Documentation Home
MySQL 5.7 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 35.6Mb
PDF (A4) - 35.6Mb
PDF (RPM) - 34.7Mb
EPUB - 8.7Mb
HTML Download (TGZ) - 8.5Mb
HTML Download (Zip) - 8.5Mb
HTML Download (RPM) - 7.3Mb
Eclipse Doc Plugin (TGZ) - 9.4Mb
Eclipse Doc Plugin (Zip) - 11.5Mb
Man Pages (TGZ) - 203.5Kb
Man Pages (Zip) - 310.2Kb
Info (Gzip) - 3.3Mb
Info (Zip) - 3.3Mb
Excerpts from this Manual

23.9.12.2 The table_handles Table

As of MySQL 5.7.3, 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.

The table_handles table has these columns:

  • OBJECT_TYPE

    The table opened by a table handle.

  • OBJECT_SCHEMA

    The schema that contains the object.

  • OBJECT_NAME

    The name of the instrumented object.

  • OBJECT_INSTANCE_BEGIN

    The table handle address in memory.

  • OWNER_THREAD_ID

    The thread owning the table handle.

  • OWNER_EVENT_ID

    The event which caused the table handle to be opened.

  • INTERNAL_LOCK

    The table lock used at the SQL level. The value is one of READ, READ WITH SHARED LOCKS, READ HIGH PRIORITY, READ NO INSERT, WRITE ALLOW WRITE, WRITE CONCURRENT INSERT, WRITE LOW PRIORITY, or WRITE. For information about these lock types, see the include/thr_lock.h source file.

  • EXTERNAL_LOCK

    The table lock used at the storage engine level. The value is one of READ EXTERNAL or WRITE EXTERNAL.


User Comments
Sign Up Login You must be logged in to post a comment.