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From Tyler Hobbs <ty...@datastax.com>
Subject Re: Question regarding tombstone removal and compaction
Date Sat, 11 Aug 2012 22:14:01 GMT
On Fri, Aug 10, 2012 at 5:54 AM, Fredrik
<fredrik.l.stigback@sitevision.se>wrote:

> We've had a bug that caused one of our column families to grow very big
> 280 GB on a 500 GB disk. We're using size tiered compaction.
> Since it's "only append" data I've now issued deletes of 260 GB of
> superflous data.
>
> 1. There are som quite large SSTables (80 GB, 40 GB etc..). If I run a
> major compaction before GC grace, which is 6 hours, will the compaction
> succeed or will it fail due to the GC grace hasn't elapsed and thus major
> compaction will ignore the tombstones and then fail due to insufficient
> disk space?
>

The major compaction would fail, because the tombstones could not be purged
yet.


>
> 2. If I wait until GC grace has elapsed, will it be possible to run a
> major compaction since there are only deletes which doesn't require double
> amount of SStable size when merging tombstones with the large SSTables?
>

Yes, although it's a better idea to let minor compactions take care of that.

-- 
Tyler Hobbs
DataStax <http://datastax.com/>

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