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1、以前统计总量pv,uv和各分类的pv,uv都这么写也就是 SELECT a.type,a.pv,a.uv FROM ( SELECT type,count(1) as pv,COUNT(distinct(uid))as uv FROM t1 WHERE dt='201410129' AND req_url like 'mbloglist?domain=100808&ajwvr=6%' group by type union all SELECT 'all' as type,count(1) as pv,COUNT(distinct(uid))as uv FROM t1 WHERE dt='201410129' AND req_url like 'mbloglist?domain=100808&ajwvr=6%' ) a 说明:distinct虽然写起来挺方便的,但是效率真的太差,建议永远不要用distinct 2、然后我们的语句就可以改为: SELECT a.type,sum(pv),count(uid) FROM ( SELECT type,count(1) as pv,uid FROM t1 WHERE dt='201410129' AND req_url like 'mbloglist?domain=100808&ajwvr=6%' group by uid,type union all SELECT 'all' as type,count(1) as pv,uid FROM t1 WHERE dt='201410129' AND req_url like 'mbloglist?domain=100808&ajwvr=6%' group by uid ) a group by type 这样虽然效率提高了些,而且我也一直这么用了,有段时间,但总感觉还是很不爽,总觉得没有发挥union all的功能 3、今天才发现,这group by 不能写在里面,真的严重影响效率,而且按照上面写job数量还多,果断需改: SELECT type,SUM(pv),count(uid) FROM ( SELECT a.type,sum(pv),uid FROM ( SELECT type,1 as pv,uid FROM t1 WHERE dt='201410129' AND req_url like 'mbloglist?domain=100808&ajwvr=6%' union all SELECT 'all' as type,1 as pv,uid FROM t1 WHERE dt='201410129' AND req_url like 'mbloglist?domain=100808&ajwvr=6%' ) a group by uid,type) b group by type 经测试,效率果然杠杠的