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From Mehdi Ben Haj Abbes <mehdi.ab...@gmail.com>
Subject Re: When compactions become major ones
Date Tue, 05 Jan 2016 16:39:33 GMT
Thanks Ted for the clarification about the major compactions. So if I did
understand well when a minor compaction is triggered and the policy selects
all the store files, this compaction becomes a major one. But would this
minor which becomes major take care of deleted rows as a major one would do
or at the end it is just a minor that happened and selected all the store
files ?

About disabling splitting I have already hbase.hregion.max.filesize set to
10GB besides I pre splitted my table.

And I still dont understand how the store files resulting after memstore
flushes are having a size of 40MB. Does it hove smth to do with memstore
upper limit and these 42MB are the result of forcing the memstore to be
flushed? The problem is that all the newly store files added to HDFS are
starting with this size (42MB) I did not mention that my CF is in-memory.

Best regards,

On Tue, Jan 5, 2016 at 4:04 PM, Ted Yu <yuzhihong@gmail.com> wrote:

> For #1, when all store files are selected for compaction, the compaction
> becomes major
> see 'Determine the Optimal Number of Pre-Split Regions' under:
> http://hbase.apache.org/book.html#disable.splitting
> See also http://hbase.apache.org/book.html#managed.compactions
> Cheers
> On Tue, Jan 5, 2016 at 6:52 AM, Mehdi Ben Haj Abbes <mehdi.abbes@gmail.com
> >
> wrote:
> > Hi folks,
> >
> > I'm using hbase 0.98. I have heavy writes workload. I'm writing to one
> > table with one CF compressed with GZ. My table is pre splitted to 27
> > regions. As I start writing to this table I start seeing HFiles of the
> size
> > of 2-4 MB across the regions. I have the default hbase configuration for
> > compaction properties. The compactions start as soon as I start writing
> to
> > HBase but many of these compaction are major ones. I can see this through
> > HBase master UI on the table details view. So I wanted to understand
> when a
> > compaction becomes major.
> >
> > Another question, If I'm not wrong we have a memstore per region, so
> when a
> > memstore is flushed I will have a HFile with 128MB but I only see files
> > with 42MB (without compression and 2.5MB when compressed with GZ).
> >
> > Any explanation ?
> >
> > Thanks in advance.
> > --
> >


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