Description
Latches are used to guarantee consistency of non-buffer pool memory structures. The latch processed will be in update mode. Update mode is not just for UPDATE operations. It is used when SQL needs to read then modify a latch, before modification it will place an update on the data then when ready upgrade this to an exclusive latch. Note that high values in this wait do not always mean a problem (e.g. in the case of parallelism)
Resolved by
DBAs and Developers
Suggested solutions
- If this wait is experienced further details will need to be retrieved from sys.dm_os_latch_stats
- If parallelism is a common latch wait consider optimizing heavy parallel queries via indexing
Additional research
Most common latch classes and what they mean
Diagnosing and Resolving Latch Contention on SQL Server