Re: does wal archiving block the current client connection?

[Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>]

Jeff Frost <jeff(at)frostconsultingllc(dot)com> writes:
> On Tue, 16 May 2006, Simon Riggs wrote:
>> Whatever happened between 02:08 and 02:14 seems important.

> I have the logs and after reviewing /var/log/messages for that time period, 
> there is no other activity besides postgres.

I have a lurking feeling that the still-hypothetical connection between
archiver and foreground operations might come into operation at pg_clog
page boundaries (which require emitting XLOG events) --- that is, every
32K transactions something special happens.  The time delay between
archiver wedging and foreground wedging would then correspond to how
long it took the XID counter to reach the next 32K multiple.  (Jeff,
what transaction rate do you see on that server --- is that a plausible
delay for some thousands of transactions to pass?)

This is just a guess, but if you check the archives for Chris K-L's
out-of-disk-space server meltdown a year or three ago, you'll see
something similar.

			regards, tom lane