Re: Hourly backup using pg_basebackup

John Scalia <jayknowsunix@gmail.com> writes:

> On 2/6/2015 2:25 PM, Matheus de Oliveira wrote:
>
>     On Fri, Feb 6, 2015 at 4:53 PM, John Scalia <jayknowsunix@gmail.com> wrote:
>
>         We have a python script called by cron on an hourly basis to back up our production database. Currently, the
scriptinvokes pg_dump and takes more than hour to 
>         complete. Hence the script looks to see if it's already running and exits if so. I want to change the script
soit uses pg_basebackup instead since that's so 
>         much faster.
>
>     Have you considered using incremental backup (continuous archiving) instead of a such small backup window?
>
>     See [1]
>
>         My problem is, however, that while I'd like to just have it build a tarball, maybe compressed,  I can't use
a"-X s" option for the wal segments. I think I 
>         understand why I can't use the streaming option with a "-Ft" specified. I'm just concerned about the docs
sayingthat the backup may have problems with fetch as 
>         a wal segment may have expired. Manually testing is showing that the Db needs about 11 minutes to backup with
pg_basebackup,and our wal_keep_segments setting 
>         is 6.  This said, an hour's worth of wal segments should be available, but the six that were there at the
beginningof the backup are not the same six there at 
>         the end. I don't think this is really a problem, but I'd like to get it confirmed. Wouldn't the backup
actuallyhave to take more than hour for this to be an 
>         issue?
>
>     If you use archiving [1], you don't need to worry about saving the segments withing the backup, just let it be
donethrough archive_command. Isn't that an option 
>     for you? If don't, why?
>
> Oh, yes, I did fail to mention that the system where I'm trying this is the primary in a streaming replication
clusterwith (2) hot standby servers. I've mentioned 
> without much traction, that we don't really even need a backup with 3 servers ready to do the work without delays.
LikeI said in the last post, it's all political. 

Er, yes you do.

Suppose someone/thing drops a table erroneously?

Do that and all dozens of your streamers are trash.


>
>     [1] http://www.postgresql.org/docs/current/static/continuous-archiving.html
>
>     Best regards,
>     --
>     Matheus de Oliveira
>     Analista de Banco de Dados
>     Dextra Sistemas - MPS.Br nível F!
>     www.dextra.com.br/postgres
>

--
Jerry Sievers
Postgres DBA/Development Consulting
e: postgres.consulting@comcast.net
p: 312.241.7800