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From "Anoop Sam John (Jira)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-23355) Add a conf key to decide which operations can trigger prefetch
Date Tue, 03 Dec 2019 03:06:00 GMT

    [ https://issues.apache.org/jira/browse/HBASE-23355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16986570#comment-16986570

Anoop Sam John commented on HBASE-23355:

I believe the prefetch feature was added with intent to fetch it on Region open only.  When
we go through that old Jira it look so.  We have cache on write config which will govern caching
on flush. (This is kind of prefetch only). The new Jira will do the same for compaction also.
 So dont think we need new prefetchOnFlush also. This might be an overkill IMHO.

> Add a conf key to decide which operations can trigger prefetch
> --------------------------------------------------------------
>                 Key: HBASE-23355
>                 URL: https://issues.apache.org/jira/browse/HBASE-23355
>             Project: HBase
>          Issue Type: Improvement
>            Reporter: chenxu
>            Assignee: chenxu
>            Priority: Major
> Copy the comment from anoop under https://issues.apache.org/jira/browse/HBASE-23066?focusedCommentId=16984140&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#comment-16984140
> {quote}On a side note, (Not related to this issue) when we have cache on write ON as
well as prefetch also On, do we do the caching part for the flushed files twice? When it is
written, its already been added to cache. Later as part of HFile reader open, the prefetch
threads will again do a read and add to cache!
> {quote}
> It's better to have a conf key to decide which operations(flush, compaction, regionOpen,
bulkload) can trigger the prefetch. In this way, if cacheonwrite is enabled, we can exclude
the flush and compaction operations when doing prefetch.

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