sys.dm_os_memory_objects (Transact-SQL)

 

Updated: July 24, 2015

THIS TOPIC APPLIES TO: yesSQL Server (starting with 2008)yesAzure SQL DatabaseyesAzure SQL Data Warehouse yesParallel Data Warehouse

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.

Column nameData typeDescription
memory_object_addressvarbinary(8)Address of the memory object. Is not nullable.
parent_addressvarbinary(8)Address of the parent memory object. Is nullable.
pages_allocated_countintApplies to: SQL Server 2008 through SQL Server 2008 R2.

Number of pages that are allocated by this object. Is not nullable.
pages_in_bytesbigintApplies to: SQL Server 2012 through SQL Server 2016.

Amount of memory in bytes that is allocated by this instance of the memory object. Is not nullable.
creation_optionsintInternal use only. Is nullable.
bytes_usedbigintInternal use only. Is nullable.
typenvarchar(60)Type of memory object.

This indicates some component that this memory object belongs to, or the function of the memory object. Is nullable.
namevarchar(128)Internal use only. Nullable.
memory_node_idsmallintID of a memory node that is being used by this memory object. Is not nullable.
creation_timedatetimeInternal use only. Is nullable.
max_pages_allocated_countintApplies to: SQL Server 2008 through SQL Server 2008 R2.

Maximum number of pages allocated by this memory object. Is not nullable.
page_size_in_bytesintApplies to: SQL Server 2012 through SQL Server 2016.

Size of pages in bytes allocated by this object. Is not nullable.
max_pages_in_bytesbigintMaximum amount of memory ever used by this memory object. Is not nullable.
page_allocator_addressvarbinary(8)Memory address of page allocator. Is not nullable. For more information, see sys.dm_os_memory_clerks (Transact-SQL).
creation_stack_addressvarbinary(8)Internal use only. Is nullable.
sequence_numintInternal use only. Is nullable.
partition_typeintThe 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_factorrealA 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_countbigintNumber 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_countbigintSpecifies 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.
pdw_node_idintApplies to: Azure SQL Data Warehouse, Parallel Data Warehouse

The identifier for the node that this distribution is on.

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_ICON_note.jpg Note


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  

Dynamic Management Views and Functions (Transact-SQL)
SQL Server Operating System Related Dynamic Management Views (Transact-SQL)
sys.dm_os_memory_clerks (Transact-SQL)

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