GLOBAL_THREAD_WAIT_STATUS

GLOBAL_THREAD_WAIT_STATUS allows you to test the block waiting status of backend threads and auxiliary threads on all nodes. For details about events, see Appendices-Table 1, Appendices-Table 2, Appendices-Table 3, and Appendices-Table 4.

In GLOBAL_THREAD_WAIT_STATUS, you can see all the call hierarchy relationships between threads of the SQL statements on all nodes in MogDB, and the block waiting status for each thread. With this view, you can easily locate the causes of process hang and similar issues.

The definitions of GLOBAL_THREAD_WAIT_STATUS and THREAD_WAIT_STATUS are the same, because the GLOBAL_THREAD_WAIT_STATUS view is essentially the query summary of the THREAD_WAIT_STATUS view on each node in MogDB.

Table 1 GLOBAL_THREAD_WAIT_STATUS columns

Name	Type	Description
node_name	text	Node name
db_name	text	Database name
thread_name	text	Thread name
query_id	bigint	Query ID. The value of this column is the same as that of debug_query_id.
tid	bigint	Thread ID of the current thread
sessionid	bigint	Session ID
lwtid	integer	Lightweight thread ID of the current thread
psessionid	bigint	Parent thread of the streaming thread
tlevel	integer	Level of the streaming thread
smpid	integer	Concurrent thread ID
wait_status	text	Waiting status of the current thread. For details about the waiting status, see Appendices-Table 2.
wait_event	text	If wait_status is acquire lock, acquire lwlock, or wait io, this column describes the lock, lightweight lock, and I/O information, respectively. If wait_status is not any of the three values, this column is empty.