早上收到开发同学求助，有个SQL查询耗时特别长，看了执行计划发现没有走索引，但是不知道原因在哪里，我们一起来分析一下。
mysql>explain SELECT * FROM artisan_income WHERE parent_id IN ( 222645481, 222583953, 222181775, 222180931, 222081126, 221678753, 221616102, 221591783, 221219312, 221195482, 221118672, 220763129, 220654289, 220633930, 220323633, 220227641, 219825564, 219720338, 219321345, 219291958 ) \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: artisan_income partitions: type: ALL possible_keys: idx_parent_id key: key_len: ref: rows: 20711352 filtered: 100 Extra: Using where
确实是全表扫描，带着疑问我们把生产环境数据同步到测试库，方便测试，然后在测试环境进行查询。
mysql>explain SELECT * FROM artisan_income WHERE parent_id IN ( 222645481, 222583953, 222181775, 222180931, 222081126, 221678753, 221616102, 221591783, 221219312, 221195482, 221118672, 220763129, 220654289, 220633930, 220323633, 220227641, 219825564, 219720338, 219321345, 219291958 ) \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: artisan_income partitions: type: range possible_keys: idx_parent_id key: idx_parent_id key_len: 5 ref: rows: 1870780 filtered: 100 Extra: Using index condition
发现在测试环境就用到了parent_id字段的索引，生产库和测试库同样都是5.7的版本，数据也几乎一样，但是执行计划不一样，第一时间想到了统计信息的问题，于是进行analyze table
analyze table artisan_income;
然后查看执行计划：
mysql>explain SELECT * FROM artisan_income WHERE parent_id IN ( 222645481, 222583953, 222181775, 222180931, 222081126, 221678753, 221616102, 221591783, 221219312, 221195482, 221118672, 220763129, 220654289, 220633930, 220323633, 220227641, 219825564, 219720338, 219321345, 219291958 ) \G *************************** 1. row *************************** id: 1 select_type: SIMPLE table: artisan_income partitions: type: range possible_keys: idx_parent_id key: idx_parent_id key_len: 5 ref: rows: 1901880 filtered: 100 Extra: Using index condition
发现执行计划已经恢复正常。
mysql>SELECT * FROM artisan_income WHERE parent_id IN ( 222645481, 222583953, 222181775, 222180931, 222081126, 221678753, 221616102, 221591783, 221219312, 221195482, 221118672, 220763129, 220654289, 220633930, 220323633, 220227641, 219825564, 219720338, 219321345, 219291958 ) \G 返回行数：[0]，耗时：2 ms.