我在具有许多嵌套in子句的查询中面临速度缓慢。
查询如下：
select SA0_.sid as stid from table_starea SA0_ left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid where SA0_.sid in (select SB1_.sid from table_arstaff AC0_ left outer join table_stf SB1_ on AC0_.sid=SB1_.sid left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid where AC0_.acid in (select AC1_.acid from table_starea SA0_ left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid where SA0_.sid in (select SB1_.sid from table_arstaff AC0_ left outer join table_stf SB1_ on AC0_.sid=SB1_.sid left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid where AC0_.acid in (select AC1_.acid from table_starea SA0_ left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid where SA0_.sid in (select SB1_.sid from table_arstaff AC0_ left outer join table_stf SB1_ on AC0_.sid=SB1_.sid left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid where AC0_.acid in (select AC1_.acid from table_starea SA0_ left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid where SA0_.sid in (select SB1_.sid from table_arstaff AC0_ left outer join table_stf SB1_ on AC0_.sid=SB1_.sid left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid where AC0_.acid in (select AC1_.acid from table_starea SA0_ left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid where SA0_.sid in (select SB1_.sid from table_arstaff AC0_ left outer join table_stf SB1_ on AC0_.sid=SB1_.sid left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid where AC0_.acid in (select AC1_.acid from table_starea SA0_ left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid where SA0_.sid in (select SB1_.sid from table_arstaff AC0_ left outer join table_stf SB1_ on AC0_.sid=SB1_.sid left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid where AC0_.acid=19)))))))))));
我检查了解释，发现如下：
+----+--------------+-------------------+------------+------------+----------------------------------------+---------------------+---------+----------------------------------------------------+------+----------+--------------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+--------------+-------------------+------------+------------+----------------------------------------+---------------------+---------+----------------------------------------------------+------+----------+--------------------------+
| 1 | SIMPLE | <subquery2> | NULL | ALL | NULL | NULL | NULL | NULL | NULL | 100.00 | Using where |
| 1 | SIMPLE | SA0_ | NULL | ref | table_starea_ix01 | table_starea_ix01 | 5 | <subquery2>.sid | 1 | 100.00 | Using index |
| 1 | SIMPLE | AC1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SA0_.acid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | AC0_ | NULL | ref | table_arstaff_ix01,tab_attach_fk2 | table_arstaff_ix01 | 4 | const | 4 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | SB1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.AC0_.sid | 1 | 100.00 | NULL |
| 2 | MATERIALIZED | SG2_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SB1_.sgid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | SA0_ | NULL | ref | FKFA890976F203761F,table_starea_ix01 | table_starea_ix01 | 5 | ain2013Realdb.AC0_.sid | 1 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | AC1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SA0_.acid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | AC0_ | NULL | ref | table_arstaff_ix01,tab_attach_fk2 | table_arstaff_ix01 | 4 | ain2013Realdb.SA0_.acid | 2 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | SB1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.AC0_.sid | 1 | 100.00 | NULL |
| 2 | MATERIALIZED | SG2_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SB1_.sgid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | SA0_ | NULL | ref | FKFA890976F203761F,table_starea_ix01 | table_starea_ix01 | 5 | ain2013Realdb.AC0_.sid | 1 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | AC1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SA0_.acid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | AC0_ | NULL | ref | table_arstaff_ix01,tab_attach_fk2 | table_arstaff_ix01 | 4 | ain2013Realdb.SA0_.acid | 2 | 100.00 | Using index |
| 2 | MATERIALIZED | SB1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.AC0_.sid | 1 | 100.00 | NULL |
| 2 | MATERIALIZED | SG2_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SB1_.sgid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | SA0_ | NULL | ref | FKFA890976F203761F,table_starea_ix01 | table_starea_ix01 | 5 | ain2013Realdb.AC0_.sid | 1 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | AC1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SA0_.acid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | AC0_ | NULL | ref | table_arstaff_ix01,tab_attach_fk2 | table_arstaff_ix01 | 4 | ain2013Realdb.SA0_.acid | 2 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | SB1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.AC0_.sid | 1 | 100.00 | NULL |
