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HBase, mail # user - Tables gets Major Compacted even if they haven't changed


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Re: Tables gets Major Compacted even if they haven't changed
lars hofhansl 2013-09-11, 02:12
That. And other parameters (like compression) might have been changed, too. Would need to check for that as well,
________________________________
 From: Dave Latham <[EMAIL PROTECTED]>
To: [EMAIL PROTECTED]; lars hofhansl <[EMAIL PROTECTED]>
Sent: Tuesday, September 10, 2013 11:11 AM
Subject: Re: Tables gets Major Compacted even if they haven't changed
 
Major compactions can still be useful to improve locality - could we add a condition to check for that too?
On Mon, Sep 9, 2013 at 10:41 PM, lars hofhansl <[EMAIL PROTECTED]> wrote:

Interesting. I guess we could add a check to avoid major compactions if (1) no TTL is set or we can show that all data is newer and (2) there's only one file (3) and there are no delete markers. All of these can be cheaply checked with some HFile metadata (we might have all data needed already).
>
>
>That would take care of both of your scenarios.
>
>-- Lars
>________________________________
>From: Premal Shah <[EMAIL PROTECTED]>
>To: user <[EMAIL PROTECTED]>
>Sent: Monday, September 9, 2013 9:02 PM
>
>Subject: Tables gets Major Compacted even if they haven't changed
>
>
>
>Hi,
>We have a bunch on tables in our HBase cluster. We have a script which
>makes sure all of them get Major Compacted once every 2 days. There are 2
>things I'm observing
>
>1) Table X has not updated in a month. We have not inserted, updated or
>deleted data. However, it still major compacts every 2 days. All the
>regions in this table have only 1 store file.
>
>2) Table Y has a few regions where the rowkey is essentially a timestamp.
>So, we only write to 1 region at a time. Over time, the region splits, and
>then we write the one of the split regions. Now, whenever we major compact
>the table, all regions get major compacted. Only 1 region has more than 1
>store file, every other region has exactly once.
>
>Is there a way to avoid compaction of regions that have not changed?
>
>We are using HBase 0.94.11
>
>--
>Regards,
>Premal Shah.
>