Обсуждение: PITR compatible backup with exclusion

Martin Bruset Solberg schrieb am 26.01.2015 um 13:17:
> I am faced with a scenario of backing up a database with one large
> (partitioned) table, and several smaller tables. The large table is
> so big that backing it up is proving problematic both in terms of
> storage and time spent backing up and restoring. The backup of the
> table itself is also reduntant, as the table data can be recreated by
> importing from the source files. This data is not mission critical
> for the application, so a speedy recovery is not urgent. The data
> from the smaller tables, however, is critical. The combined size of
> the rest of the database is not a problem neither in terms of storage
> or backup/restore speed, so a logical backup excluding the large
> table/schema works fine. But logical backup is not sufficiant, as I
> need to be able to do PITR in case of disaster.
>
> So my question is, what are my options when I want to make a PITR
> compatible backup, and need to exclude a table/schema/tablespace of
> the database? Any suggestions welcome...


What if you change that big table to UNLOGGED?
As unlogged tables don't generate WAL they don't contribute to the PITR "restore time"
(and they won't be restored if you have to do a PITR!)

It will be included in the necessary base backup though if I'm not mistaken.

Thomas

El mar, 27-01-2015 a las 08:36 +0100, Thomas Kellerer escribió:
> Martin Bruset Solberg schrieb am 26.01.2015 um 13:17:
> > I am faced with a scenario of backing up a database with one large
> > (partitioned) table, and several smaller tables. The large table is
> > so big that backing it up is proving problematic both in terms of
> > storage and time spent backing up and restoring. The backup of the
> > table itself is also reduntant, as the table data can be recreated by
> > importing from the source files. This data is not mission critical
> > for the application, so a speedy recovery is not urgent. The data
> > from the smaller tables, however, is critical. The combined size of
> > the rest of the database is not a problem neither in terms of storage
> > or backup/restore speed, so a logical backup excluding the large
> > table/schema works fine. But logical backup is not sufficiant, as I
> > need to be able to do PITR in case of disaster.
> >
> > So my question is, what are my options when I want to make a PITR
> > compatible backup, and need to exclude a table/schema/tablespace of
> > the database? Any suggestions welcome...
>
>
> What if you change that big table to UNLOGGED?
> As unlogged tables don't generate WAL they don't contribute to the PITR "restore time"
> (and they won't be restored if you have to do a PITR!)

However, they are not crash-safe: an unlogged table is automatically
truncated after a crash or unclean shutdown.
>
> It will be included in the necessary base backup though if I'm not mistaken.
>
> Thomas
>
>
>

jaime soler wrote on 14.03.2015 12:30:
>> What if you change that big table to UNLOGGED?
>> As unlogged tables don't generate WAL they don't contribute to the PITR "restore time"
>> (and they won't be restored if you have to do a PITR!)
>
> However, they are not crash-safe: an unlogged table is automatically
> truncated after a crash or unclean shutdown.

That is correct, but Martin wrote in the initial question:

> The backup of the table itself is also reduntant,
>as the table data can be recreated by importing from the source files

So if the data lost, it apparently doesn't matter.