On 08/11/2018 04:08 PM, Andres Freund wrote:
> Hi,
> On 2018-08-11 15:40:19 +0200, Tomas Vondra wrote:
>> For the record, I can actually reproduce this on 9.6 (haven't tried
>> older releases, but I suspect it's there too). Instead of using the
>> failing subscription, I've used another pgbench script doing this:
>>   SET statement_timeout = 5;
>>   COPY t TO '/dev/null';
>> and doing something like:
>>    pgbench -n -c 20 -T 300 -f copy.sql test
> Just to confirm: That's with the vacuum full and insert running
> concurrently? And then just restarting the above copy.sql (as pgbench
> errors out after the timeouts) until you get the error?

Yes, pretty much.

> I'm a bit confused what the copy + timeout is doing here? It shouldn't
> trigger any invalidations itself, and the backtrace appears to be from
> the insert.sql you posted earlier? Unclear why a copy to /dev/null
> should trigger anything like this?

My goal was to simulate the failing subscription sync, which does COPY
and fails because of duplicate data. The statement_timeout seemed like a
good approximation of that. It may be unnecessary, I don't know.


Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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