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From Jan Lehnardt <...@apache.org>
Subject Re: format of database sequence
Date Tue, 26 Oct 2010 22:10:54 GMT

On 26 Oct 2010, at 20:59, Adam Kocoloski wrote:

> Hi all, I've been meaning to bring this up for a while.  CouchDB uses integer sequence
numbers in the _changes feed and update_seq values, but I don't see any sensible way to preserve
that interface in BigCouch.  The database sequence in BigCouch needs to combine the sequences
of several database shards; currently it's a string formatted like
> 
> "1234-Base64Data"
> 
> The first piece is the sum of the shard sequence numbers and is not actually used by
BigCouch.  The second piece is the actual data about the state of the cluster.  This format
causes a couple of issues:
> 
> 1) the replicator occasionally sorts sequence numbers and when it does so, it sorts the
BigCouch ones lexicographically and concludes that e.g. "99-..." is the only checkpoint it
will ever need to store.
> 
> 2) client libraries might not treat the sequence as an opaque data type and may break
when operating against a BigCouch.
> 
> My personal preference would be to change the format of the Apache CouchDB sequence to
a string at the next major release. Thoughts?


The next major release is 2.0. +1 on getting that fixed.

Cheers
Jan
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