Re: Expose checkpoint start/finish times into SQL.

[Greg Smith <gsmith(at)gregsmith(dot)com>]

On Fri, 4 Apr 2008, Tom Lane wrote:

> (And you still didn't tell me what the actual failure case was.)

Database stops checkpointing.  WAL files pile up.  In the middle of 
backup, system finally dies, and when it starts recovery there's a bad 
record in the WAL files--which there are now thousands of to apply, and 
the bad one is 4 hours of replay in.  Believe it or not, it goes downhill 
from there.

It's what kicked off the first step that's the big mystery.  The only code 
path I thought of that can block checkpoints like this is when the 
archive_command isn't working anymore, and that wasn't being used.  Given 
some of the other corruption found later and the bad memory issues 
discovered, a bit flipping in the "do I need to checkpoint now?" code or 
data seems just as likely as any other explanation.

--
* Greg Smith gsmith(at)gregsmith(dot)com http://www.gregsmith.com Baltimore, MD