On 4.9.2014 01:34, Tomas Vondra wrote: > On 20.8.2014 20:32, Robert Haas wrote: >> >> As I see it, the advantage of Jeff's approach is that it doesn't >> really matter whether our estimates are accurate or not. We don't >> have to decide at the beginning how many batches to do, and then >> possibly end up using too much or too little memory per batch if we're >> wrong; we can let the amount of memory actually used during execution >> determine the number of batches. That seems good. Of course, a hash
Also, you don't actually have to decide the number of batches at the very beginning. You can start start with nbatch=1 and decide how many batches to use when the work_mem is reached. I.e. at exactly the same moment / using the same amount of info as with Jeff's approach. No? Tomas -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
