NAME

       ALTER_SYSTEM - change a server configuration parameter

SYNOPSIS

       ALTER SYSTEM SET configuration_parameter { TO | = } { 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,
       or after the next server restart in the case of parameters that can only be changed at
       server start. A server configuration reload can be commanded by calling the SQL function
       pg_reload_conf(), running pg_ctl reload, or sending a SIGHUP signal to the main server
       process.

       Only superusers and users granted ALTER SYSTEM privilege on a parameter can change it
       using 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 19.

       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. Values that are neither numbers nor valid identifiers must be quoted.
           DEFAULT can be written to specify removing the parameter and its value from
           postgresql.auto.conf.

           For some list-accepting parameters, quoted values will produce double-quoted output to
           preserve whitespace and commas; for others, double-quotes must be used inside
           single-quoted strings to get this effect.

NOTES

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

       See Section 19.1 for other ways to set the parameters.

       ALTER SYSTEM can be disabled by setting allow_alter_system to off, but this is not a
       security mechanism (as explained in detail in the documentation for this parameter).

EXAMPLES

       Set the wal_level:

           ALTER SYSTEM SET wal_level = replica;

       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)