Re: Creating a hot copy of PostgreSQL database

Shreesha wrote:
> I was looking for an option of taking the hot copy of the pgsql database periodically or with manual
> trigger. In order to accomplish the same, I need to make sure that all the active transactions are
> halted for some time.
> In MySQL I could do this with FLUSH with READ LOCK. Once the backup is taken, I could UNLOCK the
> tables to continue the normal course of database operations.
> 
> How can I do this in PostgreSQL database?
> 
> 
> Any information on this regard would be highly appreciated.
> 
> 
> Thanks,
> Shreesha.
> 
> P.S.
> I happened to explore Backup and Restore options provided by PostgreSQL.
> a) Taking SQL dump would result in a slower operation and our system wouldn't be able to leverage the
> performance delay caused by this operation.
> b) File system level cache wouldn't be feasible as I don't want my the database server to be shutdown
> for taking the database backup and restore operation.

What do you mean by that? How can you use the cache for creating a copy?

> c) In order to accomplish the archival of WAL logs, I would anyway want to halt the database which
> brings me to the same problem again.

I don't see your point c)
The database server will automatically archive WALs any way you want, and there
is no need to stop or halt the database for that.

To create a copy of a PostgreSQL database cluster, take an online backup and restore it
to some point in time after the end of the backup using the WAL archives.

I am sure that you can automate this if necessary.

Yours,
Laurenz Albe