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$PostgreSQL: pgsql/doc/src/sgml/func.sgml,v 1.278 2005/08/1215:57:48 momjian Exp $

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PostgreSQL documentation

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<para>

The functions shown in <xref

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

other server processes. Use ofthis function is restricted

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

other server processes. Use ofthese functions is restricted

to superusers.

</para>

<table id="functions-admin-signal-table">

<title>Backend Signalling Functions</title>

<title>Server Signalling Functions</title>

<tgroup cols="3">

<thead>

<row><entry>Name</entry> <entry>Return Type</entry> <entry>Description</entry>

<tbody>

<row>

<entry>

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

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

</entry>

<entry><type>int</type></entry>

<entry>Cancel a backend's current query</entry>

<literal><function>pg_reload_conf</function>()</literal>

</entry>

<entry><type>int</type></entry>

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

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

</row>

</tbody>

</tgroup>

</para>

<para>

<function>pg_reload_conf</> sends a SIGHUP signal to the

postmaster, causingthereload of the configuration files

in allbackend processes.

postmaster, causing reload of the configuration files

in allserver processes.

</para>

<indexterm zone="functions-admin">

<tbody>

<row>

<entry>

<literal><function>pg_start_backup</function>(<parameter>label_text</parameter>)</literal>

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

</entry>

<entry><type>text</type></entry>

<entry>Set up for performing on-line backup</entry>

<tbody>

<row>

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

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

<entry><type>integer</type></entry>

<entry>Number of bytes used to store a particular value (possibly compressed)</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Total disk space used by the tablespace with the specified OID</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Total disk space used by the tablespace with the specified name</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Total disk space used by the database with the specified OID</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Total disk space used by the database with the specified name</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Disk space used by the table or index with the specified OID</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Disk space used by the table or index with the specified name.

The name may be qualified with a schema name</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Total disk space used by the table with the specified OID,

including indexes and toasted data</entry>

</row>

<row>

<entry>

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

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

</entry>

<entry><type>bigint</type></entry>

<entry>Total disk space used by the table with the specified name,

</row>

<row>

<entry>

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

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

</entry>

<entry><type>text</type></entry>

<entry>Converts a size in bytes into a human-readable format with size units</entry>

<para>

The functions shown in <xref

linkend="functions-admin-genfile"> provide native file access to

files on the machine hosting the server. Only filesrelative to

the cluster directoryare allowed,and the <varname>log_directory</>,

because the log file directory might be stored outside the

superusers.

files on the machine hosting the server. Only fileswithin the

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

accessed. Use a relative path for files within thecluster directory,

for log files. Use of these functions is restricted tosuperusers.

</para>

<table id="functions-admin-genfile">

<tbody>

<row>

<entry>

<literal><function>pg_file_length</function>(<parameter>filename_text</parameter>)</literal>

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

<indexterm zone="functions-admin">

<primary>pg_file_length</primary>

</indexterm>

</entry>

<entry><type>int8</type></entry>

<entry>Returns the file length</entry>

<entry>Return the file length</entry>

</row>

<row>

<entry>

<literal><function>pg_ls_dir</function>(<parameter>dirname_text</parameter>,<parameter>fullpath_bool</parameter>)</literal>

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

<indexterm zone="functions-admin">

<primary>pg_ls_dir</primary>

</indexterm>

</row>

<row>

<entry>

<literal><function>pg_read_file</function>(<parameter>filename_text</parameter>,

<parameter>offset_int8</parameter>,<parameter>length_int8</parameter>)</literal>

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

</entry>

<entry><type>text</type></entry>

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

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

</row>

<row>

<entry>

<literal><function>pg_stat_file</function>(<parameter>filename_text</parameter>)</literal>

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

</entry>

<entry><type>record</type></entry>

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

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

</row>

</tbody>

</tgroup>

</indexterm>

<para>

<function>pg_read_file()</> returns part of a textfile, starting

at the given offset, returning length bytes. If offset is negative,

it is treated relative to the end of the file.

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.

</para>

<indexterm zone="functions-admin">

<function>pg_stat_file()</> returns a record containing the

length, last accessed timestamp, last modified timestamp,

creation timestamp, and a flag indicating if it is a directory.

Use it like this:

<programlisting>

SELECT *

FROM pg_stat_file('filename')

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

ctime timestamptz, isdir bool);

</programlisting>

</para>

<para>

The function shown in <xref

linkend="functions-admin-logfile"> forces the server

logfile to be rotated if <varname>redirect_stderr</>

is used for logging. Use of thisfunctions is restricted

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

is used for logging. Use of thisfunction is restricted

to superusers.

</para>

<table id="functions-admin-logfile">

<title>Backend Logfile Functions</title>

<title>Server Logfile Functions</title>

<tgroup cols="3">

<thead>

<row><entry>Name</entry> <entry>Return Type</entry> <entry>Description</entry>

</indexterm>

</entry>

<entry><type>int</type></entry>

<entry>Rotate logfile</entry>

<entry>Rotateserver'slogfile</entry>

</row>

</tbody>

</tgroup>

}

}

if (PgArchPID!=0&&Shutdown==NoShutdown)

if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER)&&

PgArchPID!=0&&Shutdown==NoShutdown)

{

if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER))

{

kill(PgArchPID,SIGUSR1);

}

kill(PgArchPID,SIGUSR1);

}

if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE)&&SysLoggerPID!=0)

if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE)&&

SysLoggerPID!=0)

{

kill(SysLoggerPID,SIGUSR1);

}

PG_SETMASK(&UnBlockSig);