Applies to: SQL Server (all supported versions) Azure SQL Database
Returns detailed information about missing indexes, excluding spatial indexes.
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.
|Column name||Data type||Description|
|index_handle||int||Identifies a particular missing index. The identifier is unique across the server.
|database_id||smallint||Identifies the database where the table with the missing index resides.|
|object_id||int||Identifies the table where the index is missing.|
|equality_columns||nvarchar(4000)||Comma-separated list of columns that contribute to equality predicates of the form:
|inequality_columns||nvarchar(4000)||Comma-separated list of columns that contribute to inequality predicates, for example, predicates of the form:
table.column > constant_value
Any comparison operator other than "=" expresses inequality.
|included_columns||nvarchar(4000)||Comma-separated list of columns needed as covering columns for the query. For more information about covering or included columns, see Create Indexes with Included Columns.
For memory-optimized indexes (both hash and memory-optimized nonclustered), ignore
|statement||nvarchar(4000)||Name of the table where the index is missing.|
Information returned by
sys.dm_db_missing_index_details is updated when a query is optimized by the query optimizer, and is not persisted. Missing index information is kept only until the database engine is restarted. Database administrators should periodically make backup copies of the missing index information if they want to keep it after server recycling. Use the
sqlserver_start_time column in sys.dm_os_sys_info to find the last database engine startup time.
To determine which missing index groups a particular missing index is part of, you can query the
sys.dm_db_missing_index_groups dynamic management view by equijoining it with
sys.dm_db_missing_index_details based on the
The result set for this DMV is limited to 600 rows. Each row contains one missing index. If you have more than 600 missing indexes, you should address the existing missing indexes so you can then view the newer ones.
Using Missing Index Information in CREATE INDEX Statements
To convert the information returned by
sys.dm_db_missing_index_details into a CREATE INDEX statement for both memory-optimized and disk-based indexes, equality columns should be put before the inequality columns, and together they should make the key of the index. Included columns should be added to the CREATE INDEX statement using the INCLUDE clause. To determine an effective order for the equality columns, order them based on their selectivity: list the most selective columns first (leftmost in the column list).
For more information about memory-optimized indexes, see Indexes for Memory-Optimized Tables.
If a transaction creates or drops a table, the rows containing missing index information about the dropped objects are removed from this dynamic management object, preserving transaction consistency.
On SQL Server, requires
VIEW SERVER STATE permission.
On SQL Database Basic, S0, and S1 service objectives, and for databases in elastic pools, the server admin account or the Azure Active Directory admin account is required. On all other SQL Database service objectives, the
VIEW DATABASE STATE permission is required in the database.