On Wed, Dec 7, 2016 at 4:05 PM, Michael Paquier <michael.paqu...@gmail.com> wrote: > On Wed, Dec 7, 2016 at 2:49 PM, Kyotaro HORIGUCHI > <horiguchi.kyot...@lab.ntt.co.jp> wrote: >> Aside from measurement of the two sorting methods, I'd like to >> point out that quorum commit basically doesn't need >> sorting. Counting conforming santdbys while scanning the >> walsender(receiver) LSN list comparing with the target LSN is >> O(n). Small refactoring of SyncRerpGetOldestSyncRecPtr would >> enough to do that.
What does the target LSN mean here? > Indeed, I haven't thought about that, and that's a no-brainer. That > would remove the need to allocate and sort each array, what is simply > needed is to track the number of times a newest value has been found. > So what this processing would do is updating the write/flush/apply > values for the first k loops if the new value is *older* than the > current one, where k is the quorum number, and between k+1 and N the > value gets updated only if the value compared is newer. No need to > take the mutex lock for a long time as well. Sorry, I could not understand this algorithm. Could you elaborate this? It takes only O(n) times? > By the way, the patch now > conflicts on HEAD, it needs a refresh. Thanks, I'll post the latest patch. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers