MySQL 8.4 Reference Manual Including MySQL NDB Cluster 8.4
The tp_connections table contains one row
per connection managed by the Thread Pool plugin. Each row
provides information about the current state of a thread pool
connection.
The tp_connections table contains the
following rows:
CONNECTION_ID
The connection ID as reported by
SELECT
CONNECTION_ID().
TP_GROUP_ID
The index of the thread group in the global array. This
column and TP_PROCESSING_THREAD_NUMBER
serve as a foreign key into the
tp_thread_state table.
TP_PROCESSING_THREAD_NUMBER
This may be NULL if no thread is currently attached to the connection.
THREAD_ID
The Performance Schema thread ID.
STATE
The connection state; this is one of
Established, Armed,
Queued, Waiting for
Credit, Attached,
Expired, or Killed.
ACTIVE_FLAG
When this is 0, the connection is not
attached to any worker thread.
KILLED_STATE
Reports the current stage in the process of killing the connection.
CLEANUP_STATE
Reports the current stage in the cleanup process when closing the connection.
TIME_OF_LAST_EVENT_COMPLETION
Timestamp showing when the connection last processed a request.
TIME_OF_EXPIRY
Timestamp showing when an idle connection will expire if
no new request arrives before then; this is
NULL when the thread is currently
processing a request.
TIME_OF_ADD
Timestamp showing when the connection was added to the thread pool's connection request queue.
TIME_OF_POP
Timestamp showing when the connection was dequeued (popped) from the queue by a connection handler thread.
TIME_OF_ARM
Timestamp showing when the connection file descriptor was
last added to the set monitored by
poll() or epoll().
CONNECT_HANDLER_INDEX
The index of the connection handler thread in the group which processed the connection request; a higher number means the connection load has triggered the creation of additional connection handler threads.
TYPE
The connection type; this is one of
User,
Admin_interface or
Admin_privilege;
Admin_privilege means that this
connection had been using the normal interface, but was
placed in the admin group due to the
user having the
TP_CONNECTION_ADMIN
privilege.
DIRECT_QUERY_EVENTS
The number of queries executed directly by this connection.
QUEUED_QUERY_EVENTS
The number of queued queries executed by this connection.
TIME_OF_EVENT_ARRIVAL
A timestamp showing when poll_wait()
returns with an event for the connection; this value is
needed to calculate MANAGEMENT_TIME.
MANAGEMENT_TIME
The accumulated time between the return from waiting on file descriptors; this includes the time spent queued for queries which are not executed directly.