Re: does postgresql backup require additional space on disk - Mailing list pgsql-general

From Julie Nishimura
Subject Re: does postgresql backup require additional space on disk
Date
Msg-id BYAPR08MB5014D98A67FBD6F9A3F92AEEAC0F0@BYAPR08MB5014.namprd08.prod.outlook.com
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In response to Re: does postgresql backup require additional space on disk  (Adrian Klaver <adrian.klaver@aklaver.com>)
Responses Re: does postgresql backup require additional space on disk
List pgsql-general
Adrian, thanks for your reply. I previously found this link, which mentioned 8.2, that is why I assumed it will work with 8.3.

Too bad we don't have dev with the same version. I guess I will create new tablespace using new vol, move the smallest db for which I have backup, create new test table and examine new/existing tables if they have moved by selecting tablespace from pg_tables... right?

 





From: Adrian Klaver <adrian.klaver@aklaver.com>
Sent: Monday, May 13, 2019 2:47 PM
To: Julie Nishimura; pgsql-general@lists.postgresql.org; pgsql-general
Subject: Re: does postgresql backup require additional space on disk
 
On 5/13/19 1:26 PM, Julie Nishimura wrote:
> Adrian, thanks for your reply. Couple of clarifications/questions:
> 1) we are on 8.3 for this server

8.3 does not have ALTER DATABASE name SET TABLESPACE :

https://www.postgresql.org/docs/8.3/sql-alterdatabase.html

It does appear until 8.4.


> 2) I was under impression, that "ALTER DATABASE name SET TABLESPACE
> new_tablespace" won't move anything, and just utilize the new_tablespace
> for new tables/indexes. If we would want to move existing tables, we
> would need to move them one by one by

No think of ALTER DATABASE name SET TABLESPACE  as a bulk operation of
ALTER TABLE /mytableschema.mytable/ SET TABLESPACE /mynewtablespace/
across all existing tables.  This assumes the all existing tables live
in the  current default tablespace. It is moot in your case as 8.3 is
not capable of doing this.

> ALTER TABLE /mytableschema.mytable/ SET TABLESPACE /mynewtablespace/
> /
> /

The above is your option in 8.3.

> 3) I thought if I want to have any newly created dbs go to the new vol,
> I need to alter template.

It is not required you can spec the tablespace in the CREATE DATABASE
command:

https://www.postgresql.org/docs/8.3/sql-createdatabase.html

Though you can move them to make the tablespace the default. See above link.


> 4) I was also thinking about changing parameters in config file to point
> to the newly volume and reload postgresql.conf
>
> default_tablespace
>
> temp_tablespaces

You could that. If you do it, moving the template tables would be redundant.

>
>
> Am I wrong here?
>
>
> Thanks,
>
> Julie
>
>


--
Adrian Klaver
adrian.klaver@aklaver.com

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