MySQL索引排查
那海蓝蓝 人气:0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.
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