[jira] [Commented] (KUDU-3430) Get flags in old version of Kudu may fail

["Alexey Serbin (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KUDU-3430?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17676371#comment-17676371 ] 

Alexey Serbin commented on KUDU-3430:
-------------------------------------

If https://github.com/apache/kudu/commit/2f8778c40edd0114777054a7c2a6b79cc6949f56 introduced a introduced a proper feature flag so the server could tell the client right away it doesn't support filtering, there would be no such a strange behavior, I guess.

The server-side filtering approach has a benefit of transferring less data between the server and the client.

As of current, I'd like to point that a hybrid approach is possible.  It will work as expected against all server-side versions.  The idea is to rely on the server-side filtering for the newer releases (1.12.0 and newer) and do the client-side filtering if working with servers of earlier releases (1.11.1 and older).  There is a way to get the versioning information from Kudu servers in the CLI tools: see the {{GetStatus}} RPC and how it's used in {{ksck_remote.cc}}.  Also, there is {{ParseVersion()}} utility function in {{version_utils.\{h,cc\}}} to help with parsing Kudu version string into a tuple that can be used in comparisons used by the semantic versioning model.

> Get flags in old version of Kudu may fail
> -----------------------------------------
>
>                 Key: KUDU-3430
>                 URL: https://issues.apache.org/jira/browse/KUDU-3430
>             Project: Kudu
>          Issue Type: Bug
>            Reporter: Xixu Wang
>            Priority: Major
>             Fix For: 1.16.0
>
>         Attachments: image-2022-12-29-11-46-52-376.png, image-2022-12-30-09-20-43-149.png, screenshot-1.png
>
>
> When using new version of Kudu tool (version: 1.16.0) to execute command: _{color:#ff0000}kudu tserver get_flags localhost:7050 -flags=block_cache_capacity_mb{color}_ in old version of Kudu TServer (version: 1.10.1)，it returned all flags not the specified flags.
> !image-2022-12-30-09-20-43-149.png!
>  
> That because the filter logic was not implemented in server side (Kudu version 1.10.1).
> !image-2022-12-29-11-46-52-376.png!
>  
> So it is better to implement the filter logic in Kudu tool side not Kudu server side.



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