dblink_get_notify
dblink_get_notify — выдаёт асинхронные уведомления подключения
Синтаксис
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)
Описание
dblink_get_notify выдаёт уведомления либо безымянного подключения, либо подключения с заданным именем. Чтобы получать уведомления через dblink, необходимо сначала выполнить LISTEN, воспользовавшись функцией dblink_exec. За подробностями обратитесь к LISTEN и NOTIFY.
Аргументы
connnameИмя именованного подключения, уведомления которого нужно получить.
Возвращаемое значение
Возвращает setof (notify_name text, be_pid int, extra text) или пустой набор, если уведомлений нет.
Примеры
SELECT dblink_exec('LISTEN virtual');
dblink_exec
-------------
LISTEN
(1 row)
SELECT * FROM dblink_get_notify();
notify_name | be_pid | extra
-------------+--------+-------
(0 rows)
NOTIFY virtual;
NOTIFY
SELECT * FROM dblink_get_notify();
notify_name | be_pid | extra
-------------+--------+-------
virtual | 1229 |
(1 row)21.4. Database Configuration
Recall from Chapter 18 that the Postgres Pro server provides a large number of run-time configuration variables. You can set database-specific default values for many of these settings.
For example, if for some reason you want to disable the GEQO optimizer for a given database, you'd ordinarily have to either disable it for all databases or make sure that every connecting client is careful to issue SET geqo TO off. To make this setting the default within a particular database, you can execute the command:
ALTER DATABASE mydb SET geqo TO off;
This will save the setting (but not set it immediately). In subsequent connections to this database it will appear as though SET geqo TO off; had been executed just before the session started. Note that users can still alter this setting during their sessions; it will only be the default. To undo any such setting, use ALTER DATABASE . dbname RESET varname