$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.279 2005/08/12 18:23:53 tgl Exp $

linkend="functions-admin-signal-table"> send control signals to

other server processes. Use of these functions is restricted

<title>Server Signalling Functions</title>

<literal><function>pg_cancel_backend</function>(<parameter>pid</parameter> <type>int</>)</literal>

<entry>Cause server processes to reload their configuration files</entry>

postmaster, causing reload of the configuration files

in all server processes.

<literal><function>pg_start_backup</function>(<parameter>label</> <type>text</>)</literal>

<entry><function>pg_column_size</function>(<type>any</type>)</entry>

<literal><function>pg_tablespace_size</function>(<type>oid</type>)</literal>

<literal><function>pg_tablespace_size</function>(<type>name</type>)</literal>

<literal><function>pg_database_size</function>(<type>oid</type>)</literal>

<literal><function>pg_database_size</function>(<type>name</type>)</literal>

<literal><function>pg_relation_size</function>(<type>oid</type>)</literal>

<literal><function>pg_relation_size</function>(<type>text</type>)</literal>

<literal><function>pg_complete_relation_size</function>(<type>oid</type>)</literal>

<literal><function>pg_complete_relation_size</function>(<type>text</type>)</literal>

<literal><function>pg_size_pretty</function>(<type>bigint</type>)</literal>

files on the machine hosting the server. Only files within the

database cluster directory and the <varname>log_directory</> may be

accessed. Use a relative path for files within the cluster directory,

and a path matching the <varname>log_directory</> configuration setting

for log files. Use of these functions is restricted to superusers.

<literal><function>pg_file_length</function>(<parameter>filename</> <type>text</>)</literal>

<entry>Return the file length</entry>

<literal><function>pg_ls_dir</function>(<parameter>dirname</> <type>text</>)</literal>

<literal><function>pg_read_file</function>(<parameter>filename</> <type>text</>, <parameter>offset</> <type>int8</>, <parameter>length</> <type>int8</>)</literal>

<entry>Return the contents of a text file</entry>

<literal><function>pg_stat_file</function>(<parameter>filename</> <type>text</>)</literal>

<entry>Return information about the file</entry>

at the given offset, returning at most length bytes (less if the

end of file is reached first). If offset is negative,

it is relative to the end of the file.

Use it like this:

<programlisting>

SELECT *

FROM pg_stat_file('filename')

AS s(length int8, atime timestamptz, mtime timestamptz,

ctime timestamptz, isdir bool);

</programlisting>

logfile to be rotated. This works only when <varname>redirect_stderr</>

is used for logging. Use of this function is restricted

<title>Server Logfile Functions</title>

<entry>Rotate server's logfile</entry>

if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER) &&

PgArchPID != 0 && Shutdown == NoShutdown)

/*

kill(PgArchPID, SIGUSR1);

if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE) &&

SysLoggerPID != 0)

{

/* Tell syslogger to rotate logfile */

}