相似sql查询时间差距大 #6571
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相似sql查询时间差距大
#6571
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通过设置 is_report_success=true 获取到实际的各个算子的执行时间,具体方式参见:http://doris.apache.org/master/zh-CN/administrator-guide/running-profile.html |
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sql A:
SELECT BITMAP_UNION_COUNT(CASE WHEN flag = 1 THEN field_id END) AS cnt FROM tableA
sql B:
SELECT BITMAP_UNION_COUNT(field_id) AS cnt FROM tableA where flag = 1
tableA表对field_id做了预聚合,使用explain的使用,看两个Sql都是使用了预聚合
进行查询sqlA的执行时间是sqlB的6倍,求告知sqlA执行慢的原因
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