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From Robert Samuel Newson <rnew...@apache.org>
Subject Re: Corrupt database file
Date Fri, 21 Mar 2014 22:44:02 GMT
"If the DB was corrupted because the disk became full, shouldn't the DB still be fine but just
missing the most recent commits?"

Yes, that’s the virtue of the append-only nature of database files, though the code that
detects file corruption happens when the md5 checksums fail to verify, it’s hard to imagine
it being a false positive.

Did the compaction attempt fail? Can it be replicated? If not, I would reluctantly truncate
a few meg off the file and see if it can be opened (do this when couchdb is not running).
The actual corrupted file would be useful to couchdb developers so that we could investigate
the raw data at the corruption site.

What was the disk system here? RAID? filesystem? Would your disk controllers reorder writers
at all?

B.

On 21 Mar 2014, at 20:19, Tim Tisdall <tisdall@gmail.com> wrote:

> If the DB was corrupted because the disk became full, shouldn't the DB
> still be fine but just missing the most recent commits?  Or would the a
> person need to truncate a certain number of bytes off the end of the DB to
> get it to read properly?
> 
> As for JSON file size... I always dump the DB into a GZ file and then my
> scripts work on it as a GZ'ed file.  In my case the JSON is 20gb and the gz
> file is 3.5gb.  Dealing with the file as a gz adds a little more complexity
> to the script you use to process it, though.
> 
> 
> 
> On 21 March 2014 15:46, Jens Alfke <jens@couchbase.com> wrote:
> 
>> 
>> On Mar 21, 2014, at 8:43 AM, Alexander Shorin <kxepal@gmail.com> wrote:
>> 
>>> we don't have any knowledge about how it was repacked, what
>>> changes it includes, how it different from original CouchDB 1.2.0 and
>>> so on and so forth.
>> 
>> Is that relevant? Nothing's come up in this thread that depends on exact
>> details of CouchDB internals.  Can we focus on the issue at hand, namely
>> that the OP has a CouchDB that ran out of disk space and corrupted its
>> database and he'd like to recover the data?
>> 
>> (IIRC, if there were any source changes from stock 1.2 they were minor,
>> maybe just around branding. Maybe Jan, Dale, or Filipe remember more about
>> it?)
>> 
>>> CouchBase team probably should knows more about their products.
>> 
>> Couchbase's forums are not going to respond to support requests for a
>> product that's been discontinued for over two years, from someone who's
>> (presumably) not a paying customer.
>> 
>> --Jens


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