On 21/01/17 18:46, Stephen Frost wrote:
> * Petr Jelinek (petr.jelinek@2ndquadrant.com) wrote:
>> As we don't know the performance impact is (there was no benchmark done
>> on reasonably current code base) I really don't understand how you can
>> judge if it's worth it or not.
>
> Because I see having checksums as, frankly, something we always should
> have had (as most other databases do, for good reason...) and because
> they will hopefully prevent data loss. I'm willing to give us a fair
> bit to minimize the risk of losing data.
>
>> I stand by the opinion that changing default which affect performance
>> without any benchmark is bad idea.
>
> I'd be surprised if the performance impact has really changed all that
> much since the code went in. Perhaps that's overly optimistic of me.
>
My problem is that we are still only guessing. And while my gut also
tells me that the TPS difference will not be big, it also tells me that
changes like this in important software like PostgreSQL should not be
made based purely on it.
>> And for the record, I care much less about overall TPS, I care a lot
>> more about amount of WAL produced because in 90%+ environments that I
>> work with any increase in WAL amount means at least double the increase
>> in network bandwidth due to replication.
>
> Do you run with all defaults in those environments?
>
For initdb? Mostly yes.
-- Petr Jelinek http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training &
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