> For the complete documentation index, see [llms.txt](https://docs.postgresql.tw/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.postgresql.tw/appendixes/contrib/pgrowlocks.md).

# F.31. pgrowlocks — show a table's row locking information \#

[F.31.1. Overview](#PGROWLOCKS-OVERVIEW)

[F.31.2. Sample Output](#PGROWLOCKS-SAMPLE-OUTPUT)

[F.31.3. Author](#PGROWLOCKS-AUTHOR)

The `pgrowlocks` module provides a function to show row locking information for a specified table.

By default use is restricted to superusers, roles with privileges of the `pg_stat_scan_tables` role, and users with `SELECT` permissions on the table.

## F.31.1. Overview [#](#PGROWLOCKS-OVERVIEW)

```

pgrowlocks(text) returns setof record
```

The parameter is the name of a table. The result is a set of records, with one row for each locked row within the table. The output columns are shown in [Table F.21](#PGROWLOCKS-COLUMNS).

**Table F.21. `pgrowlocks` Output Columns**

| Name         | Type        | Description                                                                                                                                                       |
| ------------ | ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `locked_row` | `tid`       | Tuple ID (TID) of locked row                                                                                                                                      |
| `locker`     | `xid`       | Transaction ID of locker, or multixact ID if multitransaction; see [Section 67.1](/internals/transactions/transaction-id.md)                                      |
| `multi`      | `boolean`   | True if locker is a multitransaction                                                                                                                              |
| `xids`       | `xid[]`     | Transaction IDs of lockers (more than one if multitransaction)                                                                                                    |
| `modes`      | `text[]`    | Lock mode of lockers (more than one if multitransaction), an array of `For Key Share`, `For Share`, `For No Key Update`, `No Key Update`, `For Update`, `Update`. |
| `pids`       | `integer[]` | Process IDs of locking backends (more than one if multitransaction)                                                                                               |

<br>

`pgrowlocks` takes `AccessShareLock` for the target table and reads each row one by one to collect the row locking information. This is not very speedy for a large table. Note that:

1. If an `ACCESS EXCLUSIVE` lock is taken on the table, `pgrowlocks` will be blocked.
2. `pgrowlocks` is not guaranteed to produce a self-consistent snapshot. It is possible that a new row lock is taken, or an old lock is freed, during its execution.

`pgrowlocks` does not show the contents of locked rows. If you want to take a look at the row contents at the same time, you could do something like this:

```

SELECT * FROM accounts AS a, pgrowlocks('accounts') AS p
  WHERE p.locked_row = a.ctid;
```

Be aware however that such a query will be very inefficient.

## F.31.2. Sample Output [#](#PGROWLOCKS-SAMPLE-OUTPUT)

```

=# SELECT * FROM pgrowlocks('t1');
 locked_row | locker | multi | xids  |     modes      |  pids
------------+--------+-------+-------+----------------+--------
 (0,1)      |    609 | f     | {609} | {"For Share"}  | {3161}
 (0,2)      |    609 | f     | {609} | {"For Share"}  | {3161}
 (0,3)      |    607 | f     | {607} | {"For Update"} | {3107}
 (0,4)      |    607 | f     | {607} | {"For Update"} | {3107}
(4 rows)
```

## F.31.3. Author [#](#PGROWLOCKS-AUTHOR)

Tatsuo Ishii

***

原文：[PostgreSQL 18.6 Documentation](https://www.postgresql.org/docs/18/pgrowlocks.html)（英文原文，待翻譯）


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