PAGELATCH_NL is the wait type for a Null (NL) mode latch on an in-memory data file page. Null mode is a non-acquiring placeholder, and the wait type exists so the page latch family covers all latch modes symmetrically. It is not used in practice.
Documented here so the lookup dead-ends usefully.
Is It a Problem?
No, and you should never see it accumulate. Any tool reporting meaningful PAGELATCH_NL time deserves scepticism.
Page latch trouble on real systems is PAGELATCH_SH/UP/EX territory, usually spelled t-e-m-p-d-b: allocation bitmap contention with its 2:1:1/2:1:2/2:1:3 signature in sys.dm_os_waiting_tasks, covered in depth by the tempdb contention pillar.
Common Causes
- None; the mode is a placeholder.
What To Do
- Nothing here. For page latch analysis, work the real modes and the
db:file:pageevidence.
How To See It
Rank waits with Get-WaitStatistics; this entry stays at zero while its siblings tell any real story.
PAGELATCH_NL is background noise on a healthy instance. If you are chasing a real problem, start with the waits that actually cost you time.
- The waits that usually matter, ranked, with what each one is telling you.
- PAGELATCH_EX Wait Type, the closest wait worth investigating when this one is high.
- Performance & Troubleshooting, the scripts and guides for this part of the stack.
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