Re: General Advice for avoiding concurrency during schema migrations

Hi Ken,

Do you really need to allow web server connections to the database during a
schema migration ? Why not locking them up either with pg_hba.cong or a
firewal rule or symply shut it off temporarily ?

Cheers,
A.A.

On Fri, Mar 21, 2014 at 10:46 AM, Ken Barber <ken(at)bob(dot)sh> wrote:

> Hi there,
>
> I was just wondering if anyone has some general advice for how to
> ensure a schema migration for an application has exclusivity during
> its run.
>
> This is to avoid silly things like, if someone leaves an application
> server running during migration the migration should be able to lock
> somehow to avoid any changes while it is running.
>
> I've taken a look at LOCK TABLE, which can lock a table obviously (and
> I can obviously lock _all_ tables to fake a LOCK DATABASE), but I'm
> wondering if someone has some opinion around just raising the
> transaction isolation level to achieve similar goals?
>
> Any lessons learnt and best practices would be much appreciated :-).
>
> ken.
>
>
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