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)

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DBAs and Developers

Suggested solutions

  1. If this wait is experienced further details will need to be retrieved from sys.dm_os_latch_stats
  2. 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

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