On Fri, Dec 19, 2008 at 1:43 PM, Richard Huxton <d...@archonet.com> wrote: > > Andy Wardley wrote: > > Richard Huxton wrote: > >> Yep - that's what "sharding" is all about - separate disconnected silos > >> of data. > > > > I thought sharding specifically related to horizontal partitioning. i.e. > > splitting one table across several databases, e.g. records with even row > > ids in one DB, odd in another. Apologies if my terminology is wrong. > > > > I was thinking more specifically about vertical partitioning along the > > functional boundaries which wouldn't be sharding by my (possibly incorrect) > > definition. Apologies for being off-topic, too :-) > > If "sharding" means anything at all, then it has to be something other > than partitioning or partial replication, otherwise we could say > "partitioning" or "partial replication". Of course it's entirely > possible it *doesn't* mean anything at all, and is just partitioning2.0
Sharding is horizontal partitioning: splitting your data by a primary key, for example having a few hundred million email boxes spread over thousands of machines keyed by email address. Having your user accounts data in a separate database from say those users' preferences is a form of vertical partitioning. Both in a big system are very likely to be sharded by some kind of internal key. P