On Fri, May 19, 2017 at 7:55 AM, Rafia Sabih <rafia.sa...@enterprisedb.com> wrote: > While analysing the performance of TPC-H queries for the newly developed > parallel-operators, viz, parallel index, bitmap heap scan, etc. we noticed > that the time taken by gather node is significant. On investigation, as per > the current method it copies each tuple to the shared queue and notifies the > receiver. Since, this copying is done in shared queue, a lot of locking and > latching overhead is there. > > So, in this POC patch I tried to copy all the tuples in a local queue thus > avoiding all the locks and latches. Once, the local queue is filled as per > it's capacity, tuples are transferred to the shared queue. Once, all the > tuples are transferred the receiver is sent the notification about the same.
What if, instead of doing this, we switched the shm_mq stuff to use atomics? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers