Amit Kapila <amit.kapila16@gmail.com> writes:
> > I am not sure about rsync, in my production server I have for example
> > 111 GB in pg_xlog and if I run rsync for pg_xlog it must send ~ 40GB
> > of new WALs I think.
> >
>
> Isn't the difference between old and new is just the last WAL segment
> file? What is the source of this difference?
Postgres generate WAL files forward, and at standby too :-(
For example:
=== master ===
$ psql -c 'select pg_current_xlog_insert_location()'pg_current_xlog_insert_location
---------------------------------4ED09/34A74590
(1 row)
$ ls 9.2/main/pg_xlog/ | awk '/4ED0900000034/,/xxx/ { print }' | wc -l
2262
==============
=== standby ===
$ psql -c 'select pg_last_xlog_replay_location()'pg_last_xlog_replay_location
------------------------------4ED0A/AECFD7B8
(1 row)
postgres@avi-sql29:~$ ls 9.2/main/pg_xlog/ | awk '/4ED0A000000AE/,/xxx/ { print }' | wc -l
2456
===============
See https://www.postgresql.org/docs/9.2/static/wal-configuration.html
> they are recycled (renamed to become the next segments in the numbered sequence)
--
Sergey Burladyan