Re: Setting up streaming replication with new server as master?

On Fri, Feb 5, 2016 at 2:09 PM, Stephen Frost <sfrost(at)snowman(dot)net> wrote:

> * Dave Johansen (davejohansen(at)gmail(dot)com) wrote:
> > On Fri, Feb 5, 2016 at 1:54 PM, Stephen Frost <sfrost(at)snowman(dot)net>
> wrote:
> > > * Dave Johansen (davejohansen(at)gmail(dot)com) wrote:
> > > > So will pg_basebackup keep copying the new data that is added over
> the
> > > > weekend until I tell it to stop? If so, then on Monday, can I close
> > > things
> > > > down, wait for the WAL to finish, swap the roles of the 2 server and
> then
> > > > restart?
> > >
> > > No, pg_basebackup will take a snapshot of the current system,
> > > essentially. You can set up the new system to connect to the current
> > > system, using recovery.conf, to pull the WAL records and apply them to
> > > the new server.
> > >
> >
> > So do I set that up before running pg_basebackup?
> >
> > Or in other words, pg_basebackup will get all of the existing data and
> then
> > the setup using recovery.conf will get the new data?
>
> Right. Note that to use pg_basebackup or to have a replica connect to
> the existing system, you need to have archive_mode set to archive or
> higher (and you should at least do hot_standby, really), and have
> max_wal_senders set higher than 0 (I tend to set it to about 3, just
> because it uses little in the way of resources, etc). If you have a
> high transaction rate, you might also want to set wal_keep_segments up a
> bit.
>

Just to clarify, do you mean *wal_level* set to archive or higher (i.e.
wal_level instead of archive_mode)?

One final question, step #5 in "How to Use" (
https://wiki.postgresql.org/wiki/Streaming_Replication#How_to_Use ) makes
it sounds like having wal_keep_segments at a high enough level means that
archive_mode being on isn't necessary. Is that a correct understanding of
the description there?

Thanks a ton for all the help!
Dave