Re: WAL consistency check facility

On Fri, Nov 4, 2016 at 4:16 AM, Kuntal Ghosh  wrote:
> On Thu, Nov 3, 2016 at 8:24 PM, Robert Haas  wrote:
>> On Wed, Nov 2, 2016 at 10:30 AM, Kuntal Ghosh
>>  wrote:
>>> - Another suggestion was to remove wal_consistency from PostgresNode.pm
>>> because small buildfarm machines may suffer on it. Although I've no
>>> experience in this matter, I would like to be certain that nothings breaks
>>> in recovery tests after some modifications.
>>
>> I think running the whole test suite with this enabled is going to
>> provoke complaints from buildfarm owners.  That's too bad, because I
>> agree with you that it would be nice to have the test coverage, but it
>> seems that many of the buildfarm machines are VMs with very minimal
>> resource allocations -- or very old physical machines -- or running
>> with settings like CLOBBER_CACHE_ALWAYS that make runs very slow.  If
>> you blow on them too hard, they fall over.

Count me in. My RPIs won't like that! Actually I have a couple of
things internally mimicking the buildfarm client code on machines with
far higher capacity. And FWIW I am definitely going to enable this
option in the test suite, finishing with reports here.

> Thanks Robert. I got your point. Then, as Michael has suggested, it is nice to
> have some environment variable to pass optional conf parameters during
> tap-tests.
> Implementing this feature actually solves the problem.

We just need make PostgresNode.pm aware of something like PGTAPOPTIONS
to enforce a server started by TAP tests to append options to it.
There is already PGCTLTIMEOUT that behaves similarly. Even if this
brings extra load to buildfarm owners, that will limit complaints.
-- 
Michael