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Implement dblink_get_notify().

Browse Source 
Adds the ability to retrieve async notifications using dblink,
via the addition of the function dblink_get_notify(). Original patch
by Marcus Kempe, suggestions by Tom Lane and Alvaro Herrera, patch
review and adjustments by Joe Conway.
REL8_5_ALPHA1_BRANCH
Joe Conway 16 years ago
parent 16f3cf8c0c
commit f4095b4c4b
7 changed files with 253 additions and 5 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 85
      contrib/dblink/dblink.c
  2. 3
      contrib/dblink/dblink.h
  3. 21
      contrib/dblink/dblink.sql.in
  4. 51
      contrib/dblink/expected/dblink.out
  5. 17
      contrib/dblink/sql/dblink.sql
  6. 6
      contrib/dblink/uninstall_dblink.sql
  7. 75
      doc/src/sgml/dblink.sgml

85
contrib/dblink/dblink.c
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@ -8,7 +8,7 @@
* Darko Prenosil <Darko.Prenosil@finteh.hr>
* Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
*
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.82 2009/06/11 14:48:50 momjian Exp $
* $PostgreSQL: pgsql/contrib/dblink/dblink.c,v 1.83 2009/08/05 16:11:07 joe Exp $
* Copyright (c) 2001-2009, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
@ -1635,6 +1635,89 @@ dblink_current_query(PG_FUNCTION_ARGS)
PG_RETURN_DATUM(current_query(fcinfo));
}
/*
* Retrieve async notifications for a connection.
*
* Returns an setof record of notifications, or an empty set if none recieved.
* Can optionally take a named connection as parameter, but uses the unnamed connection per default.
*
*/
#define DBLINK_NOTIFY_COLS 3
PG_FUNCTION_INFO_V1(dblink_get_notify);
Datum
dblink_get_notify(PG_FUNCTION_ARGS)
{
PGconn *conn = NULL;
remoteConn *rconn = NULL;
PGnotify *notify;
ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
TupleDesc tupdesc;
Tuplestorestate *tupstore;
MemoryContext per_query_ctx;
MemoryContext oldcontext;
DBLINK_INIT;
if (PG_NARGS() == 1)
DBLINK_GET_NAMED_CONN;
else
conn = pconn->conn;
/* create the tuplestore */
per_query_ctx = rsinfo->econtext->ecxt_per_query_memory;
oldcontext = MemoryContextSwitchTo(per_query_ctx);
tupdesc = CreateTemplateTupleDesc(DBLINK_NOTIFY_COLS, false);
TupleDescInitEntry(tupdesc, (AttrNumber) 1, "notify_name",
TEXTOID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 2, "be_pid",
INT4OID, -1, 0);
TupleDescInitEntry(tupdesc, (AttrNumber) 3, "extra",
TEXTOID, -1, 0);
tupstore = tuplestore_begin_heap(true, false, work_mem);
rsinfo->returnMode = SFRM_Materialize;
rsinfo->setResult = tupstore;
rsinfo->setDesc = tupdesc;
MemoryContextSwitchTo(oldcontext);
PQconsumeInput(conn);
while ((notify = PQnotifies(conn)) != NULL)
{
Datum values[DBLINK_NOTIFY_COLS];
bool nulls[DBLINK_NOTIFY_COLS];
memset(values, 0, sizeof(values));
memset(nulls, 0, sizeof(nulls));
if (notify->relname != NULL)
values[0] = CStringGetTextDatum(notify->relname);
else
nulls[0] = true;
values[1] = Int32GetDatum(notify->be_pid);
if (notify->extra != NULL)
values[2] = CStringGetTextDatum(notify->extra);
else
nulls[2] = true;
/* switch to appropriate context while storing the tuple */
MemoryContextSwitchTo(per_query_ctx);
tuplestore_putvalues(tupstore, tupdesc, values, nulls);
MemoryContextSwitchTo(oldcontext);
PQfreemem(notify);
PQconsumeInput(conn);
}
/* clean up and return the tuplestore */
tuplestore_donestoring(tupstore);
return (Datum) 0;
}
/*************************************************************
* internal functions
*/

