Re: [Postgres-xc-general] pgxc seems to be running into a deadlock

[Koichi S. <koi...@gm...>]

I looked at the log at datanode and found checkpoint is running too
frequently.   Default checkpoint timeout is 5min.   In your case,
checkpoint runs almost every five seconds (not minutes) in each
datanode.   It is extraordinary.

Could you try to tweak each datanode's postgresql.conf as follows?

1. Longer period for checkpoint_timeout.    Default is 5min.  15min.
will be okay.
2. Larger value for checkpoint_completion_target.   Default is 0.5.
It should be okay.   Larger value, such as 0.7, will make make
checkpoint work more smoothly.
3. Larger value of checkpoint_segment.   Default is 3.  Because your
application updates the database very frequently, this number of
checkpoint segment will be exhausted very easily.   Increase this to,
say, 30 or more.   Each checkpoint_segment (in fact, WAL file)
consumes 16MB of your file space.  I hope this is no problem to you at
all.

I'm afraid too frequent checkpoint causes this kind of error (even
with vanilla PostgreSQL) and this situation is what you should avoid
both in PG and XC.

Would like to know if things are improved.

Best;
---
Koichi Suzuki


2014-02-04 Sandeep Gupta <gup...@gm...>:
> Hi Koichi,
>
>  Just wanted to add that I have send across the datanode and coordinator log
> files in my previous email. My hope is that it may give some insights into
> what could be amiss and any ideas for workaround.
>
>
> Thanks.
> Sandeep
>