|PostgreSQL Reference Manual - Volume 3 - Server Administration Guide|
by The PostgreSQL Global Development Group
Paperback (6"x9"), 204 pages
RRP £13.95 ($24.95)
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12.2.1 Statistics Collection Configuration
Since collection of statistics adds some overhead to query execution, the system can be configured to collect or not collect information. This is controlled by configuration parameters that are normally set in ‘postgresql.conf’. (See section 4 Server Configuration for details about setting configuration parameters.)
stats_start_collector must be
true for the statistics collector to be launched
at all. This is the default and recommended setting, but it may be
turned off if you have no interest in statistics and want to
squeeze out every last drop of overhead. (The savings is likely to
be small, however.) Note that this option cannot be changed while
the server is running.
stats_row_level control how much information is
actually sent to the collector and thus determine how much run-time
overhead occurs. These respectively determine whether a server
process tracks disk-block-level access
statistics and row-level access statistics and sends these to the collector.
Additionally, per-database transaction commit and abort statistics
are collected if either of these parameters are set.
stats_command_string enables monitoring
of the current command being executed by any server process.
The statistics collector subprocess need not be running to enable this
Normally these parameters are set in ‘postgresql.conf’ so
that they apply to all server processes, but it is possible to turn
them on or off in individual sessions using the
SET command. (To prevent
ordinary users from hiding their activity from the administrator,
only superusers are allowed to change these parameters with
Note: Since the parameters
false, very few statistics are collected in the default configuration. Enabling either of these configuration variables will significantly increase the amount of useful data produced by the statistics facilities, at the expense of additional run-time overhead.
|ISBN 0954612043||PostgreSQL Reference Manual - Volume 3 - Server Administration Guide||See the print edition|