On Sat, Sep 30, 2017 at 12:42 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Wed, Sep 27, 2017 at 11:15 PM, Masahiko Sawada <sawada.m...@gmail.com> > wrote: >> I think that making a resolver process have connection caches to each >> foreign server for a while can reduce the overhead of connection to >> foreign servers. These connections will be invalidated by DDLs. Also, >> most of the time we spend to commit a distributed transaction is the >> interaction between the coordinator and foreign servers using >> two-phase commit protocal. So I guess the time in signalling to a >> resolver process would not be a big overhead. > > I agree. Also, in the future, we might try to allow connections to be > shared across backends. I did some research on this a number of years > ago and found that every operating system I investigated had some way > of passing a file descriptor from one process to another -- so a > shared connection cache might be possible.
It sounds good idea. > Also, we might port the whole backend to use threads, and then this > problem goes way. But I don't have time to write that patch this > week. :-) > > It's possible that we might find that neither of the above approaches > are practical and that the performance benefits of resolving the > transaction from the original connection are large enough that we want > to try to make it work anyhow. However, I think we can postpone that > work to a future time. Any general solution to this problem at least > needs to be ABLE to resolve transactions at a later time from a > different session, so let's get that working first, and then see what > else we want to do. > I understood and agreed. I'll post the first version patch of new design to next CF. Regards, -- Masahiko Sawada NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (firstname.lastname@example.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers