Re: Discovering time of last database write

On Mon, 2007-01-08 at 03:26, Andy Dale wrote:
> Ok.
>
> The SQL Proxy i am using (HA-JDBC) has some limitations with regard to
> getting it's "cluster" back into sync. If ha-jdbc uses the wrong DB
> (one that has been out of action for a while) as the starting point
> for the cluster it will then try and delete stuff from the other DB's
> on their introduction to the cluster.
>
> I thought the easiest way to control a complete "cluster" restart
> would be to extract the last write date and introduce the one with the
> last write date first, this will make certain the above scenario does
> not happen.

Sorry, I hadn't seen this post when I wrote my lost one.

Yeah, I think having a timestamp column with a rule so it has the
current timestamp when written to and then selecting for the max in each
table would work out. You could probably get fancier, but I'm guessing
that cluster startup is a pretty rare thing, so it's probably easier to
write a script that selects all the tablenames from pg_tables (???) in
your schema and checks for the highest time in each table and selects
the master from that.