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From Dave Cottlehuber <...@jsonified.com>
Subject Re: Setting compaction folder
Date Wed, 25 Sep 2013 09:13:40 GMT

On 24. September 2013 at 15:36:41, Boaz Citrin (bcitrin@gmail.com) wrote:
>
>Yep, I know that...
>Had this at strict windows with fragmentation 70% so either this wasn't so
>fragmented (but did fill HD...) or the window of 4 hours wasn't big enough.
>
>
>On Tue, Sep 24, 2013 at 4:33 PM, Stanley Iriele wrote:
>
>> Random question... Did you know you can specify parameters for couchdb to
>> run automatic compaction?
>> On Sep 24, 2013 9:30 AM, "Boaz Citrin" wrote:
>>
>> > Hello,
>> >
>> > HD is full. Need to compact db and views, but no space for temporary
>> > compaction file.
>> > I have another drive whose size is enough for this temporary file but not
>> > for the whole db.
>> >
>> > Is it possible to tell couchdb where to store the temporary db file
>> during
>> > compaction?
>> >
>> > Thanks!

Not really. There are good reasons for this unfortunately; the original & new db need
to be present in the same filesystem so couch can swap over really fast when complete.

There are 2 choices:

with downtime: delete the view file completely (as this is what compaction will eventually
do anyway), compact the db, regenerate the views.

without much** downtime: set up a 2nd couchdb instance that uses a different port, and the
other partition. set up one-shot replication from couch1/db -> couch2/db. trigger view
generation for each ddoc. Swap couch instances over and use the replication again to ensure
couch2/db is up to date with the very latest changes from couch1/db.

There are a few more advanced variations on this, such as clone your entire /db/ dir to the
2nd drive, use rsync to get it up to date, and then swap couch instances very quickly, &
using a fancy reverse proxy config in front to flip from old -> new.

If you have more info about your h/w, OS, couch size & access patterns, maybe we can find
a more tailored approach that still saves your bacon.

A+
Dave



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