On 5/13/19 12:33 PM, Julie Nishimura wrote:
We have added new disk volume and about to introduce new tablespace
using this additional disk space. After that, I am going to alter all
user dbs (and template db as well) by runnig the following command:
Not sure why you need to move the template db's they sure not take much
space?
More comments below.
CREATE TABLESPACE vol4
OWNER postgres
LOCATION '/data/vol4';
ALTER DATABASE user_db_1
SET default_tablespace = 'vol4';
...for all dbs..
We have more than 70 different databases (the entire server is about 20
tb). However, for the largest dbs (16tb, 4 tb, and 3 tb), we do not have
valid backups, unfortunately. So, we were debating if we need to run
backups first before introducing all these changes. But we have only 1%
left (about 200 gb).
I have no experience with a setup of this size, someone else will have
to provide real world advice. I would say taking a backup before
preceding is a good idea. Pretty sure time is going to be as much an
issue as space. This would apply to below also. The question is what
options you have to bring cluster or databases down? In particular for
below as:
https://www.postgresql.org/docs/11/sql-alterdatabase.html
"The fourth form changes the default tablespace of the database. Only
the database owner or a superuser can do this; you must also have create
privilege for the new tablespace. This command physically moves any
tables or indexes in the database's old default tablespace to the new
tablespace. The new default tablespace must be empty for this database,
and no one can be connected to the database. Tables and indexes in
non-default tablespaces are unaffected."
What would you suggest? How would you classify the risk of this
operation (creating new tablespace and altering dbs to use it)?
Thanks,
Julie
------------------------------------------------------------------------
*From:* Adrian Klaver <adrian.klaver@xxxxxxxxxxx>
*Sent:* Monday, May 13, 2019 11:19 AM
*To:* Julie Nishimura; pgsql-general@xxxxxxxxxxxxxxxxxxxx; pgsql-general
*Subject:* Re: does postgresql backup require additional space on disk
On 5/13/19 10:59 AM, Julie Nishimura wrote:
Hello,
we are almost out of disk space on one of our servers (99% full). If we
run pg_dump to a diff location, does it require any additional disk
space on our current server? I am asking, because on some other
software, a backup might open transaction which keeps growing and
eventually consume all space, keeping tran open for the backup duration.
Please clarify? Thanks
A pg_dump is a point in time snapshot of the database, so if the cluster
is running then it will advance past the dump snapshot. If the cluster
is not active(close off connections to all but pg_dump) then pg_dump
will be the only transaction.
I think the first thing to ask is what you are trying to achieve?
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
--
Adrian Klaver
adrian.klaver@xxxxxxxxxxx
