SQL Server 的内存使用情况

Question

我如何在生产框中检查我的 SQL 服务器的内存使用情况。我正在使用 SQL Server 2016。当我检查任务管理器时，它显示在 90% 以上。我不认为这是 sql server 的真实内存使用情况。

我有一个 SQL 性能工具 grafana，它显示的 CPU 使用率比我在任务管理器中看到的少得多。我检查了资源监视器，可以看到平均 CPU 值。我对 SQL 服务器内存使用情况感到困惑。我正在尝试确定内存压力是否是我的某些问题的一个问题。

有人可以直接给出一个好的/正确的解释。

Answer 1

“我正在尝试确定内存压力是否是我的某些问题的一个问题。”

非常有用的脚本：https : //github.com/ktaranov/sqlserver-kit/blob/master/Scripts/SQLServer_Memory_Information.sql

您会看到详细的内存使用情况：

https://www.sqlskills.com/blogs/glenn/sql-server-diagnostic-information-queries-for-november-2017/ SQL Server 2017 诊断信息查询：
见评论

-- Page Life Expectancy (PLE) value for each NUMA node in current instance  (Query 46) (PLE by NUMA Node)
SELECT @@SERVERNAME AS [Server Name], RTRIM([object_name]) AS [Object Name], instance_name, cntr_value AS [Page Life Expectancy]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Buffer Node%' -- Handles named instances
AND counter_name = N'Page life expectancy' OPTION (RECOMPILE);
------

-- PLE is a good measurement of internal memory pressure
-- Higher PLE is better. Watch the trend over time, not the absolute value

（查询 14）

-- Good basic information about OS memory amounts and state  (Query 14) (System Memory)
SELECT total_physical_memory_kb/1024 AS [Physical Memory (MB)], 
       available_physical_memory_kb/1024 AS [Available Memory (MB)], 
       total_page_file_kb/1024 AS [Total Page File (MB)], 
       available_page_file_kb/1024 AS [Available Page File (MB)], 
       system_cache_kb/1024 AS [System Cache (MB)],
       system_memory_state_desc AS [System Memory State]
FROM sys.dm_os_sys_memory WITH (NOLOCK) OPTION (RECOMPILE);
------

-- You want to see "Available physical memory is high" for System Memory State
-- This indicates that you are not under external memory pressure

-- Possible System Memory State values:
-- Available physical memory is high
-- Physical memory usage is steady
-- Available physical memory is low
-- Available physical memory is running low
-- Physical memory state is transitioning

(47)

-- Memory Grants Pending value for current instance  (Query 47) (Memory Grants Pending)
SELECT @@SERVERNAME AS [Server Name], RTRIM([object_name]) AS [Object Name], cntr_value AS [Memory Grants Pending]
FROM sys.dm_os_performance_counters WITH (NOLOCK)
WHERE [object_name] LIKE N'%Memory Manager%' -- Handles named instances
AND counter_name = N'Memory Grants Pending' OPTION (RECOMPILE);
------

-- Run multiple times, and run periodically if you suspect you are under memory pressure
-- Memory Grants Pending above zero for a sustained period is a very strong indicator of internal memory pressure

(62)

-- Top Cached SPs By Total Logical Reads. Logical reads relate to memory pressure  (Query 62) (SP Logical Reads)
SELECT TOP(25) p.name AS [SP Name], qs.total_logical_reads AS [TotalLogicalReads], 
qs.total_logical_reads/qs.execution_count AS [AvgLogicalReads],qs.execution_count, 
ISNULL(qs.execution_count/DATEDIFF(Minute, qs.cached_time, GETDATE()), 0) AS [Calls/Minute], 
qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],
CASE WHEN CONVERT(nvarchar(max), qp.query_plan) LIKE N'%<MissingIndexes>%' THEN 1 ELSE 0 END AS [Has Missing Index], 
FORMAT(qs.last_execution_time, 'yyyy-MM-dd HH:mm:ss', 'en-US') AS [Last Execution Time], 
FORMAT(qs.cached_time, 'yyyy-MM-dd HH:mm:ss', 'en-US') AS [Plan Cached Time]
-- ,qp.query_plan AS [Query Plan] -- Uncomment if you want the Query Plan
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) AS qp
WHERE qs.database_id = DB_ID()
AND DATEDIFF(Minute, qs.cached_time, GETDATE()) > 0
ORDER BY qs.total_logical_reads DESC OPTION (RECOMPILE);
------

-- This helps you find the most expensive cached stored procedures from a memory perspective
-- You should look at this if you see signs of memory pressure

(63)

