Latches

The Latch band shows page latches acquired and released during the query - the lightweight, short-lived locks SQL Server uses to protect a page's in-memory consistency while it is being read or modified, distinct from the row/page/object Locks used for transaction isolation.

A BUF SH latch is what identifies a buffer read - the page is already in memory, and the latch just pins it for the duration of the read. A latch suspend - the engine waiting for a latch to become available - is also the first step of a disk read, ahead of the file read and physical page read.

TIP

Latches are held very briefly and in large numbers, so capturing them (via the Events menu) adds overhead to the trace. Turn them off if you don't need latch-level detail.