launchpad-dev team mailing list archive

[Martin Pool <mbp@xxxxxxxxxxxxx>]

On 16 November 2010 15:37, Robert Collins <robertc@xxxxxxxxxxxxxxxxx> wrote:
> Gary and I are attending a course on Cassandra, which several teams in
> Canonical are evaluating for use.

Thanks for the update.

> Counting - assigning numbers based on data in the database - is
> tricky, and there are a few techniques to do it. Running a counting
> service - a single point of failure that manages a lock and can issue
> numbers - is something we'd probably need to do to allocate bugids,
> were we to migrate to Cassandra.

I'm curious just what this means:

* you can't get an acid view across the database therefore you can't
say "there are 700,000 bugs so I'm making 700,001"?
* even just getting an approximate count is expensive?

I guess bug ids are user visible as being medium-size consecutive
integers, but presumably for any new objects one would want to use
uuid-like identifiers.

-- 
Martin