3
contrib/dblink/dblink.h
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@ -8,7 +8,7 @@
* Darko Prenosil <Darko.Prenosil@finteh.hr>
* Shridhar Daithankar <shridhar_daithankar@persistent.co.in>
*
* $PostgreSQL: pgsql/contrib/dblink/dblink.h,v 1.22 2009/06/09 17:41:02 tgl Exp $
* $PostgreSQL: pgsql/contrib/dblink/dblink.h,v 1.23 2009/08/05 16:11:07 joe Exp $
* Copyright (c) 2001-2009, PostgreSQL Global Development Group
* ALL RIGHTS RESERVED;
*
@ -57,5 +57,6 @@ extern Datum dblink_build_sql_insert(PG_FUNCTION_ARGS);
extern Datum dblink_build_sql_delete(PG_FUNCTION_ARGS);
extern Datum dblink_build_sql_update(PG_FUNCTION_ARGS);
extern Datum dblink_current_query(PG_FUNCTION_ARGS);
extern Datum dblink_get_notify(PG_FUNCTION_ARGS);
#endif /* DBLINK_H */

21
contrib/dblink/dblink.sql.in
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@ -1,4 +1,4 @@
/* $PostgreSQL: pgsql/contrib/dblink/dblink.sql.in,v 1.18 2009/06/09 17:41:02 tgl Exp $ */
/* $PostgreSQL: pgsql/contrib/dblink/dblink.sql.in,v 1.19 2009/08/05 16:11:07 joe Exp $ */
-- Adjust this setting to control where the objects get created.
SET search_path = public;
@ -202,3 +202,22 @@ CREATE OR REPLACE FUNCTION dblink_error_message(text)
RETURNS text
AS 'MODULE_PATHNAME', 'dblink_error_message'
LANGUAGE C STRICT;
CREATE OR REPLACE FUNCTION dblink_get_notify(
OUT notify_name TEXT,
OUT be_pid INT4,
OUT extra TEXT
)
RETURNS setof record
AS 'MODULE_PATHNAME', 'dblink_get_notify'
LANGUAGE C STRICT;
CREATE OR REPLACE FUNCTION dblink_get_notify(
conname TEXT,
OUT notify_name TEXT,
OUT be_pid INT4,
OUT extra TEXT
)
RETURNS setof record
AS 'MODULE_PATHNAME', 'dblink_get_notify'
LANGUAGE C STRICT;

51
contrib/dblink/expected/dblink.out
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@ -827,3 +827,54 @@ DROP USER dblink_regression_test;
DROP USER MAPPING FOR public SERVER fdtest;
DROP SERVER fdtest;
DROP FOREIGN DATA WRAPPER postgresql;
-- test asynchronous notifications
SELECT dblink_connect('dbname=contrib_regression');
dblink_connect
----------------
OK
(1 row)
--should return listen
SELECT dblink_exec('LISTEN regression');
dblink_exec
-------------
LISTEN
(1 row)
--should return listen
SELECT dblink_exec('LISTEN foobar');
dblink_exec
-------------
LISTEN
(1 row)
SELECT dblink_exec('NOTIFY regression');
dblink_exec
-------------
NOTIFY
(1 row)
SELECT dblink_exec('NOTIFY foobar');
dblink_exec
-------------
NOTIFY
(1 row)
SELECT notify_name, be_pid = (select t.be_pid from dblink('select pg_backend_pid()') as t(be_pid int)) AS is_self_notify, extra from dblink_get_notify();
notify_name | is_self_notify | extra
-------------+----------------+-------
regression | t |
foobar | t |
(2 rows)
SELECT * from dblink_get_notify();
notify_name | be_pid | extra
-------------+--------+-------
(0 rows)
SELECT dblink_disconnect();
dblink_disconnect
-------------------
OK
(1 row)

