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From Michael Segel <michael_se...@hotmail.com>
Subject Re: Hbase Quality Of Service: large standarad deviation in insert time while inserting same type of rows in Hbase
Date Wed, 25 Apr 2012 01:58:53 GMT
Have you thought about Garbage Collection?


Sent from my iPhone

On Apr 24, 2012, at 12:41 PM, "Skchaudhary" <schoudhary@ivp.in> wrote:

> I have a cluster Hbase set-up. In that I have 3 Region Servers. There is a
> table which has 27 Regions equally distributed among 3 Region servers--9
> regions per region server.
> Region server 1 has ---region 1-9 Region server 2 has ---region 10-18 Region
> server 3 has ---region 19-27
> Now when I start a program which inserts rows in region 1 and region 5 (both
> under Region Server-1) alternatively and on continuous basis, I see that the
> insert time for each row is not constant or consistent---there is a lot of
> variance or say standard deviation of insert time is quite large. Some times
> it takes 2 ms to insert a row, sometimes 3 ms,sometimes 1000 ms and
> sometimes even > 3000 ms.Even though data size in rows is equal.
> I understand that due to flushing and compaction of Regions the writes are
> blocked---but then it should not be blocked for larger span of time and the
> blockage time should be consistent for every flush/compaction (minor
> compaction).
> All in all every time flush and compaction occurs it should take nearly same
> time for each compaction and flush.
> For our application we need a consistent quality of service and if not
> perfect atleast we need a well visible boundary lines--like for each row
> insert it will take some 0 to 10 ms and not more than 10 ms(just an example)
> that even though minor compaction or flush occurs.
> Is there any setting/configuration which I should try?
> Any ideas of how to achieve it in Hbase.
> Any help would be really appreciated.
> Thanks in advance!!
> -- 
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