Summary: Use the sys.dm_os_memory_clerks DMV to identify which components—such as the Buffer Pool, Plan Cache, or Columnstore—are consuming the most memory in your SQL Server instance.
Identify Top Memory Consumers via SQL Server Memory Clerks
If your SQL Server is experiencing high memory pressure, the first step is to identify which internal component is "hogging" the RAM. SQL Server uses Memory Clerks to manage allocations for different features like the Buffer Pool, Plan Cache, and CLR.
This query provides a clear breakdown of memory usage by various clerk types, ordered by the highest consumption, helping you pinpoint exactly where the memory is going.
Top 10 Memory Clerk Usage Script
-- Get top 10 memory consumers by Clerk Type
SELECT TOP (10)
mc.[type] AS [Memory Clerk Type],
CAST((SUM(mc.pages_kb) / 1024.0) AS DECIMAL(15, 2)) AS [Memory Usage (MB)]
FROM sys.dm_os_memory_clerks AS mc WITH (NOLOCK)
GROUP BY mc.[type]
ORDER BY SUM(mc.pages_kb) DESC
OPTION (RECOMPILE);
Understanding Common Clerk Types
- MEMORYCLERK_SQLBUFFERPOOL: This is usually the largest, representing the data cache.
- CACHESTORE_SQLCP: The SQL Plan Cache (ad-hoc queries).
- CACHESTORE_OBJCP: Object Plans (stored procedures, functions).
- MEMORYCLERK_SQLOPTIMIZER: Memory used during the query optimization process.
This query leverages the
sys.dm_os_memory_clerks
DMV. For more in-depth exploration of performance tuning, check out these related articles:
- Understanding Memory Grants Pending
- Retrieving Hardware Information
- Advanced Memory Clerk Auditing
- Finding SQL Server Memory Dumps
Seeing unexpected memory usage? Large amounts of memory in CACHESTORE_SQLCP might indicate a need to enable "Optimize for Ad-hoc Workloads"!
