ALTER SYSTEM(7) PostgreSQL 17.4 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 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)
PostgreSQL 17.4 2025 ALTER SYSTEM(7)
postgresql 17.4 - Generated Sat Mar 22 13:25:54 CDT 2025