Re: BDR, wal segment has been removed, is it possible move forward?

On 6 September 2017 at 01:52, milist ujang <ujang(dot)milist(at)gmail(dot)com> wrote:

> Hi all,
>
> due to space issue and high volume transaction, some wal segments removed
> from pg_xlog on bdr environment.
>

What, you deleted them?

> I had played streams and goldengate (oracle product) , that at capture
> side we can move forward to certain sequence (archivedlog/redolog - wal
> segment in postgres).
>
> So, is it possible to move forward to read recent wal segment in bdr
> environment? (assume data reconciliation will be done manually).
>

BDR can, see bdr.skip_changes_upto .

But PostgreSQL's logical decoding requires a contiguous WAL stream to
maintain a valid catalog_xmin and restart_lsn, so it'll still fail to
advance. So your replication from that node is broken, and you have to part
the node then rejoin. You'll need to manually recover any diverged data.

Don't go in and randomly delete things in the postgres data directory, or
things will break.

The BDR manual warns of the importance of disk space monitoring...

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services