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From Paulo Ricardo Motta Gomes <paulo.mo...@chaordicsystems.com>
Subject Re: Efficient bulk range deletions without compactions by dropping SSTables.
Date Thu, 15 May 2014 10:36:52 GMT
Hello Kevin,

In 2.0.X an SSTable is automatically dropped if it contains only
tombstones: https://issues.apache.org/jira/browse/CASSANDRA-5228. However
this will most likely happen if you use LCS. STCS will create sstables of
larger size that will probably have mixed expired and unexpired data.  This
could be solved by the single-sstable tombstone compaction that
unfortunately is not working well (
https://issues.apache.org/jira/browse/CASSANDRA-6563).

I don't know of a way to manually drop specific sstables safely, you could
try implementing a script that compares sstables timestamps to check if an
sstable is safely droppable as done in CASSANDRA-5228. There are proposals
to create a compaction strategy optimized for log only data that only
deletes old sstables but it's not ready yet AFAIK.

Cheers,

Paulo

On Mon, May 12, 2014 at 8:53 PM, Kevin Burton <burton@spinn3r.com> wrote:

> We have a log only data structure… everything is appended and nothing is
> ever updated.
>
> We should be totally fine with having lots of SSTables sitting on disk
> because even if we did a major compaction the data would still look the
> same.
>
> By 'lots' I mean maybe 1000 max.  Maybe 1GB each.
>
> However, I would like a way to delete older data.
>
> One way to solve this could be to just drop an entire SSTable if all the
> records inside have tombstones.
>
> Is this possible, to just drop a specific SSTable?
>
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-- 
*Paulo Motta*

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