provides a number of support functions which
and other administration and management tools can
use to provide additional functionality, such as remote management
of server log files.
Use of all these functions is only allowed to the superuser by default but may be
allowed to other users by using the
The functions shown in Table F.1 provide write access to files on the machine hosting the server. (See also the functions in Table 9.95 , which provide read-only access.) Only files within the database cluster directory can be accessed, unless the user is a superuser or given one of the pg_read_server_files, or pg_write_server_files roles, as appropriate for the function, but either a relative or absolute path is allowable.
Writes, or appends to, a text file.
Flushes a file or directory to disk.
Renames a file.
Removes a file.
Lists the log files in the
writes the specified
the file named by
false, the file must not already exist. If
the file can already exist, and will be appended to if so.
Returns the number of bytes written.
fsyncs the specified file or directory
. An error is thrown
on failure (e.g., the specified file is not present). Note that
has no effect on this function,
and therefore a PANIC-level error will not be raised even on failure to
flush database files.
renames a file. If
is omitted or NULL, it simply renames
(which must not already exist).
is provided, it first
not already exist), and then renames
. In event of failure of the second rename step,
it will try to rename
before reporting the error.
Returns true on success, false if the source file(s) are not present or
not writable; other cases throw errors.
removes the specified file.
Returns true on success, false if the specified file is not present
call fails; other cases throw errors.
returns the start timestamps and path
names of all the log files in the
parameter must have its
default setting (
) to use this