diff options
Diffstat (limited to 'doc/src/sgml/libpq.sgml')
| -rw-r--r-- | doc/src/sgml/libpq.sgml | 52 |
1 files changed, 25 insertions, 27 deletions
diff --git a/doc/src/sgml/libpq.sgml b/doc/src/sgml/libpq.sgml index 4972a8c259..0bdb6401c3 100644 --- a/doc/src/sgml/libpq.sgml +++ b/doc/src/sgml/libpq.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.298 2010/02/16 20:58:13 momjian Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.299 2010/02/16 22:34:42 tgl Exp $ --> <chapter id="libpq"> <title><application>libpq</application> - C Library</title> @@ -307,28 +307,28 @@ <entry>Description</entry> </row> </thead> - + <tbody> - + <row> <entry><literal>disable</></entry> <entry>only try a non-<acronym>SSL</> connection</entry> </row> - + <row> <entry><literal>allow</></entry> <entry>first try a non-<acronym>SSL</> connection; if that fails, try an <acronym>SSL</> connection</entry> </row> - + <row> <entry><literal>prefer</> (default)</entry> <entry>first try an <acronym>SSL</> connection; if that fails, try a non-<acronym>SSL</> connection</entry> </row> - + <row> <entry><literal>require</></entry> <entry>only try an <acronym>SSL</> connection</entry> @@ -481,7 +481,7 @@ </para> <para> - If <literal>expand_dbname</literal> is non-zero and + If <literal>expand_dbname</literal> is non-zero and <parameter>dbname</parameter> contains an <symbol>=</symbol> sign, it is taken as a <parameter>conninfo</parameter> string in exactly the same way as if it had been passed to <function>PQconnectdb</function>(see below). Previously @@ -4111,50 +4111,48 @@ typedef struct { <productname>PostgreSQL</productname> offers asynchronous notification via the <command>LISTEN</command> and <command>NOTIFY</command> commands. A client session registers its interest in a particular - notification condition with the <command>LISTEN</command> command (and + notification channel with the <command>LISTEN</command> command (and can stop listening with the <command>UNLISTEN</command> command). All - sessions listening on a particular condition will be notified + sessions listening on a particular channel will be notified asynchronously when a <command>NOTIFY</command> command with that - condition name is executed by any session. No additional information - is passed from the notifier to the listener. Thus, typically, any - actual data that needs to be communicated is transferred through a - database table. Commonly, the condition name is the same as the - associated table, but it is not necessary for there to be any associated - table. + channel name is executed by any session. A <quote>payload</> string can + be passed to communicate additional data to the listeners. </para> <para> <application>libpq</application> applications submit - <command>LISTEN</command> and <command>UNLISTEN</command> commands as + <command>LISTEN</command>, <command>UNLISTEN</command>, + and <command>NOTIFY</command> commands as ordinary SQL commands. The arrival of <command>NOTIFY</command> messages can subsequently be detected by calling <function>PQnotifies</function>.<indexterm><primary>PQnotifies</></> </para> <para> - The function <function>PQnotifies</function> - returns the next notification from a list of unhandled - notification messages received from the server. It returns a null pointer if - there are no pending notifications. Once a notification is - returned from <function>PQnotifies</>, it is considered handled and will be - removed from the list of notifications. + The function <function>PQnotifies</function> returns the next notification + from a list of unhandled notification messages received from the server. + It returns a null pointer if there are no pending notifications. Once a + notification is returned from <function>PQnotifies</>, it is considered + handled and will be removed from the list of notifications. + <synopsis> PGnotify *PQnotifies(PGconn *conn); typedef struct pgNotify { - char *relname; /* notification condition name */ + char *relname; /* notification channel name */ int be_pid; /* process ID of notifying server process */ - char *extra; /* notification parameter */ + char *extra; /* notification payload string */ } PGnotify; </synopsis> + After processing a <structname>PGnotify</structname> object returned by <function>PQnotifies</function>, be sure to free it with <function>PQfreemem</function>. It is sufficient to free the <structname>PGnotify</structname> pointer; the <structfield>relname</structfield> and <structfield>extra</structfield> - fields do not represent separate allocations. (At present, the - <structfield>extra</structfield> field is unused and will always point - to an empty string.) + fields do not represent separate allocations. (The names of these fields + are historical; in particular, channel names need not have anything to + do with relation names.) </para> <para> |