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sys.dm_os_memory_objects (Transact-SQL)

 

Updated: July 24, 2015

Applies To: SQL Server 2014, SQL Server 2016 Preview

Returns memory objects that are currently allocated by SQL Server. You can use sys.dm_os_memory_objects to analyze memory use and to identify possible memory leaks.

Applies to: SQL Server (SQL Server 2008 through current version), SQL Database V12.


Column name

Data type

Description

memory_object_address

varbinary(8)

Address of the memory object. Is not nullable.

parent_address

varbinary(8)

Address of the parent memory object. Is nullable.

pages_allocated_count

int

Number of pages that are allocated by this object. Is not nullable.

Applies to: SQL Server 2008 through SQL Server 2008 R2.

pages_in_bytes

bigint

Amount of memory in bytes that is allocated by this instance of the memory object. Is not nullable.

Applies to: SQL Server 2012 through SQL Server 2016.

creation_options

int

Internal use only. Is nullable.

bytes_used

bigint

Internal use only. Is nullable.

type

nvarchar(60)

Type of memory object.

This indicates some component that this memory object belongs to, or the function of the memory object. Is nullable.

name

varchar(128)

Internal use only. Nullable.

memory_node_id

smallint

ID of a memory node that is being used by this memory object. Is not nullable.

creation_time

datetime

Internal use only. Is nullable.

max_pages_allocated_count

int

Maximum number of pages allocated by this memory object. Is not nullable.

Applies to: SQL Server 2008 through SQL Server 2008 R2.

page_size_in_bytes

int

Size of pages in bytes allocated by this object. Is not nullable.

Applies to: SQL Server 2012 through SQL Server 2016.

max_pages_in_bytes

bigint

Maximum amount of memory ever used by this memory object. Is not nullable.

page_allocator_address

varbinary(8)

Memory address of page allocator. Is not nullable. For more information, see sys.dm_os_memory_clerks (Transact-SQL).

creation_stack_address

varbinary(8)

Internal use only. Is nullable.

sequence_num

int

Internal use only. Is nullable.

partition_type

int

The type of partition:

  • 0 - Non-partitionable memory object

  • 1 - Partitionable memory object, currently not partitioned

  • 2 - Partitionable memory object, partitioned by NUMA node. In an environment with a single NUMA node this is equivalent to 1.

  • 3 - Partitionable memory object, partitioned by CPU.

contention_factor

real

A value specifying contention on this memory object, with 0 meaning no contention. The value is updated whenever a specified number of memory allocations were made reflecting contention during that period. Applies only to thread-safe memory objects.

waiting_tasks_count

bigint

Number of waits on this memory object. This counter is incremented whenever memory is allocated from this memory object. The increment is the number of tasks currently waiting for access to this memory object. Applies only to thread-safe memory objects. This is a best effort value without a correctness guarantee.

exclusive_access_count

bigint

Specifies how often this memory object was accessed exclusively. Applies only to thread-safe memory objects. This is a best effort value without a correctness guarantee.

partition_type, contention_factor, waiting_tasks_count, and exclusive_access_count are not yet implemented in SQL Database V12.

Requires VIEW SERVER STATE permission on the server.

Memory objects are heaps. They provide allocations that have a finer granularity than those provided by memory clerks. SQL Server components use memory objects instead of memory clerks. Memory objects use the page allocator interface of the memory clerk to allocate pages. Memory objects do not use virtual or shared memory interfaces. Depending on the allocation patterns, components can create different types of memory objects to allocate regions of arbitrary size.

The typical page size for a memory object is 8 KB. However, incremental memory objects can have page sizes that range from 512 bytes to 8 KB.

System_CAPS_noteNote

Page size is not a maximum allocation. Instead, page size is allocation granularity that is supported by a page allocator and that is implemented by a memory clerk. You can request allocations greater than 8 KB from memory objects.

The following example returns the amount of memory allocated by each memory object type.

SELECT SUM (pages_in_bytes) as 'Bytes Used', type 
FROM sys.dm_os_memory_objects
GROUP BY type 
ORDER BY 'Bytes Used' DESC;
GO
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