-- Top Cached SPs By Total Physical Reads. Physical reads relate to disk read I/O pressure  (Query 63) (SP Physical Reads)
SELECT TOP(25) p.name AS [SP Name],qs.total_physical_reads AS [TotalPhysicalReads], 
qs.total_physical_reads/qs.execution_count AS [AvgPhysicalReads], qs.execution_count, 
qs.total_logical_reads,qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],
CASE WHEN CONVERT(nvarchar(max), qp.query_plan) LIKE N'%<MissingIndexes>%' THEN 1 ELSE 0 END AS [Has Missing Index],
FORMAT(qs.last_execution_time, 'yyyy-MM-dd HH:mm:ss', 'en-US') AS [Last Execution Time], 
FORMAT(qs.cached_time, 'yyyy-MM-dd HH:mm:ss', 'en-US') AS [Plan Cached Time]
-- ,qp.query_plan AS [Query Plan] -- Uncomment if you want the Query Plan 
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) AS qp
WHERE qs.database_id = DB_ID()
AND qs.total_physical_reads > 0
ORDER BY qs.total_physical_reads DESC, qs.total_logical_reads DESC OPTION (RECOMPILE);
------

-- This helps you find the most expensive cached stored procedures from a read I/O perspective
-- You should look at this if you see signs of I/O pressure or of memory pressure

(64)

-- Top Cached SPs By Total Logical Writes (Query 64) (SP Logical Writes)
-- Logical writes relate to both memory and disk I/O pressure 
SELECT TOP(25) p.name AS [SP Name], qs.total_logical_writes AS [TotalLogicalWrites], 
qs.total_logical_writes/qs.execution_count AS [AvgLogicalWrites], qs.execution_count,
ISNULL(qs.execution_count/DATEDIFF(Minute, qs.cached_time, GETDATE()), 0) AS [Calls/Minute],
qs.total_elapsed_time, qs.total_elapsed_time/qs.execution_count AS [avg_elapsed_time],
CASE WHEN CONVERT(nvarchar(max), qp.query_plan) LIKE N'%<MissingIndexes>%' THEN 1 ELSE 0 END AS [Has Missing Index], 
FORMAT(qs.last_execution_time, 'yyyy-MM-dd HH:mm:ss', 'en-US') AS [Last Execution Time], 
FORMAT(qs.cached_time, 'yyyy-MM-dd HH:mm:ss', 'en-US') AS [Plan Cached Time]
-- ,qp.query_plan AS [Query Plan] -- Uncomment if you want the Query Plan 
FROM sys.procedures AS p WITH (NOLOCK)
INNER JOIN sys.dm_exec_procedure_stats AS qs WITH (NOLOCK)
ON p.[object_id] = qs.[object_id]
CROSS APPLY sys.dm_exec_query_plan(qs.plan_handle) AS qp
WHERE qs.database_id = DB_ID()
AND qs.total_logical_writes > 0
AND DATEDIFF(Minute, qs.cached_time, GETDATE()) > 0
ORDER BY qs.total_logical_writes DESC OPTION (RECOMPILE);
------

-- This helps you find the most expensive cached stored procedures from a write I/O perspective
-- You should look at this if you see signs of I/O pressure or of memory pressure

PS 这不是一个详尽的答案

Answer 2

有人可以直接给出一个好的/正确的解释。

我首先会说任务管理器不是衡量 SQL Server 内存消耗的正确位置，当 SQL Server 服务帐户具有内存中的锁定页面（LPIM）特权时，它不会告诉您正确的值。这是因为通常任务管理器会跟踪Process Private bytes哪些可分页内存并通过VirtualAlloc()函数分配，但具有 LPIM 内存分配的服务帐户是由不可分页的AWE API完成的，因此任务管理器不会跟踪它，这可能导致不正确价值。

SQL Server 使用分配给它的内存是很正常的，这通常看起来像是在使用高内存，但这很正常。如果某些工具显示 CPU 利用率低并且任务管理器显示高内存，请不要惊慌，这可能是正常的。要了解 SQL Server 使用了多少物理内存，请使用以下查询

select
(physical_memory_in_use_kb/1024)Phy_Memory_usedby_Sqlserver_MB,
(locked_page_allocations_kb/1024 )Locked_pages_used_Sqlserver_MB,
(virtual_address_space_committed_kb/1024 )Total_Memory_UsedBySQLServer_MB,
process_physical_memory_low,
process_virtual_memory_low
from sys. dm_os_process_memory

Phy_Memory_usedby_Sqlserver_MB -- 以 MB为单位提供SQL Server 使用的总物理内存Total_Memory_usedBy_SQLServer_MB- -以 MB为单位提供SQL Server 使用的 总内存（RAM+页面文件）

要了解有关为什么不应使用任务管理器的更多信息，请参阅锁定页面的乐趣、AWE、任务管理器和工作集……