Re: Way to quickly detect if database tables/columns/etc. were modified?

On Mon, Oct 31, 2016 at 8:54 AM, John DeSoi <desoi(at)pgedit(dot)com> wrote:

>
> > On Oct 30, 2016, at 4:45 AM, Evan Martin <postgresql2(at)realityexists(dot)net>
> wrote:
> >
> > If I have a query that reads from system tables like pg_class,
> pg_namespace, pg_attribute, pg_type, etc. and I'd like to cache the results
> in my application is there any fast way to detect when any changes have
> been made to these system catalogs? I don't need to know exactly what has
> changed. Some kind of a global "database version" would do, just so I know
> that I need to invalidate my cache (the database definition is rarely
> modified in practice).
>
> Maybe create an event trigger that updates a simple table with the last
> modification time or sends a notification?
>
> https://www.postgresql.org/docs/current/static/sql-createeventtrigger.html
>
> John DeSoi, Ph.D.
>
>
>
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*>Maybe create an event trigger that updates a simple table with the last
modification time or sends a notification?That would certainly work, but
the problem is, that trigger would have to be created for every table in
the database. When you have more than a couple dozen tables, as in
hundreds, it becsmes a huge undertaking.*--
*Melvin Davidson*
I reserve the right to fantasize. Whether or not you
wish to share my fantasy is entirely up to you.