1, b2, b3 from t2 where b3 = '3 - 02' group by b1, b2);
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-- echo
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explain
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select * from t1 where (a1,a2,a3) in (select b1,b2,b3 from t2 where b1 = '1 - 01' group by b1,b2,b3);
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select * from t1 where (a1,a2,a3) in (select b1,b2,b3 from t2 where b1 = '1 - 01' group by b1,b2,b3);
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-- echo
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-- echo /*
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-- echo D. Subqueries for which materialization is not possible, and the
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-- echo optimizer reverts to in-to-exists.
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-- echo */
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# The first two cases are rejected during the prepare phase by the procedure
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# subquery_types_allow_materialization().
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explain
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select left(a1,7), left(a2,7) from t1_1024 where a1 in (select b1 from t2_1024 where b1 > '0') or a2 < '9';
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select left(a1,7), left(a2,7) from t1_1024 where a1 in (select b1 from t2_1024 where b1 > '0') or a2 < '9';
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explain
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select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select b1, b2 from t2_1024 where b1 > '0') or a2 < '9';
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select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select b1, b2 from t2_1024 where b1 > '0') or a2 < '9';
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-- echo
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# The following two subqueries return the result of a string function with a
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# blob argument, where the return type may be != blob. These are rejected during
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# cost-based optimization when attempting to create a temporary table.
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explain
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select left(a1,7), left(a2,7) from t1_1024 where a1 in (select substring(b1,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
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select left(a1,7), left(a2,7) from t1_1024 where a1 in (select substring(b1,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
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explain
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select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select substring(b1,1,1024), substring(b2,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
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select left(a1,7), left(a2,7) from t1_1024 where (a1,a2) in (select substring(b1,1,1024), substring(b2,1,1024) from t2_1024 where b1 > '0') or a2 < '9';
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-- echo
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-- echo
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-- echo /* E. Edge cases. */
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-- echo
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-- echo /* E.1 Both materialization and in_to_exists cannot be off. */
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set @save_optimizer_switch=@@optimizer_switch;
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set @@optimizer_switch = 'materialization=off,in_to_exists=off';
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--error ER_ILLEGAL_SUBQUERY_OPTIMIZER_SWITCHES
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select * from t1 where a1 in (select b1 from t2 where b1 > '0' group by b1);
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set @@optimizer_switch = @save_optimizer_switch;
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-- echo /* E.2 Outer query without tables, always uses IN-TO-EXISTS. */
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explain
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select '1 - 03' in (select b1 from t2 where b1 > '0');
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select '1 - 03' in (select b1 from t2 where b1 > '0');
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-- echo /* E.3 Subqueries without tables. */
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explain
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select a1 from t1 where a1 in (select '1 - 03') or a2 < '9';
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select a1 from t1 where a1 in (select '1 - 03') or a2 < '9';
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-- echo UNION subqueries are currently limited to only use IN-TO-EXISTS.
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explain
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select a1 from t1 where a1 in (select '1 - 03' UNION select '1 - 02');
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select a1 from t1 where a1 in (select '1 - 03' UNION select '1 - 02');
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-- echo /* E.4 optimize_cond detects FALSE where/having clause. */
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explain
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select a1 from t1 where a1 in (select b1 from t2 where b1 = b2 and b2 = '1 - 03' and b1 = '1 - 02' ) or a2 < '9';
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select a1 from t1 where a1 in (select b1 from t2 where b1 = b2 and b2 = '1 - 03' and b1 = '1 - 02' ) or a2 < '9';
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-- echo /* E.5 opt_sum_query detects no matching min/max row or substitutes MIN/MAX with a const. */
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-- echo TODO this test produces wrong result due to missing logic to handle the case
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-- echo when JOIN::optimize detects an empty subquery result.
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#explain
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#select a1 from t1 where a1 in (select max(b1) from t2);
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#select a1 from t1 where a1 in (select max(b1) from t2);
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-- echo
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#explain
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#select a1 from t1 where a1 in (select max(b1) from t2 where b1 = '7 - 02');
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#select a1 from t1 where a1 in (select max(b1) from t2 where b1 = '7 - 02');
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-- echo /* E.6 make_join_select detects impossible WHERE. *
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-- echo TODO
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-- echo /* E.7 constant optimization detects "no matching row in const table". */
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-- echo TODO
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-- echo /* E.8 Impossible WHERE noticed after reading const tables. */
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explain
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select '1 - 03' in (select b1 from t2 where b1 > '0' and b1 < '0');
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select '1 - 03' in (select b1 from t2 where b1 > '0' and b1 < '0');
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-- echo
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-- echo /* F. UPDATE/DELETE with subqueries. */
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-- echo
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-- echo TODO
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-- echo
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