[jira] [Assigned] (KUDU-1808) Simplify KuduSession mutation buffer/flush watermark pct API

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

     [ https://issues.apache.org/jira/browse/KUDU-1808?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alexey Serbin reassigned KUDU-1808:
-----------------------------------

    Assignee: Alexey Serbin

> Simplify KuduSession mutation buffer/flush watermark pct API
> ------------------------------------------------------------
>
>                 Key: KUDU-1808
>                 URL: https://issues.apache.org/jira/browse/KUDU-1808
>             Project: Kudu
>          Issue Type: Improvement
>          Components: client
>    Affects Versions: 1.0.0
>            Reporter: Matthew Jacobs
>            Assignee: Alexey Serbin
>
> The API to configure the KuduSession memory is very confusing. It's not obvious how to pick good values for {{SetMutationBufferSpace()}}, {{SetMutationBufferMaxNum()}}, and {{SetMutationBufferFlushWatermark()}}.  My understanding is that a user might:
> * pick some amount of memory _M_ to be used for the mutation buffer space, though this isn't obvious (high values increase throughput, but too high and the writes may overwhelm tservers)
> * set the flush watermark pct to (1/_NumBuffers_) where _NumBuffers_ = ( _M_ / 7MB) , and where 7MB is Kudu's internal  buffer size
>   (formula from [~tlipcon])
> * Set SetMutationBufferMaxNum(0) since the max buffers wouldn't be necessary.
> This is what Impala does at the moment, but this is very complicated.



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