LATCH_EX
Occurs when waiting for an EX (exclusive) latch. This does not include buffer latches or transaction mark latches.
Detailed Description​
Latches are lightweight, fast methods of managing concurrency on a specific resource. This group of latches are seen in management of pages that have already been read into memory.
Books online says "Occurs when waiting for an EX (exclusive) latch. This does not include buffer latches or transaction mark latches. A listing of LATCH_* waits is available in sys.dm_os_latch_stats. Note that sys.dm_os_latch_stats groups LATCH_NL, LATCH_SH, LATCH_UP, LATCH_EX, and LATCH_DT waits together".
How to reduce this wait​
There is a great article in sqlskills.com under the LATCH_EX page which gives a breakdown of the steps needed to identify the latch which you are waiting on - as although the wait time is shown, it does not identify the specific latch being contended for.
Additional Links​
- Microsoft Docs - sys.dm_os_wait_stats (Transact-SQL)
- sqlskills.com - LATCH_SH
- sqlshack.com - All about latches
Search online​
If this article doesn't have the information you need you can try searching online. Remember, you can contribute suggestions to this page.