Effective memory management is crucial for optimal SQL Server performance. Monitoring memory usage helps database administrators identify potential issues and tune database performance. We’ll explore two essential queries that provide insights into how SQL Server uses memory.

Prerequisites:

• Basic understanding of Microsoft SQL Server
• SQL Server Management Studio (SSMS) installed and connected to your SQL Server instance

Query 1: SQL Server Memory Information

-- SQL Server memory information 
SELECT
     physical_memory_in_use_kb / 1024 / 1024 AS [physical_memory_GB],
     total_virtual_address_space_kb / 1024 / 1024 AS [total_VAS_GB],
     virtual_address_space_available_kb / 1024 / 1024 AS [VAS_available_GB],
     memory_utilization_percentage 
FROM sys.dm_os_process_memory;

Explanation:

This query retrieves various memory-related metrics from sys.dm_os_process_memory, offering an overview of SQL Server memory usage.

• physical_memory_in_use_GB: Physical memory used by SQL Server in gigabytes.
• total_virtual_address_space_GB: Total virtual address space in gigabytes.
• virtual_address_space_available_GB: Available virtual address space in gigabytes.
• memory_utilization_percentage: Percentage of memory utilization.

Query 2: Memory Used by Each Database

-- Memory used by each database
SELECT DB_NAME(database_id) AS DatabaseName,
       COUNT(1) * 8 / 1024 AS MBUsed,
       COUNT(1) * 8 / 1024 / 1024 AS GBUsed
FROM sys.dm_os_buffer_descriptors
GROUP BY database_id
ORDER BY COUNT(*) * 8 / 1024 DESC;

Explanation:

• DB_NAME(database_id): This function retrieves the name of each database based on its database_id.
• COUNT(1): Counts the number of 8 KB pages in the SQL Server buffer for each database.
• * 8 / 1024: Converts the count from pages to megabytes (MB).
• * 8 / 1024 / 1024: Converts the count from megabytes to gigabytes (GB).
• sys.dm_os_buffer_descriptors: A view that provides information about the buffer pool in SQL Server.
• GROUP BY database_id: Groups the results by database, allowing you to see memory usage per database.
• ORDER BY COUNT(*) * 8 / 1024 DESC: Orders the results in descending order based on the memory used in MB.

These two SQL Server queries help you gain insights into memory usage. Monitoring memory is essential for database administrators to ensure optimal performance and troubleshoot potential issues. By using these queries, you can keep an eye on database memory usage and make informed decisions to improve SQL Server performance.