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ALTER SYSTEM(7)         PostgreSQL 9.5.0 Documentation         ALTER SYSTEM(7)

NAME
       ALTER_SYSTEM - change a server configuration parameter

SYNOPSIS
       ALTER SYSTEM SET configuration_parameter { TO | = } { value | 'value' | DEFAULT }

       ALTER SYSTEM RESET configuration_parameter
       ALTER SYSTEM RESET ALL

DESCRIPTION
       ALTER SYSTEM is used for changing server configuration parameters
       across the entire database cluster. It can be more convenient than the
       traditional method of manually editing the postgresql.conf file.  ALTER
       SYSTEM writes the given parameter setting to the postgresql.auto.conf
       file, which is read in addition to postgresql.conf. Setting a parameter
       to DEFAULT, or using the RESET variant, removes that configuration
       entry from the postgresql.auto.conf file. Use RESET ALL to remove all
       such configuration entries.

       Values set with ALTER SYSTEM will be effective after the next server
       configuration reload (SIGHUP or pg_ctl reload), or after the next
       server restart in the case of parameters that can only be changed at
       server start.

       Only superusers can use ALTER SYSTEM. Also, since this command acts
       directly on the file system and cannot be rolled back, it is not
       allowed inside a transaction block or function.

PARAMETERS
       configuration_parameter
           Name of a settable configuration parameter. Available parameters
           are documented in Chapter 18, Server Configuration, in the
           documentation.

       value
           New value of the parameter. Values can be specified as string
           constants, identifiers, numbers, or comma-separated lists of these,
           as appropriate for the particular parameter.  DEFAULT can be
           written to specify removing the parameter and its value from
           postgresql.auto.conf.

NOTES
       This command can't be used to set data_directory, nor parameters that
       are not allowed in postgresql.conf (e.g., preset options).

       See Section 18.1, "Setting Parameters", in the documentation for other
       ways to set the parameters.

EXAMPLES
       Set the wal_level:

           ALTER SYSTEM SET wal_level = hot_standby;

       Undo that, restoring whatever setting was effective in postgresql.conf:

           ALTER SYSTEM RESET wal_level;

COMPATIBILITY
       The ALTER SYSTEM statement is a PostgreSQL extension.

SEE ALSO
       SET(7), SHOW(7)

PostgreSQL 9.5.0                     2016                      ALTER SYSTEM(7)