Setting Parameters
- All parameter names are case-insensitive. Every parameter takes a
- value of one of five types: Boolean, integer, floating point,
- string or enum. Boolean values can be written as on,
- off, true,
- false, yes,
- no, 1, 0
- (all case-insensitive) or any unambiguous prefix of these.
-
+
+
Parameter Names and Values
- Some settings specify a memory or time value. Each of these has an
- implicit unit, which is either kilobytes, blocks (typically eight
- kilobytes), milliseconds, seconds, or minutes. Default units can be
- found by referencing pg_settings.unit.
- For convenience,
- a different unit can also be specified explicitly. Valid memory units
- are kB (kilobytes), MB
- (megabytes), and GB (gigabytes); valid time units
- are ms (milliseconds), s
- (seconds), min (minutes), h
- (hours), and d (days). Note that the multiplier
- for memory units is 1024, not 1000.
-
+ All parameter names are case-insensitive. Every parameter takes a
+ value of one of five types: Boolean, integer, floating point,
+ string or enum. Boolean values can be written as on,
+ off, true,
+ false, yes,
+ no, 1, 0
+ (all case-insensitive) or any unambiguous prefix of these.
+
- Parameters of type enum are specified in the same way as string
- parameters, but are restricted to a limited set of values. The allowed
- values can be found
- from pg_settings.enumvals.
- Enum parameter values are case-insensitive.
-
+ Some settings specify a memory or time value. Each of these has an
+ implicit unit, which is either kilobytes, blocks (typically eight
+ kilobytes), milliseconds, seconds, or minutes. Default units can be
+ found by referencing pg_settings.unit.
+ For convenience,
+ a different unit can also be specified explicitly. Valid memory units
+ are kB (kilobytes), MB
+ (megabytes), and GB (gigabytes); valid time units
+ are ms (milliseconds), s
+ (seconds), min (minutes), h
+ (hours), and d (days). Note that the multiplier
+ for memory units is 1024, not 1000.
+
- One way to set these parameters is to edit the file
-
postgresql.confpostgresql.conf,- which is normally kept in the data directory. (A default copy is
- installed there when the database cluster directory is
- initialized.) An example of what this file might look like is:
+ Parameters of type enum are specified in the same way as string
+ parameters, but are restricted to a limited set of values. The allowed
+ values can be found
+ from pg_settings.enumvals.
+ Enum parameter values are case-insensitive.
+
+
+
+
+
Setting Parameters via the Configuration File
+
+ One way to set these parameters is to edit the file
+
postgresql.confpostgresql.conf,+ which is normally kept in the data directory. (A default copy is
+ installed there when the database cluster directory is
+ initialized.) An example of what this file might look like is:
# This is a comment
log_connections = yes
search_path = '"$user", public'
shared_buffers = 128MB
- One parameter is specified per line. The equal sign between name and
- value is optional. Whitespace is insignificant and blank lines are
- ignored. Hash marks (#) designate the rest of the
- line as a comment. Parameter values that are not simple identifiers or
- numbers must be single-quoted. To embed a single quote in a parameter
- value, write either two quotes (preferred) or backslash-quote.
-
+ One parameter is specified per line. The equal sign between name and
+ value is optional. Whitespace is insignificant and blank lines are
+ ignored. Hash marks (#) designate the remainder of the
+ line as a comment. Parameter values that are not simple identifiers or
+ numbers must be single-quoted. To embed a single quote in a parameter
+ value, write either two quotes (preferred) or backslash-quote.
+
-
- in configuration file
-
- In addition to parameter settings, the postgresql.conf
- file can contain include directives, which specify
- another file to read and process as if it were inserted into the
- configuration file at this point. Include directives simply look like:
+
+ in configuration file
+
+ In addition to parameter settings, the postgresql.conf
+ file can contain include directives, which specify
+ another file to read and process as if it were inserted into the
+ configuration file at this point. This feature allows a configuration
+ file to be divided into physically separate parts.
+ Include directives simply look like:
include 'filename'
- If the file name is not an absolute path, it is taken as relative to
- the directory containing the referencing configuration file.
- Inclusions can be nested.
-
+ If the file name is not an absolute path, it is taken as relative to
+ the directory containing the referencing configuration file.
+ Inclusions can be nested.
+
-
- in configuration file
-
- Use the same approach as the include directive, continuing
- normally if the file does not exist. A regular include
- will stop with an error if the referenced file is missing, while
- include_if_exists does not. A warning about the missing
- file will be logged.
-
+
+ in configuration file
+
+ There is also an include_if_exists directive, which acts
+ the same as the include directive, except for the behavior
+ when the referenced file does not exist or cannot be read. A regular
+ include will consider this an error condition, but
+ include_if_exists merely logs a message and continues
+ processing the referencing configuration file.
