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HBase >> mail # user >> Major Compaction in 0.90.6


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Re: Major Compaction in 0.90.6
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J-D
On Mon, Aug 19, 2013 at 2:48 AM, Monish r <[EMAIL PROTECTED]> wrote:

> Hi guys,
> I have the following questions in HBASE 0.90.6
>
> 1. Does hbase use only one compaction thread to handle both major and minor
> compaction?
>

Yes, look at CompactSplitThread
>
> 2. If hbase uses multiple compaction threads, which configuration parameter
> defines the number of compaction threads?
>

It doesn't in 0.90.6 but CompactSplitThread lists those for 0.92+

hbase.regionserver.thread.compaction.large
hbase.regionserver.thread.compaction.small
>
> 3. After hbase.majorcompaction.interval from last major compaction ,if
> major compaction is executed on a table already major compacted Does hbase
> skip all the table regions from major compaction?
>

Determining if something is major-compacted is definitely not at the
table-level.

In 0.90.6, MajorCompactionChecker will ask HRegion.isMajorCompaction() to
check if it needs to major compact again, which in turns checks every
Store. FWW if you have TTL turned on it will still major compact a major
compacted file, HFiles don't have an index of what's deleted or TTL'd and
it doesn't do a full read of each files to check.
>
> Regards,
> R.Monish
>