On 2016-01-07 16:48:53 +0530, Amit Kapila wrote: > What I could understand from above e-mail is that Dilip has tried to > extend relation multiple-pages-at-a-time and observed that it gives > comparable or better performance as compare to Andres's idea of > lock-free extension and it doesn't regress the low-thread count case.
I think it's a worthwhile approach to pursue. But until it actually fixes the problem of leaving around uninitialized pages I don't think it's very meaningful to do performance comparisons. > Now, I think here point to discuss is that there could be multiple-ways > for extending a relation multiple-pages-at-a-time like: > > a. Extend the relation page by page and add it to FSM without initializing > it. I think this is what the current patch of Dilip seems to be doing. If > we > want to go via this route, then we need to ensure that whenever we get > the page from FSM, if it is empty and not initialised, then initialise > it. I think that's pretty much unacceptable, for the non-error path at least. One very simple, linux specific, approach would be to simply do fallocate(FALLOC_FL_KEEP_SIZE) to extend the file, that way space is pre-allocated, but not yet marked as allocated. Greetings, Andres Freund -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
