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sys.dm_os_memory_clerks (Transact-SQL)

Returns the set of all memory clerks that are currently active in the instance of SQL Server. 

Column name

Data type

Description

memory_clerk_address

varbinary(8)

Specifies the unique memory address of the memory clerk. This is the primary key column. Is not nullable.

type

nvarchar(60)

Specifies the type of memory clerk. Every clerk has a specific type, such as CLR Clerks MEMORYCLERK_SQLCLR. Is not nullable.

name

nvarchar(256)

Specifies the internally assigned name of this memory clerk. A component can have several memory clerks of a specific type. A component might choose to use specific names to identify memory clerks of the same type. Is not nullable.

memory_node_id

smallint

Specifies the ID of the memory node. Not nullable.

pages_kb

bigint

Specifies the amount of page memory allocated in kilobytes (KB) for this memory clerk. Is not nullable.

virtual_memory_reserved_kb

bigint

Specifies the amount of virtual memory that is reserved by a memory clerk. Is not nullable.

virtual_memory_committed_kb

bigint

Specifies the amount of virtual memory that is committed by a memory clerk. The amount of committed memory should always be less than the amount of reserved memory. Is not nullable.

awe_allocated_kb

bigint

Specifies the amount of memory in kilobytes (KB) locked in the physical memory and not paged out by the operating system. Is not nullable.

shared_memory_reserved_kb

bigint

Specifies the amount of shared memory that is reserved by a memory clerk. The amount of memory reserved for use by shared memory and file mapping. Is not nullable.

shared_memory_committed_kb

bigint

Specifies the amount of shared memory that is committed by the memory clerk. Is not nullable.

page_size_in_bytes

bigint

Specifies the granularity of the page allocation for this memory clerk. Is not nullable.

page_allocator_address

varbinary(8)

Specifies the address of the page allocator. This address is unique for a memory clerk and can be used in sys.dm_os_memory_objects to locate memory objects that are bound to this clerk. Is not nullable.

host_address

varbinary(8)

Specifies the memory address of the host for this memory clerk. For more information, see sys.dm_os_hosts (Transact-SQL). Components, such as Microsoft SQL Server Native Client, access SQL Server memory resources through the host interface.

0x00000000 = Memory clerk belongs to SQL Server.

Is not nullable.

Requires VIEW SERVER STATE permission on the server.

The SQL Server memory manager consists of a three-layer hierarchy. At the bottom of the hierarchy are memory nodes. The middle level consists of memory clerks, memory caches, and memory pools. The top layer consists of memory objects. These objects are generally used to allocate memory in an instance of SQL Server.

Memory nodes provide the interface and the implementation for low-level allocators. Inside SQL Server, only memory clerks have access to memory nodes. Memory clerks access memory node interfaces to allocate memory. Memory nodes also track the memory allocated by using the clerk for diagnostics. Every component that allocates a significant amount of memory must create its own memory clerk and allocate all its memory by using the clerk interfaces. Frequently, components create their corresponding clerks at the time SQL Server is started.

In SQL Server 2012, the following columns have been renamed.

Previous Column Name

New Column Name

single_pages_kb

pages_kb

In SQL Server 2012, the column multi_pages_kb has been removed.

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