Re: pg_restore with connection limit 0

On 11/27/19 7:06 AM, Олег Самойлов wrote:
> Hi all.
> 
> I have task to refresh a test database from a production database (with masking) on the fly. To make masking we use pg_restore --create with three stages restoration. And one of the problem is daemons writing concurrently in the time of the restoration of a database. I need to block them in time of the restoration. ALLOW_CONNECTIONS=true don't work in this case, because it blocks a superuser too. We use CONNECTION LIMIT 0, because this blocks almost all, except a superuser. But to prevent a race condition we must set this in the same query as CREATE DATABASE, the postgresql syntax allow this. Now this is rather complex procedure:
> 
> We get `pg_restore --create --list −−section=pre−data` and `pg_restore ---stage --list −−section=pre−data`, diff them to get difference.
> Get `pg_restore --create --use-list=diff −−section=pre−data` to get sql.
> Edit sql: remove ALTER DATABASE ... CONNECTION LIMIT ... if exist, add CONNECTION LIMIT 0 to the CREATE DATABASE.
> Send sql to the postgresql.
> And so on.
> 
> Will be convenient to add CONNECTION LIMIT 0 to the CREATE DATABASE just by option of pg_restore.
> And will be even more straight approach do not use CONNECTION LIMIT 0 is this case, but change ALLOW_CONNECTIONS to accept values: false, true, superuser. ("Superuser" to accept connections from superuser only).
> 
> 

Why not use pg_hba.conf to allow only connection from superuser for 
duration?



-- 
Adrian Klaver
adrian.klaver@aklaver.com