Re: Assertion failure in walreceiver

Greg Stark wrote:
> I tried to set up a simple master/slave setup and immediately ran into
> this assertion failure. The slave is just a cold copy of the database
> immediately after initdb. The first WAL segment hasn't been archived
> yet. It sees that the first archive fail hasn't been archived yet,
> starts up walreceiver but it looks like the start point hasn't been
> initialized yet because it hasn't processed any checkpoint WAL records
> yet.
>
> $ /usr/local/pgsql/bin/postgres -D /var/tmp/pg85/s/
> LOG: database system was shut down at 2010-02-23 14:30:08 GMT
> cp: cannot stat `/var/tmp/pg85/w/000000010000000000000000': No such
> file or directory
> TRAP: FailedAssertion("!(startpoint.xlogid != 0 || startpoint.xrecoff
> != 0)", File: "libpqwalreceiver.c", Line: 87)
> LOG: WAL receiver process (PID 3536) was terminated by signal 6: Aborted
> LOG: terminating any other active server processes
> LOG: startup process (PID 3534) exited with exit code 2
> LOG: aborting startup due to startup process failure

Hmm, interesting corner case. That assertion is checking that the
streaming starting point is initialized correctly, but 0/0 is actually a
valid value when you start streaming from the very first WAL segment.

I guess we can just remove the assertion. If an incorrect zero value
finds its way there due to some bug, nothing particularly bad will
happen; you'll just get an error because the WAL segment most likely
doesn't exist in the primary anymore.

--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com