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From Amandeep Khurana <ama...@gmail.com>
Subject Re: When does compaction actually occur?
Date Fri, 01 Jun 2012 23:04:32 GMT

Old cells will get deleted as a part of the next major compaction, which is typically recommended
to be done once a day, when the load on the system is at its lowest.

FWIW… To have a TTL of 3600 take effect, you'll have to do a major compaction every hour,
which is an expensive operation specially at scale. Chances are that your I/O loads will shoot
up and latencies will spike for operations to HBase. Can you tell us why a TTL of 3600s is
of interest? What are your access patterns?


On Friday, June 1, 2012 at 3:59 PM, Tom Brown wrote:

> I have a table that holds rotating data. It has a TTL of 3600. For
> some reason, when I scan the table I still get old cells that are much
> older than that TTL.
> I have tried issuing a compaction request via the web UI, but that
> didn't seem to do anything.
> Am I misunderstanding the data model used by HBase? Is there anything
> else I can check to verify the functionality of my integration?
> I am using HBase 0.92 with Hadoop 1.0.2.
> Thanks in advance!
> --Tom  

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