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https://issues.apache.org/jira/browse/HBASE-14404?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14876786#comment-14876786
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Andrew Purtell commented on HBASE-14404:
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As a backport issue we are carrying back a change from later branches that
alter reader and writer behavior unconditionally. I can make it conditional
upon HBase settings changes but can't use the backport. It has to be a
different approach that looks at configuration where we set up the readers and
writers, rather than once in CacheConfig. Would no longer be a backport, but
instead something unique to 0.98. I don't think that's what we want. Since I
have a +1 to commit the earlier patch I'm going to drop the half-assed thing I
put up a few minutes ago and commit the original backport patch shortly.
> Backport HBASE-14098 (Allow dropping caches behind compactions) to 0.98
> -----------------------------------------------------------------------
>
> Key: HBASE-14404
> URL: https://issues.apache.org/jira/browse/HBASE-14404
> Project: HBase
> Issue Type: Task
> Reporter: Andrew Purtell
> Assignee: Andrew Purtell
> Fix For: 0.98.15
>
> Attachments: HBASE-14404-0.98.patch
>
>
> HBASE-14098 adds a new configuration toggle -
> "hbase.hfile.drop.behind.compaction" - which if set to "true" tells
> compactions to drop pages from the OS blockcache after write. It's on by
> default where committed so far but a backport to 0.98 would default it to
> off. (The backport would also retain compat methods to LimitedPrivate
> interface StoreFileScanner.) What could make it a controversial change in
> 0.98 is it changes the default setting of
> 'hbase.regionserver.compaction.private.readers' from "false" to "true". I
> think it's fine, we use private readers in production. They're stable and do
> not present perf issues.
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