Hi guys,
I would like to ask you on correct way how to use pqlib for copying data. We tried to do it according documentation but some problems occurred.
We have a multi-threaded application, all threads hold own non-blocking connection into the remote database. Each thread is collecting data and when a buffer is filled they copy data to remote DB as quick as possible. Copying can run several times per minute. The postgresql related part of thread main loop is briefly shown in attached file main.c.
Most of the time copying works well but big delay sometimes occurred. I captured pcap (see
https://ibb.co/2MhmSTZ) and the delay is between getting PGRES_COPY_IN from PQresultStatus function and pushing data. But I am sure that commands PQputCopyData and PQputCopyEnd are called immediately after client gets PQexec.
What am I missing? Is there some other command which we should use?
We are using PostgreSQL 9.6 (PostgreSQL 9.6.10 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-28), 64-bit).
Best regards,
Lukas
