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HBase, mail # user - When does compaction actually occur?


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Re: When does compaction actually occur?
Amandeep Khurana 2012-06-01, 23:04
Tom,  

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?

-Amandeep
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