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From "Vladimir Rodionov (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-14326) HBase book: fix definition of max min size to compact
Date Thu, 27 Aug 2015 20:52:45 GMT

    [ https://issues.apache.org/jira/browse/HBASE-14326?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14717504#comment-14717504

Vladimir Rodionov commented on HBASE-14326:

In ExploringCompactionPolicy, which is default, both: *hbase.hstore.compaction.max.size* and
*hbase.hstore.compaction.min.size*  are applied to *selection* of files - not to a single
file, as described erroneously in HBase book. 

> HBase book: fix definition of max min size to compact
> -----------------------------------------------------
>                 Key: HBASE-14326
>                 URL: https://issues.apache.org/jira/browse/HBASE-14326
>             Project: HBase
>          Issue Type: Bug
>          Components: documentation
>            Reporter: Vladimir Rodionov
>             Fix For: 2.0.0
> I think we need to change wording/definition of these config parameters in HBase book,
they are misleading:
> {quote}
> hbase.hstore.compaction.min.size
> Description
> A StoreFile smaller than this size will always be eligible for minor compaction. HFiles
this size or larger are evaluated by hbase.hstore.compaction.ratio to determine if they are
eligible. Because this limit represents the "automatic include"limit for all StoreFiles smaller
than this value, this value may need to be reduced in write-heavy environments where many
StoreFiles in the 1-2 MB range are being flushed, because every StoreFile will be targeted
for compaction and the resulting StoreFiles may still be under the minimum size and require
further compaction. If this parameter is lowered, the ratio check is triggered more quickly.
This addressed some issues seen in earlier versions of HBase but changing this parameter is
no longer necessary in most situations. Default: 128 MB expressed in bytes.
> Default
> 134217728
> hbase.hstore.compaction.max.size
> Description
> A StoreFile larger than this size will be excluded from compaction. The effect of raising
hbase.hstore.compaction.max.size is fewer, larger StoreFiles that do not get compacted often.
If you feel that compaction is happening too often without much benefit, you can try raising
this value. Default: the value of LONG.MAX_VALUE, expressed in bytes.
> {quote}
> For details, see HBASE-14263.

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