These parameters control server-wide statistics collection features.
When statistics collection is enabled, the data that is produced can be
accessed via the pg_stat and
pg_statio family of system views.
Refer to Chapter 28 for more information.
track_activities (boolean)
Enables the collection of information on the currently
executing command of each session, along with the time when
that command began execution. This parameter is on by
default. Note that even when enabled, this information is not
visible to all users, only to superusers, roles with privileges of the
pg_read_all_stats role and the user owning the
sessions being reported on (including sessions belonging to a role they
have the privileges of), so it should not represent a security risk.
Only superusers can change this setting.
track_activity_query_size (integer)
Specifies the number of bytes reserved to track the currently
executing command for each active session, for the
pg_stat_activity.query field.
The default value is 1024. This parameter can only be set at server
start.
track_counts (boolean)
Enables collection of statistics on database activity. This parameter is on by default, because the autovacuum daemon needs the collected information. Only superusers can change this setting.
track_io_timing (boolean)
Enables timing of database I/O calls. This parameter is off by
default, because it will repeatedly query the operating system for
the current time, which may cause significant overhead on some
platforms. You can use the pg_test_timing tool to
measure the overhead of timing on your system.
I/O timing information is
displayed in pg_stat_database, in the output of
EXPLAIN when the BUFFERS option is
used, and by pg_stat_statements. Only superusers can
change this setting.
track_functions (enum)
Enables tracking of function call counts and time used. Specify
pl to track only procedural-language functions,
all to also track SQL and C language functions.
The default is none, which disables function
statistics tracking. Only superusers can change this setting.
SQL-language functions that are simple enough to be “inlined” into the calling query will not be tracked, regardless of this setting.
stats_temp_directory (string)
Sets the directory to store temporary statistics data in. This can be
a path relative to the data directory or an absolute path. The default
is pg_stat_tmp. Pointing this at a RAM-based
file system will decrease physical I/O requirements and can lead to
improved performance.
This parameter can only be set in the postgresql.conf
file or on the server command line.
log_statement_stats (boolean)
log_parser_stats (boolean)
log_planner_stats (boolean)
log_executor_stats (boolean)
For each query, output performance statistics of the respective
module to the server log. This is a crude profiling
instrument, similar to the Unix getrusage() operating
system facility. log_statement_stats reports total
statement statistics, while the others report per-module statistics.
log_statement_stats cannot be enabled together with
any of the per-module options. All of these options are disabled by
default. Only superusers can change these settings.