MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6 The table_handles Table

The Performance Schema exposes table lock information through the table_handles table to show the table locks currently in effect for each opened table handle. table_handles reports what is recorded by the table lock instrumentation. This information shows which table handles the server has open, how they are locked, and by which sessions.

The table_handles table is read only and cannot be updated. It is autosized by default; to configure the table size, set the performance_schema_max_table_handles system variable at server startup.

Table lock instrumentation uses the wait/lock/table/sql/handler instrument, which is enabled by default.

To control table lock instrumentation state at server startup, use lines like these in your my.cnf file:

To control table lock instrumentation state at runtime, update the setup_instruments table:

The table_handles table has these columns:

TRUNCATE TABLE is not permitted for the table_handles table.