Re: query performance after database rename

On Wed, Nov 21, 2018 at 6:22 AM Zwettler Markus (OIZ) <
Markus(dot)Zwettler(at)zuerich(dot)ch> wrote:

> Hi,
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>
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> Customer claims about application slowdown after such an database exchange.
>
> I will debug the cluster to get more in-depth in-sight.
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> No connection pooling used.
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>
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> Thanks,
>
> Markus
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> We have to exchange two databases db1 ó db2.
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> alter database [db1|db2] with allow_connections=false;
>
> select pg_terminate_backend (pg_stat_activity.pid) from pg_stat_activity
> where pg_stat_activity.datname in ('db1', 'db2') and pid <>
> pg_backend_pid();
>
> alter database [db1|db2|temp] rename to [temp|db1|db2];
>
> alter database [db1|db2] with allow_connections=true;
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> Version 9.6
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>
Off the top of my head, I'd say after switching to a new database, you'd
have a cold buffer cache. There's a possibility of old statistics. Are you
syncing data changes from the old DB to the new DB?

Also, I'm curious *why* you're doing this.

--
Don Seiler
www.seiler.us