[GitHub] [incubator-doris] Yao-MR edited a comment on issue #4788: [Proposal] Use Rollup's Aggregation Key as Rollup's Bucket Key

[GitBox <gi...@apache.org>]

Yao-MR edited a comment on issue #4788:
URL: https://github.com/apache/incubator-doris/issues/4788#issuecomment-716397086


   > > why not give the right to the user, and user can set the distribute key of rollup table, instead of the aggreate key, so that
   > > user can control the location of data, cause the aggreate key may improve the performance of bigmap union Scenes, but may not cause the improvement of performance in other Scenes
   > 
   > @Yao-MR This is more flexible, and I also plan to do as you say.
   > Later I'll provide user interface design, please review as you have time.
   > But I'm more curious about your real usage scenarios for `user can control the location of data`
   
   First, we can know that location of rollup table will not affect the data consistent, even if in the bitmap union scenarios,
   
   Second, the bucket key just control the data location,  and if user`s subquery hit the the rollup table, we can not know the follow useage of the rollup table, so can can just think the rollup table like the special 'base table', 
   so, like we can not refuse the use define bucket key,  the base table can have the user define bucket key, why not set the user define key as the bucket key, 
   
   one usage scenarios i know is that, the two rollup table have the same user define key, when the rollup table join on the same user define key, this will improve the performance of the join, which is same as the colocation join use the DISTRIBUTED BY HASH(`join key`) 
   
   
   


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