PAGELATCH_NL Wait Type in SQL Server

Part of the SQL Server Wait Types Library.
Related deep dive: PAGELATCH_EX Wait Type.

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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

1. Nothing here. For page latch analysis, work the real modes and the db:file:page evidence.

How To See It

Rank waits with Get-WaitStatistics; this entry stays at zero while its siblings tell any real story.

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