Adar Dembo has posted comments on this change. ( 
http://gerrit.cloudera.org:8080/14107 )

Change subject: KUDU-2921: Exposing the table statistics to spark relation.
......................................................................


Patch Set 2:

> Actually, I have considered to put those statistics into existing message 
> such as getShema which will be used when opening table. But as for the table 
> statistics may contain more and more entries it may be better to be a 
> independent rpc. What's more, because this statistics may change when client 
> trying to write, so I think it will be useful to support a rpc for client to 
> get the statistics change. Although for query plan it will only use once and 
> save one round trip if we put it into existing rpc but it will be heavy if we 
> want to get statistic change in other use cases.

How are the stats useful for a writing client (i.e. an Impala or Spark 
executor) vs. the query planner?

What are the other use cases you're thinking about? If they're hypothetical, we 
could add the stats to GetTableLocations now, and also expose them via new RPC 
later, when those other use cases materialize.

>  > If doing this, let's make sure to make it optional, since the
>  > statistics could become larger later (eg with things like
>  > histograms, NDVs per column, etc)
>
> Will make it optional if do that :)

Agreed.


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Gerrit-Project: kudu
Gerrit-Branch: master
Gerrit-MessageType: comment
Gerrit-Change-Id: I7742a76708f989b0ccc8ba417f3390013e260175
Gerrit-Change-Number: 14107
Gerrit-PatchSet: 2
Gerrit-Owner: ZhangYao <triplesheep0...@gmail.com>
Gerrit-Reviewer: Adar Dembo <a...@cloudera.com>
Gerrit-Reviewer: Andrew Wong <aw...@cloudera.com>
Gerrit-Reviewer: Grant Henke <granthe...@apache.org>
Gerrit-Reviewer: Hao Hao <hao....@cloudera.com>
Gerrit-Reviewer: Kudu Jenkins (120)
Gerrit-Reviewer: Tidy Bot (241)
Gerrit-Reviewer: Todd Lipcon <t...@apache.org>
Gerrit-Reviewer: ZhangYao <triplesheep0...@gmail.com>
Gerrit-Comment-Date: Thu, 22 Aug 2019 18:58:36 +0000
Gerrit-HasComments: No

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