{
    "mode": "man",
    "parameter": "LISTEN",
    "section": "7",
    "url": "https://www.chedong.com/phpMan.php/man/LISTEN/7/json",
    "generated": "2026-06-16T10:02:14Z",
    "synopsis": "LISTEN channel",
    "sections": {
        "NAME": {
            "content": "LISTEN - listen for a notification\n",
            "subsections": []
        },
        "SYNOPSIS": {
            "content": "LISTEN channel\n",
            "subsections": []
        },
        "DESCRIPTION": {
            "content": "LISTEN registers the current session as a listener on the notification channel named channel.\nIf the current session is already registered as a listener for this notification channel,\nnothing is done.\n\nWhenever the command NOTIFY channel is invoked, either by this session or another one\nconnected to the same database, all the sessions currently listening on that notification\nchannel are notified, and each will in turn notify its connected client application.\n\nA session can be unregistered for a given notification channel with the UNLISTEN command. A\nsession's listen registrations are automatically cleared when the session ends.\n\nThe method a client application must use to detect notification events depends on which\nPostgreSQL application programming interface it uses. With the libpq library, the application\nissues LISTEN as an ordinary SQL command, and then must periodically call the function\nPQnotifies to find out whether any notification events have been received. Other interfaces\nsuch as libpgtcl provide higher-level methods for handling notify events; indeed, with\nlibpgtcl the application programmer should not even issue LISTEN or UNLISTEN directly. See\nthe documentation for the interface you are using for more details.\n",
            "subsections": []
        },
        "PARAMETERS": {
            "content": "channel\nName of a notification channel (any identifier).\n",
            "subsections": []
        },
        "NOTES": {
            "content": "LISTEN takes effect at transaction commit. If LISTEN or UNLISTEN is executed within a\ntransaction that later rolls back, the set of notification channels being listened to is\nunchanged.\n\nA transaction that has executed LISTEN cannot be prepared for two-phase commit.\n\nThere is a race condition when first setting up a listening session: if\nconcurrently-committing transactions are sending notify events, exactly which of those will\nthe newly listening session receive? The answer is that the session will receive all events\ncommitted after an instant during the transaction's commit step. But that is slightly later\nthan any database state that the transaction could have observed in queries. This leads to\nthe following rule for using LISTEN: first execute (and commit!) that command, then in a new\ntransaction inspect the database state as needed by the application logic, then rely on\nnotifications to find out about subsequent changes to the database state. The first few\nreceived notifications might refer to updates already observed in the initial database\ninspection, but this is usually harmless.\n\nNOTIFY(7) contains a more extensive discussion of the use of LISTEN and NOTIFY.\n",
            "subsections": []
        },
        "EXAMPLES": {
            "content": "Configure and execute a listen/notify sequence from psql:\n\nLISTEN virtual;\nNOTIFY virtual;\nAsynchronous notification \"virtual\" received from server process with PID 8448.\n",
            "subsections": []
        },
        "COMPATIBILITY": {
            "content": "There is no LISTEN statement in the SQL standard.\n",
            "subsections": []
        },
        "SEE ALSO": {
            "content": "NOTIFY(7), UNLISTEN(7)\n\n\n\nPostgreSQL 14.23                                2026                                       LISTEN(7)",
            "subsections": []
        }
    },
    "summary": "LISTEN - listen for a notification",
    "flags": [],
    "examples": [
        "Configure and execute a listen/notify sequence from psql:",
        "LISTEN virtual;",
        "NOTIFY virtual;",
        "Asynchronous notification \"virtual\" received from server process with PID 8448."
    ],
    "see_also": [
        {
            "name": "NOTIFY",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/NOTIFY/7/json"
        },
        {
            "name": "UNLISTEN",
            "section": "7",
            "url": "https://www.chedong.com/phpMan.php/man/UNLISTEN/7/json"
        }
    ]
}