SHOW OPEN TABLES [FROM db_name] [LIKE 'pattern' | WHERE expr]
SHOW OPEN TABLES
lists the non-TEMPORARY
tables that are currently open in the table cache. See http://dev.mysql.com/doc/refman/5.1/en/table-cache.html.
The FROM
and LIKE
clauses may be used.
The FROM
clause, if present, restricts the tables shown to those present in the db_name
database.
The LIKE
clause, if present on its own, indicates which table names to match. The WHERE
and LIKE
clauses can be given to select rows using more general conditions, as discussed in Extended SHOW.
The following information is returned:
Column | Description |
---|---|
Database | Database name. |
Name | Table name. |
In_use | Number of table instances being used. |
Name_locked |
1 if the table is name-locked, e.g. if it is being dropped or renamed, otherwise 0 . |
Before MariaDB 5.5, each use of, for example, LOCK TABLE ... WRITE would increment In_use
for that table. With the implementation of the metadata locking improvements in MariaDB 5.5, LOCK TABLE... WRITE
acquires a strong MDL lock, and concurrent connections will wait on this MDL lock, so any subsequent LOCK TABLE... WRITE
will not increment In_use
.
SHOW OPEN TABLES; +----------+---------------------------+--------+-------------+ | Database | Table | In_use | Name_locked | +----------+---------------------------+--------+-------------+ ... | test | xjson | 0 | 0 | | test | jauthor | 0 | 0 | | test | locks | 1 | 0 | ... +----------+---------------------------+--------+-------------+
© 2019 MariaDB
Licensed under the Creative Commons Attribution 3.0 Unported License and the GNU Free Documentation License.
https://mariadb.com/kb/en/show-open-tables/