AW: query performance after database rename

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От Zwettler Markus (OIZ)
Тема AW: query performance after database rename
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Msg-id 2517bbd286ed41388e4a474314682e76@zuerich.ch
обсуждение исходный текст
Ответ на Re: query performance after database rename  (Don Seiler <don@seiler.us>)
Список pgsql-admin

Hi,

 

Don't ask me why. L

 

Both databases have the same structure.

Both databases are in use before and after the switch.

Buffer cache should be warm, statistics should be up-to-date, therefore.

 

Thanks,

Markus

 

 

 

Von: Don Seiler <don@seiler.us>
Gesendet: Mittwoch, 21. November 2018 15:54
An: Zwettler Markus (OIZ) <Markus.Zwettler@zuerich.ch>
Cc: srinivasoguri7@gmail.com; pgsql-admin@lists.postgresql.org
Betreff: Re: query performance after database rename

 

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

Hi,

 

Customer claims about application slowdown after such an database exchange.

I will debug the cluster to get more in-depth in-sight.

No connection pooling used.

 

Thanks,

Markus

 

 

We have to exchange two databases db1 ó db2.

 

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;

 

Version 9.6

 

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

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