On Fri, Feb 5, 2016 at 2:09 PM, Stephen Frost <sfrost@snowman.net> wrote:
* Dave Johansen (davejohansen@gmail.com) wrote: > On Fri, Feb 5, 2016 at 1:54 PM, Stephen Frost <sfrost@snowman.net> wrote: > > * Dave Johansen (davejohansen@gmail.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?