+
-
-
- The configuration file is reread whenever the main server process receives a
- SIGHUP signal (which is most easily sent by means
- of pg_ctl reload). The main server process
- also propagates this signal to all currently running server
- processes so that existing sessions also get the new
- value. Alternatively, you can send the signal to a single server
- process directly. Some parameters can only be set at server start;
- any changes to their entries in the configuration file will be ignored
- until the server is restarted. Invalid parameter settings in the
- configuration file are likewise ignored (but logged) during
- SIGHUP processing.
-
+
+
+ The configuration file is reread whenever the main server process
+ receives a
+ SIGHUP signal (which is most easily sent by means
+ of pg_ctl reload). The main server process
+ also propagates this signal to all currently running server
+ processes so that existing sessions also get the new
+ value. Alternatively, you can send the signal to a single server
+ process directly. Some parameters can only be set at server start;
+ any changes to their entries in the configuration file will be ignored
+ until the server is restarted. Invalid parameter settings in the
+ configuration file are likewise ignored (but logged) during
+ SIGHUP processing.
+
+
- A second way to set these configuration parameters is to give them
- as a command-line option to the postgres command, such as:
+
+
Other Ways to Set Parameters
+
+ A second way to set these configuration parameters is to give them
+ as a command-line option to the postgres command,
+ such as:
postgres -c log_connections=yes -c log_destination='syslog'
- Command-line options override any conflicting settings in
- postgresql.conf. Note that this means you won't
- be able to change the value on-the-fly by editing
- postgresql.conf, so while the command-line
- method might be convenient, it can cost you flexibility later.
-
+ Command-line options override any conflicting settings in
+ postgresql.conf. Note that this means you won't
+ be able to change the value on-the-fly by editing
+ postgresql.conf, so while the command-line
+ method might be convenient, it can cost you flexibility later.
+
- Occasionally it is useful to give a command line option to
- one particular session only. The environment variable
- PGOPTIONS can be used for this purpose on the
- client side:
+ Occasionally it is useful to give a command line option to
+ one particular session only. The environment variable
+ PGOPTIONS can be used for this purpose on the
+ client side:
env PGOPTIONS='-c geqo=off' psql
- (This works for any
libpq-based client application, not- just
psql.) Note that this won't work for
- parameters that are fixed when the server is started or that must be
- specified in postgresql.conf.
-
+
(This works for any
libpq-based client application, not+
just
psql.) Note that this won't work for
+ parameters that are fixed when the server is started or that must be
+ specified in postgresql.conf.
+
- Furthermore, it is possible to assign a set of parameter settings to
- a user or a database. Whenever a session is started, the default
- settings for the user and database involved are loaded. The
- commands
- and ,
- respectively, are used to configure these settings. Per-database
- settings override anything received from the
- postgres command-line or the configuration
- file, and in turn are overridden by per-user settings; both are
- overridden by per-session settings.
-
+ Furthermore, it is possible to assign a set of parameter settings to
+ a user or a database. Whenever a session is started, the default
+ settings for the user and database involved are loaded. The
+ commands
+ and ,
+ respectively, are used to configure these settings. Per-database
+ settings override anything received from the
+ postgres command-line or the configuration
+ file, and in turn are overridden by per-user settings; both are
+ overridden by per-session settings.
+
- Some parameters can be changed in individual
SQL- sessions with the
- command, for example:
+
Some parameters can be changed in individual
SQL+ sessions with the
+ command, for example:
SET ENABLE_SEQSCAN TO OFF;
- If SET is allowed, it overrides all other sources of
- values for the parameter. Some parameters cannot be changed via
- SET: for example, if they control behavior that
- cannot be changed without restarting the entire
-
PostgreSQL server. Also,
- some SET or ALTER parameter modifications
- require superuser permission.
-
+ If SET is allowed, it overrides all other sources of
+ values for the parameter. Some parameters cannot be changed via
+ SET: for example, if they control behavior that
+ cannot be changed without restarting the entire
+
PostgreSQL server. Also, some parameters
+ require superuser permission to change via SET or
+ ALTER.
+
+
- The
- command allows inspection of the current values of all parameters.
-
+
+
Examining Parameter Settings
- The virtual table pg_settings also allows
- displaying and updating session run-time parameters; see
- linkend="view-pg-settings"> for details and a description of the
- different variable types and when they can be changed.
- pg_settings is equivalent to SHOW
- and SET, but can be more convenient
- to use because it can be joined with other tables, or selected from using
- any desired selection condition. It also contains more information about
- what values are allowed for the parameters.
-
+ The
+ command allows inspection of the current values of all parameters.
+
+
+ The virtual table pg_settings also allows
+ displaying and updating session run-time parameters; see
+ linkend="view-pg-settings"> for details and a description of the
+ different variable types and when they can be changed.
+ pg_settings is equivalent to SHOW
+ and SET, but can be more convenient
+ to use because it can be joined with other tables, or selected from using
+ any desired selection condition. It also contains more information about
+ each parameter than is available from SHOW.
+
+
+
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