Turn on PostgreSQL logs in Qlik Sense

1. On the Qlik Sense Server, open Postgresql.conf in C:\ProgramData\Qlik\Sense\Repository\PostgreSQL\9.6
2. Add or uncomment the following lines (refer to example of configuration file attached to this article):

logging_collector = on
log_directory = 'pg_log'
log_filename = 'postgresql-%Y-%m-%d_%H%M%S.log'
log_truncate_on_rotation = on
log_rotation_age = 1d    
client_min_messages = notice
log_min_messages = warning
log_min_error_statement = warning
log_line_prefix = '%t'

Average response time:

Slightly higher with logging enabled but the biggest difference was only 4ms. Average time without logging 163ms, with logging 166ms.

Processor time:

PostgreSQL used very little CPU time. Average time without logging was 0.29%, with logging 0.33%.

Memory usage:

Here, slightly less memory was used with logging enabled. Average without logging 1.16GB, with logging 1.13GB.

Log files on disk:

With logging enabled, a number of files were created on the local disk:   About 10MB of data were created every minute.