Re: idea for a geographically distributed database: how best to implement?

Sounds like a mis-guided approach to me...

You might want to consider using latitude and longitude or zip codes or 
taking more of a traditional "GIS" approach rather than duplicating data 
across redundant databases.

Another issue is that you end up having to query every database to find 
proximity... Suppose you have 500 "cells" ? You now have to invoke some sort 
of RPC mechanism on 499 other RDBMS, manage 500 user names and passwords, 
retrieve potentially 500 recordsets, merge the data, etc...

Your problems will continue to get more and more complex... You are better 
off with a single RDBMS and a single schema...




"Andy Ballingall" <andy@areyoulocal.co.uk> wrote in message 
news:ECOWS04Mp8nkfZyufzT00010fe4@smtp-out4.blueyonder.co.uk...
> Hello,
>
> I've got a database for a website which is a variant of the 'show stuff 
> near
> to me' sort of thing.
>
> Rather than host this database on a single server, I have a scheme in mind
> to break the database up geographically so that each one can run 
> comfortably
> on a small server, but I'm not sure about the best way of implementing it.
>
> Here's the scheme:
>
> --------------------------------
> Imagine that the country is split into an array of square cells.
> Each cell contains a database that stores information about people who 
> live
> in the area covered by the cell.
>
> There's one problem with this scheme. What happens if you live near the 
> edge
> of a cell?
>
> My solution is that any inserted data which lies near to the edge of cell 
> A
> is *also* inserted in the database of the relevant neighbouring cell - 
> let's
> say cell B.
>
> Thus, if someone lives in cell B, but close to the border with cell A,
> they'll see the data that is geographically close to
> them, even if it lies in cell A.
>
> --------------------------------
>
> Is this a common pattern?
>
> I could, of course, simply find every insert, update and delete in the
> application and alter the code to explicitly update all the relevant
> databases, but is there a more elegant way of simply saying: "Do this
> transaction on both Database A and Database B" monotonically?
>
> I've had a look at some replication solutions, but they all seem to 
> involve
> replicating an entire database. The advantage of my scheme is that if I 
> can
> distribute my application over large numbers of small servers, I'll end up
> with more bangs for the buck, and it'll be much easier to manage growth by
> managing the number of servers, and number of cells hosted on each server.
>
> Thanks for any suggestions!
> Andy Ballingall
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
>               http://www.postgresql.org/docs/faq
>