ALTER_SYSTEM(7) - phpMan

ALTER SYSTEM(7) PostgreSQL 12.18 Documentation ALTER SYSTEM(7)

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 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 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, nor parameters that are not allowed in
postgresql.conf (e.g., preset options).

See Section 19.1 for other ways to set the parameters.

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.