17
contrib/dblink/sql/dblink.sql
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@ -389,3 +389,20 @@ DROP USER dblink_regression_test;
DROP USER MAPPING FOR public SERVER fdtest;
DROP SERVER fdtest;
DROP FOREIGN DATA WRAPPER postgresql;
-- test asynchronous notifications
SELECT dblink_connect('dbname=contrib_regression');
--should return listen
SELECT dblink_exec('LISTEN regression');
--should return listen
SELECT dblink_exec('LISTEN foobar');
SELECT dblink_exec('NOTIFY regression');
SELECT dblink_exec('NOTIFY foobar');
SELECT notify_name, be_pid = (select t.be_pid from dblink('select pg_backend_pid()') as t(be_pid int)) AS is_self_notify, extra from dblink_get_notify();
SELECT * from dblink_get_notify();
SELECT dblink_disconnect();

6
contrib/dblink/uninstall_dblink.sql
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@ -1,4 +1,4 @@
/* $PostgreSQL: pgsql/contrib/dblink/uninstall_dblink.sql,v 1.7 2008/04/05 02:26:14 momjian Exp $ */
/* $PostgreSQL: pgsql/contrib/dblink/uninstall_dblink.sql,v 1.8 2009/08/05 16:11:07 joe Exp $ */
-- Adjust this setting to control where the objects get dropped.
SET search_path = public;
@ -76,3 +76,7 @@ DROP FUNCTION dblink_get_result(text, boolean);
DROP FUNCTION dblink_is_busy(text);
DROP FUNCTION dblink_send_query(text, text);
DROP FUNCTION dblink_get_notify();
DROP FUNCTION dblink_get_notify(text);

75
doc/src/sgml/dblink.sgml
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@ -1,4 +1,4 @@
<!-- $PostgreSQL: pgsql/doc/src/sgml/dblink.sgml,v 1.8 2009/06/18 14:34:36 petere Exp $ -->
<!-- $PostgreSQL: pgsql/doc/src/sgml/dblink.sgml,v 1.9 2009/08/05 16:11:07 joe Exp $ -->
<sect1 id="dblink">
<title>dblink</title>
@ -1260,6 +1260,79 @@ SELECT *
</refsect1>
</refentry>
<refentry id="CONTRIB-DBLINK-GET-NOTIFY">
<refnamediv>
<refname>dblink_get_notify</refname>
<refpurpose>retrieve async notifications on a connection</refpurpose>
</refnamediv>
<refsynopsisdiv>
<synopsis>
dblink_get_notify() returns setof (notify_name text, be_pid int, extra text)
dblink_get_notify(text connname) returns setof (notify_name text, be_pid int, extra text)
</synopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<function>dblink_get_notify</> retrieves notifications on either
the unnamed connection, or on a named connection if specified.
To receive notifications via dblink, <function>LISTEN</> must
first be issued, using <function>dblink_exec</>.
For details see <xref linkend="sql-listen"> and <xref linkend="sql-notify">.
</para>
</refsect1>
<refsect1>
<title>Arguments</title>
<variablelist>
<varlistentry>
<term><parameter>conname</parameter></term>
<listitem>
<para>
The name of a named connection to get notifications on.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>Returns setof (notify_name text, be_pid int, extra text), or an empty set if none.</para>
</refsect1>
<refsect1>
<title>Example</title>
<programlisting>
test=# SELECT dblink_exec('LISTEN virtual');
dblink_exec
-------------
LISTEN
(1 row)
test=# SELECT * FROM dblink_get_notify();
notify_name | be_pid | extra
-------------+--------+-------
(0 rows)
test=# NOTIFY virtual;
NOTIFY
SELECT * FROM dblink_get_notify();
notify_name | be_pid | extra
-------------+--------+-------
virtual | 1229 |
(1 row)
</programlisting>
</refsect1>
</refentry>
<refentry id="CONTRIB-DBLINK-GET-RESULT">
<refmeta>
<refentrytitle>dblink_get_result</refentrytitle>

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