Short Introduction:Dynamic management views and functions return information that can be used to monitor the health of a server instance, diagnose problems, and tune performance

I have found the following 8 DMV and DMF very useful

Database Related:•sys.dm_db_file_space_usage•sys.dm_db_session_space_usage•sys.dm_db_partition_statsExecution Related:•sys.dm_exec_query_stats•sys.dm_exec_sql_text

Index Related:•sys.dm_db_index_operational_stats •sys.dm_db_index_physical_stats •sys.dm_db_missing_index_columns

sys.dm_db_file_space_usage Returns space usage information for each file in database tempdb (not available for other databases ). This DMV is specially useful if tempdb utilization is highExample: display tempdb files, sizes and page counts

select M.physical_name, M.size, U.unallocated_extent_page_count, U.user_object_reserved_page_count, U.internal_object_reserved_page_count, U.mixed_extent_page_countfrom sys.dm_db_file_space_usage U join sys.master_files as M on M.database_id = U.database_id and M.file_id = U.file_id

sys.dm_db_file_space_usage Example 2: returns the amount of free space in tempdb

SELECT free_pages = SUM(unallocated_extent_page_count),Free_space_in_MB = (SUM(unallocated_extent_page_count)/128.) sys.dm_db_file_space_usage

sys.dm_db_session_space_usage

# of pages used by each SPID tempdb. You can use this DMV to find the session filling up tempdb.Example: top five tasks consuming most tempdb space

select top 5 session_id, user_objects_alloc_page_count * 8 / 1024.0 [Allocated space in MB]from sys.dm_db_session_space_usage ORDER BY (user_objects_alloc_page_count +internal_objects_alloc_page_count) DESC

sys.dm_db_partition_stats returns space utilization within a database. I found this DMV very helpful to compute and report space used by db objectsExample: determines space used by objects

select convert(char(30), object_name(object_id)),

sum(in_row_reserved_page_count)/128.,

sum(lob_reserved_page_count)/128.from sys.dm_db_partition_stats group by object_id order by sum(in_row_reserved_page_count) desc

sys.dm_exec_query_statsReturns aggregate statistics for cached query plans. This DMV contains 1 row/query within cached plans.

** When a plan is removed from the cache, the corresponding rows are removed from this view.

I have some examples on the next slides:

sys.dm_exec_query_stats …CONTINUED-- Cached SP's By Execution CountSELECT TOP (25) sp_name = qt.text ,db_name = db_name(qt.dbid),qs.execution_count AS 'Exec. Count', Cpu = qs.total_worker_timeqs.max_logical_reads, qs.max_logical_writes, qs.total_physical_readsFROM sys.dm_exec_query_stats AS qsCROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qtORDER BY qs.execution_count DESC;

sys.dm_exec_query_stats … CONTINUED-- Cached SP's By Logical ReadsSELECT TOP (25) sp_name = qt.text, db_name = db_name(qt.dbid),total_logical_reads, qs.total_worker_time,qs.total_logical_writes, qs.total_physical_readsqs.max_logical_reads, qs.max_logical_writes FROM sys.dm_exec_query_stats AS qsCROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS qtORDER BY total_logical_reads DESC;

•sys. dm_exec_sql_text( sql handle |plan_handle) *table valued function used along with other DMVs to identify the sql text specified by the sql handleExample the below query returns the SQL statement and average CPU time for the top five queries.

SELECT TOP 5 avg_cpu = total_worker_time/execution_count, Statement_text = st.text, FROM sys.dm_exec_query_stats AS qs CROSS APPLY sys.dm_exec_sql_text(qs.sql_handle) AS st ORDER BY total_worker_time/execution_count DESC

sys.dm_db_index_operational_stats Provides useful stats on how many times an index has been used, locked, waited on, etc. Example on the next slide…

The below query provides information on reads/writes to a table

select objectname=object_name(s.object_id), indexname=i.name, i.index_id,reads=range_scan_count+singleton_lookup_count, writes = leaf_insert_count+leaf_update_count+ leaf_delete_count , nonleaf_insert_count + nonleaf_update_count + nonleaf_delete_count leaf_page_splits = leaf_allocation_countfrom sys.dm_db_index_operational_stats (NULL,NULL,NULL,NULL) s,sys.indexes I where objectproperty(s.object_id,'IsUserTable') = 1and i.object_id = s.object_id and i.index_id = s.index_id

sys.dm_db_index_physical_stats

Found this query invaluable to fetch size and fragmentation information for the data and indexes of the specified table.Example:

select object_name(object_id) , avg_fragmentation_in_percent from sys.dm_db_index_physical_stats(null,null,null,null,null)where database_id = db_id('DBA_rep')and index_id in ( 0,1)

sys.dm_db_index_usage_stats Returns query optimizer use of an index in a plan.  •Usage information is re-recorded each time the plan is executed.  • This DMV provides the following information: User seeks i.e. the number of times a query was used to find a single rowUser scans i.e. A range of values, or to resolve a non-unique query User_lookups if it has been used to resolve a bookmark lookup and User updates or how many changes were made to the index

sys.dm_db_missing_index_columns Returns information about database table columns that are missing an index, excluding spatial indexes.

the the EndEnd