Re: Performance lossage in checkpoint dumping

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
>> I am thinking it'd be a good idea if blind write went through fd.c and
>> thus was able to re-use open file descriptors, just like normal writes.
>> This should improve the efficiency of dumping dirty buffers during
>> checkpoint by a noticeable amount.

> Not sure how to handle the beta issue though.

After looking a little more, I think this is too big a change to risk
making for beta. I was thinking it might be an easy change, but it's
not; there's noplace to store the open-relation reference if we don't
have a relcache entry. But we don't want to pay the price of opening a
relcache entry just to dump some buffers.

I recall Vadim speculating about decoupling the storage manager's notion
of open files from the relcache, and having a much more lightweight
open-relation mechanism at the smgr level. That might be a good way
to tackle this. But I'm not going to touch it for 7.1...

regards, tom lane