Hi： I am having an issue regarding the process of targeting the correct segment of a cube. The issue is as below:
I have a cube built daily using the parttion field “DAY”, so the cube has the following segments: 20180101000000_20180102000000 20180102000000_20180103000000 … 20180929000000_20180930000000 When I submit a query with the filter: where “DAY” = 20180101, Kylin starts to look for the correct segment from the very beginning and after it targets the right segment, it continues the looking process until the end of all the segments. The logic works but it significantly downgrade the query performance. The following is the timeline summarized from the log: 13:54:00,951 start 13:54:00,975 finish cube selection (24ms) 13:54:01,004 query storage 13:54:01,019 target the right segment (44ms) 13:54:01,021 looking for other segments 13:54:01,423 finish looking for other segments (402ms) 13:54:01,431 return the result (8ms) total: 478ms looking for other segments (402ms) Therefore, most of the time was wasted in looking for the unnecessary segments, which was 402ms. Then I have a few questions regarding this: 1. When it targeted the right segment, why the segment looking process doesn’t stop? 2. Even if it stops after targeting the right segment, the performance will still be bad if the needed segment is at the end of the segment span. 3. It’s known that every segment is stored as a separate Hbase table, why can’t it target the right hbase table immediately if there are some mappings from segments to table names? Many thanks for the reply and I really appreciate your help! Best, Feng. 发送自 Windows 10 版邮件<https://go.microsoft.com/fwlink/?LinkId=550986>应用
