2012-03-20 15:37:55.907131+00:00 https://api.launchpad.net/1.0/bugs/921773 https://api.launchpad.net/1.0/~igorb-seattle https://api.launchpad.net/1.0/maria/+milestone/5.3 https://api.launchpad.net/1.0/bugs/921773/linked_branches https://api.launchpad.net/1.0/bugs/921773/activity https://bugs.launchpad.net/bugs/921773 Igor Babaev Igor Babaev Maria 5.3 In Progress Low 2012-01-25 19:39:03.874976+00:00 explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ The execution by this plan on a cold server took me 1 min 29.81 sec. However, when with the same settings the driving table is the table part and the execution plan is: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ an execution of the query takes significantly less time. The execution by this plan on a cold server took me 38.42 sec . A similar performance difference can be observed if to set the materialization flag of the optimizer switch to 'off'. The execution by the plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ took me 3 min 8.70 sec, while the execution by this plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ took me 50.25 sec. The current mysql 5.6 does not support materialization of subqueries, but it chooses the faster plan with the table part as the driving table.]]> bug Igor Babaev added bug maria: status Igor Babaev maria: importance Igor Babaev maria: assignee Igor Babaev maria: milestone Igor Babaev explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ The execution by this plan on a cold server took me 1 min 29.81 sec. However, when with the same settings the driving table is the table part and the execution plan is: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ an execution of the query takes significantly less time. The execution by this plan on a cold server took me 38.42 sec . A similar performance difference can be observed if to set the materialization flag of the optimizer switch to 'off'. The execution by the plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ took me 3 min 8.70 sec, while the execution by this plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ took me 50.25 sec. The current mysql 5.6 does not support materialization of subqueries, but it chooses the faster plan with the table part as the driving table.]]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ The execution by this plan on a cold server took me 1 min 29.81 sec. However, when with the same settings the driving table is the table part and the execution plan is: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ an execution of the query takes significantly less time. The execution by this plan on a cold server took me 38.42 sec . A similar performance difference can be observed if to set the materialization flag of the optimizer switch to 'off'. The execution by the plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ took me 3 min 8.70 sec, while the execution by this plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ took me 50.25 sec. The current mysql 5.6 does not support materialization of subqueries, but it chooses the faster plan with the table part as the driving table.]]> description Igor Babaev maria: status Igor Babaev maria: importance Michael Widenius Igor Babaev explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+--------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ The execution by this plan on a cold server took me 1 min 29.81 sec. However, when with the same settings the driving table is the table part and the execution plan is: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where | | 2 | MATERIALIZED | supplier | ALL | PRIMARY | NULL | NULL | NULL | 100000 | Using where | +----+--------------+----------+------+----------------------+--------------+---------+----------------------------------+---------+----------------------------------------------+ an execution of the query takes significantly less time. The execution by this plan on a cold server took me 38.42 sec . A similar performance difference can be observed if to set the materialization flag of the optimizer switch to 'off'. The execution by the plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | partsupp | index | PRIMARY,i_ps_partkey | PRIMARY | 8 | NULL | 8000000 | Using where; Using index; Using temporary; Using filesort | | 1 | PRIMARY | part | eq_ref | PRIMARY | PRIMARY | 4 | dbt3x10_myisam_56.partsupp.ps_partkey | 1 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+---------+---------+---------------------------------------+---------+---------------------------------------------------------------------------------+ took me 3 min 8.70 sec, while the execution by this plan: MariaDB [dbt3x10_myisam_56]> explain -> select sql_calc_found_rows -> p_brand, p_type, p_size, count(distinct ps_suppkey) as supplier_cnt -> from partsupp, part use index() -> where p_partkey = ps_partkey and p_brand <> 'Brand#45' -> and p_type not like 'MEDIUM POLISHED%'and p_size in -> (49, 14, 23, 45, 19, 3, 36, 9) -> and ps_suppkey not in (select s_suppkey from supplier -> where s_comment like '%Customer%Complaints%') -> group by p_brand, p_type, p_size -> order by supplier_cnt desc, p_brand, p_type, p_size -> limit 10; +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ | 1 | PRIMARY | part | ALL | NULL | NULL | NULL | NULL | 2000000 | Using where; Using temporary; Using filesort | | 1 | PRIMARY | partsupp | ref | PRIMARY,i_ps_partkey | i_ps_partkey | 4 | dbt3x10_myisam_56.part.p_partkey | 4 | Using where; Using join buffer (flat, BKA join); Key-ordered Rowid-ordered scan | | 2 | DEPENDENT SUBQUERY | supplier | unique_subquery | PRIMARY | PRIMARY | 4 | func | 1 | Using where | +----+--------------------+----------+-----------------+----------------------+--------------+---------+----------------------------------+---------+---------------------------------------------------------------------------------+ took me 50.25 sec. The current mysql 5.6 does not support materialization of subqueries, but it chooses the faster plan with the table part as the driving table.]]>