Re: advice about logging

Thomas Poty wrote:
> This morning, when I arrived to my desk. PostgreSQL had crashed.
>
> I try to inspect the log file but its size about 27G and i cannot check it.

Why?
The interesting entries are probably towards the end of the file.

> So, in order to try to reduce log i wonder which configuration about logging is a good compromise between quantity and quality.
>
> Here is my configuration,:
>
> select name,boot_val,reset_val from pg_settings where name ~ 'log';
> name | boot_val | reset_val
> -----------------------------+--------------------------------+-------------------------
> log_autovacuum_min_duration | -1 | -1
> log_checkpoints | off | off
> log_connections | off | on
> log_destination | stderr | stderr
> log_directory | pg_log | pg_log
> log_disconnections | off | on
> log_duration | off | off
> log_error_verbosity | default | default
> log_executor_stats | off | off
> log_file_mode | 384 | 384
> log_filename | postgresql-%Y-%m-%d_%H%M%S.log | postgresql-%Y-%m-%d.log
> log_hostname | off | off
> log_line_prefix | | %t [%p]: [%l] %u(at)%d
> log_lock_waits | off | off

You want "on". Locks that last more tham a second are a problem.

> log_min_duration_statement | -1 | 1000
> log_min_error_statement | error | error
> log_min_messages | warning | warning

These two are what you want to change.

Set log_min_messages and log_min_error_statement to 'log'.

> log_parser_stats | off | off
> log_planner_stats | off | off
> log_replication_commands | off | off
> log_rotation_age | 1440 | 1440
> log_rotation_size | 10240 | 10240
> log_statement | none | none
> log_statement_stats | off | off
> log_temp_files | -1 | -1

You should set this to some positive value to see if many of your statements
need to write temporary files and increasing work_mem would be a good idea.

> log_timezone | GMT | Europe/Luxembourg
> log_truncate_on_rotation | off | off
> logging_collector | off | on
> syslog_facility | local0 | local0
> syslog_ident | postgres | postgres
> wal_log_hints | off | off
> (31 rows)

Yours,
Laurenz Albe