以下是我的聚合查询，需要 1.1 秒。该查询有多个联接。哪些列的索引将优化查询。
EXPLAIN SELECT straight_join
aggsm.tdm_id AS topid,
sum(aggsm.m_count) AS mencnt ,
sum(aggsm.ps_count) AS pscnt,
sum(aggsm.ns_count) AS ngscnt,
topdm.topic_name AS topname
FROM AGG_MENTION AS aggsm
JOIN TOPICDM AS topdm ON aggsm.topicdm_id = topdm.topicdm_id
JOIN LOCATIONDM AS locdm ON aggsm.locationdm_id = locdm.locationdm_id
JOIN CITY AS citydm ON locdm.city_id = citydm.city_id
JOIN STATE AS statedm ON citydm.state_id = statedm.state_id
WHERE aggsm.cdm_id = 11
AND aggsm.ei_type IN (1,2,3,4)
AND aggsm.datedm_id BETWEEN 20130101 AND 20130522
AND statedm.country_id IN (1,2,3,4)
AND topdm.topic_group_id IN (1,2,3,4,5,6,7)
GROUP BY aggsm.topicdm_id
-- ORDER BY aggsm.topicdm_id DESC,sum(aggsm.m_count) DESC
LIMIT 0,200000
以下是解释输出:
1 SIMPLE aggsm ref PRIMARY,datedm_id_UNIQUE,agg_sm_locdm_fk_idx,agg_sm_comdm_fk_idx,agg_sm_topdm_fk_idx,agg_sm_datedm_fk_idx,agg_em_indtype_fk_idx,comp_top_dt,l_idx comp_top_dt 8 const 202129 Using where; Using index
1 SIMPLE topdm eq_ref PRIMARY,topicdm_id_UNIQUE,topdm_grp_id_idx,id_idx PRIMARY 8 opinionleaders.aggsm.topicdm_id 1 Using where
1 SIMPLE locdm eq_ref PRIMARY,city_id_UNIQUE,locationdm_id_UNIQUE,loc_city_fk_idx,id_idx PRIMARY 8 opinionleaders.aggsm.locationdm_id 1
1 SIMPLE citydm eq_ref PRIMARY,city_id_UNIQUE,city_state_fk_idx,id_idx PRIMARY 8 opinionleaders.locdm.city_id 1
1 SIMPLE statedm eq_ref PRIMARY,state_id_UNIQUE,state_country_fk_idx,id_idx PRIMARY 8 opinionleaders.citydm.state_id 1 Using where
取消注释 order by 子句将导致 aggsm 表使用“using tempor,using filesort”
我们如何优化查询或定义索引
最佳答案
1) LIMIT 0,200000 绝对不是一个好的解决方案，我几乎看不到需要如此大量数据的应用程序，将其分成 block
2) 在 ORDER BY 子句中，您指定 sum(aggsm.m_count) - 这是一个聚合函数，尝试将其寻址为mencnt(因此ORDER BY aggsm.topicdm_id DESC，mencnt DESC)，不确定SQL Server是否按照您的意愿理解它
关于mysql - 优化聚合查询，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/16777958/