MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
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 8.4.3.1, “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 24.8, “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.