By: Greg Robidoux
Overview
With the introduction of SQL Server 2005, Microsoft introduced Dynamic Management Views (DMVs) which allow you to get better insight into what is happening in SQL Server. Without these new tools a lot of the information was unavailable or very difficult to obtain.
DMVs are a great tool to help troubleshoot performance related issues and once you understand their power they will become a staple for your Database Administration.
Explanation
The DMVs were introduced in SQL 2005 and with each new release, Microsoft has been adding additional DMVs to help troubleshoot issues. DMVs actually come in two flavors DMVs (dynamic management views) and DMFs (dynamic management functions) and are sometimes classified as DMOs (dynamic management objects). The DMVs act just like any other view where you can select data from them and the DMFs require values to be passed to the function just like any other function.
The DMVs are broken down into the following categories:
- Change Data Capture Related Dynamic Management Views
- Change Tracking Related Dynamic Management Views
- Common Language Runtime Related Dynamic Management Views
- Database Mirroring Related Dynamic Management Views
- Database Related Dynamic Management Views
- Execution Related Dynamic Management Views and Functions
- Extended Events Dynamic Management Views
- Full-Text Search Related Dynamic Management Views
- Filestream-Related Dynamic Management Views (Transact-SQL)
- I/O Related Dynamic Management Views and Functions
- Index Related Dynamic Management Views and Functions
- Object Related Dynamic Management Views and Functions
- Query Notifications Related Dynamic Management Views
- Replication Related Dynamic Management Views
- Resource Governor Dynamic Management Views
- Service Broker Related Dynamic Management Views
- SQL Server Operating System Related Dynamic Management Views
- Transaction Related Dynamic Management Views and Functions
- Security Related Dynamic Management Views
Here are some of the more useful DMVs that you should familiarize yourself with:
- sys.dm_exec_cached_plans - Cached query plans available to SQL Server
- sys.dm_exec_sessions - Sessions in SQL Server
- sys.dm_exec_connections - Connections to SQL Server
- sys.dm_db_index_usage_stats - Seeks, scans, lookups per index
- sys.dm_io_virtual_file_stats - IO statistics for databases and log files
- sys.dm_tran_active_transactions - Transaction state for an instance of SQL Server
- sys.dm_exec_sql_text - Returns TSQL code
- sys.dm_exec_query_plan - Returns query plan
- sys.dm_os_wait_stats - Returns information what resources SQL is waiting on
- sys.dm_os_performance_counters - Returns performance monitor counters related to SQL Server
Additional Information
Here are some additional articles about DMVs.
- Dynamic Management Views and Functions in SQL Server 2005
- Understanding Catalog Views in SQL Server 2005 and 2008
- Additional DMV tips
