> > I'm going to propose libpq debug log for analysis of queries on the > > application > side. > > I think that it is useful to determine whether the cause is on the > > application > side or the server side when a slow query occurs. > > Do you mean you want to monitor the protocol message exchange at the client > side to analyze performance issues, right? Actually, this might be useful to > determin where is the problem, for example, the client application, the > backend > PostgreSQL, or somewhere in the network. > > Such logging can be implemented in the application, but if libpq provides the > standard way, it would be helpful to resolve a problem without modifying the > application code.
Since I'd like to monitor the information the server and the client exchange, I think monitoring protocol messages is good. When a slow query is occurs, we check this client side trace log. The purpose of this log acquisition I thought is to identify where is the problem: server side, application side or traffic. And if the problem is in application side, checking the trace log to identify what is the problem. > > The provided information is "date and time" at which execution of processing > is started, "query", "application side processing", which is picked up > information from PQtrace(), and "connection id", which is for uniquely > identifying the connection. > > I couldn't image how this is like. Could you show us a sample of log lines in > your head? I am roughly thinking as follows; ... START : 2018/09/03 18:16:35.357 CONNECTION(1) STATUS : Connection SEND MESSAGE : 2018/09/03 18:16:35.358 <information send to backend...> RECEIVE MESSAGE : 2018/09/03 18:16:35.359 <information receive from backend...> END : 2018/09/03 18:16:35.360 ... START : 2018/09/03 18:16:35.357 CONNECTION(1) QUERY : DECLARE myportal CURSOR FOR select * from pg_database SEND MESSAGE : 2018/09/03 18:16:35.358 <information send to backend...> RECEIVE MESSAGE : 2018/09/03 18:16:35.359 <information receive from backend...> END : 2018/09/03 18:16:35.360 ... > > To collect the log, set the connection string or environment variable. > > - logdir or PGLOGDIR : directory where log file written > > - logsize or PGLOGSIZE : maximum log size > > How we can specify the log file name? What should happen if a file size > exceeds > to PGLOGSIZE? The log file name is determined as follow. libpq-%ApplicationName-%Y-%m-%d_%H%M%S.log When the log file size exceeds to PGLOGSIZE, the log is output to another file. Regards, Aya Iwata
