Hi, On 2023-03-05 05:42:06 +0300, Трофимов Иван wrote: > I was running some benchmarks for PG driver built on top of libpq async > functionality, > and noticed that recv syscalls issued by the application are limited by 16Kb, > which seems to > be inBufSize coming from makeEmptyPGconn in interfaces/libpq/fe-connect.c. > > Hacking that to higher values allowed my benchmarks to issue drastically less > syscalls > when running some heavy selects, both in local and cloud environments, which > made them > significantly faster. > > I believe there is a reason for that value to be 16Kb, but i was wondering if > it's safe to change > this default to user-provided value, and if it is - could this functionality > be > added into API?
I've observed the small buffer size hurting as well - not just client side, also on the serve. But I don't think we necessarily need to make it configurable. From what I can tell the pain mainly comes using the read/send buffers when they don't even help, because the message data we're processing is bigger than the buffer size. When we need to receive / send data that we know is bigger than the the buffer, we should copy the portion that is still in the buffer, and then send/receive directly from the data to be sent/received. Greetings, Andres Freund