| 2 | MATERIALIZED | SG2_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SB1_.sgid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | SA0_ | NULL | ref | FKFA890976F203761F,table_starea_ix01 | table_starea_ix01 | 5 | ain2013Realdb.AC0_.sid | 1 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | AC1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SA0_.acid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | AC0_ | NULL | ref | table_arstaff_ix01,tab_attach_fk2 | table_arstaff_ix01 | 4 | ain2013Realdb.SA0_.acid | 2 | 100.00 | Using index |
| 2 | MATERIALIZED | SB1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.AC0_.sid | 1 | 100.00 | NULL |
| 2 | MATERIALIZED | SG2_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SB1_.sgid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | SA0_ | NULL | ref | FKFA890976F203761F,table_starea_ix01 | table_starea_ix01 | 5 | ain2013Realdb.AC0_.sid | 1 | 100.00 | Using where; Using index |
| 2 | MATERIALIZED | AC1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SA0_.acid | 1 | 100.00 | Using index |
| 2 | MATERIALIZED | AC0_ | NULL | ref | table_arstaff_ix01,tab_attach_fk2 | table_arstaff_ix01 | 4 | ain2013Realdb.SA0_.acid | 2 | 100.00 | Using index |
| 2 | MATERIALIZED | SB1_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.AC0_.sid | 1 | 100.00 | NULL |
| 2 | MATERIALIZED | SG2_ | NULL | eq_ref | PRIMARY | PRIMARY | 4 | ain2013Realdb.SB1_.sgid | 1 | 100.00 | Using index |
+----+--------------+-------------------+------------+------------+----------------------------------------+---------------------+---------+----------------------------------------------------+------+----------+--------------------------+
有人可以提出解决方案以使此查询快速执行吗？
我使用INNER JOIN重写了查询，如下所示：
从table_starea中选择SA0_.sid作为stid SA0_在SA0_.acid = AC1_.acid上从左外部加入table_arcons AC1_，其中SA0_.sid在（从（（从table_arstaff AC0_选择SB1_.sid，AC0_.acid在AC0_.sid = SB1_.sid上连接table_stf SB1_在SB1_.sgid = SG2_.sgid上左外部连接table_stfgr SG2_）TAB19 INNER JOIN（从（（从table_starea SA0_中选择AC1_.acid，SA0_.sid选择酸）（从table_starea SA0_选择左酸）在SA0_.acid = AC1_.acid上）TAB17 INNER JOIN（从（（从table_arstaff中选择SB1_.sid，AC0_.acid，从AC0_.sid = SB1_.sid在SB1_上的左外部连接table_stf SB1_中选择sid。 sgid = SG2_.sgid）TAB15内联接（从（（从table_starea SA0_左SA2_左外联接table_arcons AC1_在SA0_.acid = AC1_.acid上选择AC1_.acid，SA0_.sid中选择酸）TAB13 INNER JOIN（从（（选择sid SB1_.sid，来自table_arstaff的AC0_.acid AC0_左外部联接table_stf AC0_.sid = SB1_.sid左外部联接table_stfgr SG2_ SB1_.sgid = SG2_.sgid）TAB11 INNER JOIN（从（（从table_starea SA0_选择左AC1_.acid，SA0_.sid从table_starea SA0_.acid = AC1_.acid上选择AC1_。酸，SA0_.sid）选择酸）TAB9 INNER JOIN（从（（从选择（SB1_.sid，AC0_.acid从table_arstaff AC0_在AC0_.sid = SB1_.sid上的左外部连接table_stf SB1_。在SB1_.sgid = SG2_.sgid上的左外部连接table_stfgr SG2_）TAB7 INNER JOIN（从（（从table_starea SA0中选择AC1_.acid，SA0_.sid_左外部联接table_arcons SA1_上的AC1_.acid = AC1_.acid）TAB5内部联接（从（选择SB1_.sid中选择sid，从table_arstaff AC0_中选择AC0_.acid AC0_左外部联接table_stf在AC0_.sid = SB1_.sid上的SB1_左外部联接table_stfgrgr SB1_.sgid = SG2_.sgid上的SG2_）TAB3内联接（从（选择AC1_.acid，从table_starea SA0_左SA2_左外联接table_arcons AC1_在SA0_.acid = AC1_.acid上选择酸）TAB2内联接（选择SB1_。来自table_arstaff AC0_的sid，位于AC0_.sid = SB1_.sid的左外部联接table_stf SB1_。位于SB1_.sgid = SG2_.sgid的左外部联接table_stfgr SG2_，其中AC0_.acid = 19） TAB1 ON TAB2.sid = TAB1.sid）TAB4 on TAB3.acid = TAB4.acid）TAB6 on TAB5.sid = TAB6.sid））TAB8 ON TAB7.acid = TAB8.acid））TAB10 on TAB9.sid = TAB10。 sid））TAB11.acid上的TAB12 = TAB12.acid））TAB13.sid上的TAB14 = TAB14.sid））TAB15.acid上的TAB16 = TAB16.acid）））TAB17.sid上的TAB18 = TAB18.sid））TAB19上的TAB20 .acid = TAB20.acid））;
这会带来优化吗？
答案 0 :(得分：0)
关于性能的第一条建议..每个IN子句都可以轻松更改大多数性能的INNER JOIN子句，例如，对于更深层的嵌套级别，您可以更改代码
....
select AC1_.acid
from table_starea SA0_
left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid
where SA0_.sid in (
select SB1_.sid
from table_arstaff AC0_
left outer join table_stf SB1_ on AC0_.sid=SB1_.sid
left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid
where AC0_.acid=19 )
....)))))))));
与
......
select AC1_.acid
from table_starea SA0_
left outer join table_arcons AC1_ on SA0_.acid=AC1_.acid
) t2 on AC0_.acid = t2.acid
INNER JOIN (
select SB1_.sid
from table_arstaff AC0_
left outer join table_stf SB1_ on AC0_.sid=SB1_.sid
left outer join table_stfgr SG2_ on SB1_.sgid=SG2_.sgid
where AC0_.acid=19
) t1 on t1.sid = SA0_.sid
....)))))))));
resul相同，但是内部联接应该更快。
您可以从更深层次的代码开始重构代码，并一一对应地重构所有具有相应INNER JOIN的IN子句