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From "Ashish Singhi (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-15205) Do not find the replication scope for every WAL#append()
Date Fri, 12 Feb 2016 09:20:18 GMT

    [ https://issues.apache.org/jira/browse/HBASE-15205?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15144298#comment-15144298
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Ashish Singhi commented on HBASE-15205:
---------------------------------------

bq. For which we have to disable and enable the table. So this should workout.
It need not. It is configurable with {{hbase.online.schema.update.enable}} by default it is
{{true}} which means we do not enable and disable the table by default on alter table command.
Irrespective of that on alter table command the HRegion constructor will be called and map
will be updated accordingly.

bq. Is there any chance that the replication scope of a table can be changed without using
the alter_table command?
AFAIK no other way it is possible.

> Do not find the replication scope for every WAL#append()
> --------------------------------------------------------
>
>                 Key: HBASE-15205
>                 URL: https://issues.apache.org/jira/browse/HBASE-15205
>             Project: HBase
>          Issue Type: Sub-task
>          Components: regionserver
>            Reporter: ramkrishna.s.vasudevan
>            Assignee: ramkrishna.s.vasudevan
>            Priority: Minor
>             Fix For: 2.0.0
>
>         Attachments: HBASE-15205.patch, HBASE-15205_1.patch, ScopeWALEdits.jpg, ScopeWALEdits_afterpatch.jpg
>
>
> After the byte[] and char[] the other top contributor for lot of GC (though it is only
2.86%) is the UTF_8.newDecoder.
> This happens because for every WAL append we try to calculate the replication scope associate
with the families associated with the TableDescriptor. I think per WAL append doing this is
very costly and creates lot of garbage. 



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