Returns a row for each query plan that is cached by SQL Server for faster query execution. You can use this dynamic management view to find cached query plans, cached query text, the amount of memory taken by cached plans, and the reuse count of the cached plans.
In Azure SQL Database, dynamic management views cannot expose information that would impact database containment or expose information about other databases the user has access to. To avoid exposing this information, every row that contains data that doesn’t belong to the connected tenant is filtered out. In addition, the values in the columns memory_object_address and pool_id are filtered; the column value is set to NULL.
|Column name||Data type||Description|
|bucketid||int||ID of the hash bucket in which the entry is cached. The value indicates a range from 0 through the hash table size for the type of cache.|
For the SQL Plans and Object Plans caches, the hash table size can be up to 10007 on 32-bit systems and up to 40009 on 64-bit systems. For the Bound Trees cache, the hash table size can be up to 1009 on 32-bit systems and up to 4001 on 64-bit systems. For the Extended Stored Procedures cache the hash table size can be up to 127 on 32-bit and 64-bit systems.
|refcounts||int||Number of cache objects that are referencing this cache object. Refcounts must be at least 1 for an entry to be in the cache.|
|usecounts||int||Number of times the cache object has been looked up. Not incremented when parameterized queries find a plan in the cache. Can be incremented multiple times when using showplan.|
|size_in_bytes||int||Number of bytes consumed by the cache object.|
|memory_object_address||varbinary(8)||Memory address of the cached entry. This value can be used with sys.dm_os_memory_objects to get the memory breakdown of the cached plan and with sys.dm_os_memory_cache_entries_entries to obtain the cost of caching the entry.|
|cacheobjtype||nvarchar(34)||Type of object in the cache. The value can be one of the following:|
Compiled Plan Stub
CLR Compiled Func
CLR Compiled Proc
|objtype||nvarchar(16)||Type of object. Below are the possible values and their corresponding descriptions.|
Proc: Stored procedure
Prepared: Prepared statement
Adhoc: Ad hoc query. Refers to Transact-SQL submitted as language events by using osql or sqlcmd instead of as remote procedure calls.
UsrTab: User table
SysTab: System table
Check: CHECK constraint
|plan_handle||varbinary(64)||Identifier for the in-memory plan. This identifier is transient and remains constant only while the plan remains in the cache. This value may be used with the following dynamic management functions:|
|pool_id||int||The ID of the resource pool against which this plan memory usage is accounted for.|
|pdw_node_id||int||Applies to: Azure SQL Data Warehouse, Parallel Data Warehouse|
The identifier for the node that this distribution is on.
On SQL Server requires VIEW SERVER STATE permission on the server.
On SQL Database Premium Tiers requires the VIEW DATABASE STATE permission in the database. On SQL Database Standard and Basic Tiers requires the SQL Database admin account.
The following example returns the SQL text of all cached entries that have been used more than once.
SELECT usecounts, cacheobjtype, objtype, text FROM sys.dm_exec_cached_plans CROSS APPLY sys.dm_exec_sql_text(plan_handle) WHERE usecounts > 1 ORDER BY usecounts DESC; GO
The following example returns the query plans of all cached triggers.
SELECT plan_handle, query_plan, objtype FROM sys.dm_exec_cached_plans CROSS APPLY sys.dm_exec_query_plan(plan_handle) WHERE objtype ='Trigger'; GO
The following example returns the SET options with which the plan was compiled. The
handle for the plan is also returned. The PIVOT operator is used to output the
handle attributes as columns rather than as rows. For more information about the value returned in
options, see sys.dm_exec_plan_attributes (Transact-SQL).
SELECT plan_handle, pvt.set_options, pvt.sql_handle FROM ( SELECT plan_handle, epa.attribute, epa.value FROM sys.dm_exec_cached_plans OUTER APPLY sys.dm_exec_plan_attributes(plan_handle) AS epa WHERE cacheobjtype = 'Compiled Plan' ) AS ecpa PIVOT (MAX(ecpa.value) FOR ecpa.attribute IN ("set_options", "sql_handle")) AS pvt; GO
The following example returns a breakdown of the memory used by all compiled plans in the cache.
SELECT plan_handle, ecp.memory_object_address AS CompiledPlan_MemoryObject, omo.memory_object_address, pages_allocated_count, type, page_size_in_bytes FROM sys.dm_exec_cached_plans AS ecp JOIN sys.dm_os_memory_objects AS omo ON ecp.memory_object_address = omo.memory_object_address OR ecp.memory_object_address = omo.parent_address WHERE cacheobjtype = 'Compiled Plan'; GO
Dynamic Management Views and Functions (Transact-SQL)
Execution Related Dynamic Management Views and Functions (Transact-SQL)