Update postgres logging

1) Edit /var/lib/pgsql/data/postgresql.conf

2) Change log_min_duration_statement to 500:

log_min_duration_statement = 500 # -1 is disabled, 0 logs all statements
                                        # and their durations, > 0 logs only
                                        # statements running at least this number
                                        # of milliseconds

This will log any query that runs longer than .5 seconds

3) Reload configurations:

echo "SELECT pg_reload_conf();" |  sudo -u postgres psql 

4) Now in /var/lib/pgsql/data/pg_log you can tail today's logfile, eg:

# tail -f postgresql-Tue.log 
2016-10-25 11:58:06 EDT LOG:  received SIGHUP, reloading configuration files
2016-10-25 11:58:17 EDT LOG:  received SIGHUP, reloading configuration files
2016-10-25 11:58:17 EDT LOG:  parameter "log_min_duration_statement" changed to "500"


and should start to see queries that take more than .5 seconds show up