15.7.7.26 SHOW OPEN TABLES Statement

SHOW OPEN TABLES
    [{FROM | IN} db_name]
    [LIKE 'pattern' | WHERE expr]

SHOW OPEN TABLES lists the non-TEMPORARY tables that are currently open in the table cache. See Section 10.4.3.1, “How MySQL Opens and Closes Tables”. The FROM clause, if present, restricts the tables shown to those present in the db_name database. The LIKE clause, if present, indicates which table names to match. The WHERE clause can be given to select rows using more general conditions, as discussed in Section 28.8, “Extensions to SHOW Statements”.

SHOW OPEN TABLES output has these columns:

• Database

  The database containing the table.

• Table

  The table name.

• In_use

  The number of table locks or lock requests there are for the table. For example, if one client acquires a lock for a table using LOCK TABLE t1 WRITE, In_use is 1. If another client issues LOCK TABLE t1 WRITE while the table remains locked, the client blocks, waiting for the lock, but the lock request causes In_use to be 2. If the count is zero, the table is open but not currently being used. In_use is also increased by the HANDLER ... OPEN statement and decreased by HANDLER ... CLOSE.

• Name_locked

  Whether the table name is locked. Name locking is used for operations such as dropping or renaming tables.

If you have no privileges for a table, it does not show up in the output from SHOW OPEN TABLES.