What is Latch protection in SQL Server was a reader question after my scheduler video. A latch provides short-lived internal synchronization.
A page in the buffer pool is a shared work surface. Page latches coordinate physical access as threads read or change it. Locks protect logical transaction isolation. They can remain much longer.
The buffer pool holds database pages in memory. Modified pages remain dirty until written. Write-ahead logging hardens the relevant log record before the data page write. Latches don’t replace that logging protocol.
Some latches protect structures other than buffer-pool pages. Distinguish PAGELATCH, PAGEIOLATCH and other LATCH waits. Interpret totals over a known interval with affected resources and workload context. A cumulative number alone is not an actionable diagnosis.
The two videos connect the memory example with scheduling. Keep latches, transaction locks and disk latency distinct. Each requires the appropriate evidence.
Related reading
- SQL SERVER – SQLOS Scheduler and the Process States
- Sleeping vs Suspended Process – SQL in Sixty Seconds #122
Original video
A latch is not a transaction lock, it is internal synchronization for safe structural access.
Published by Pinal Dave on SQLAuthority. More of my work at pinaldave.com.
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