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This is a view in the mssqlsystemresource database.
Returns detailed information about missing indexes, excluding spatial indexes. 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 SQL Server is restarted. Database administrators should periodically make backup copies of the missing index information if they want to keep it after server recycling. 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 index_handle column.
To convert the information returned by sys.dm_db_missing_index_details into a CREATE INDEX statement, 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).
| Column name |
Data type |
Description |
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index_handle
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int
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Identifies a particular missing index. The identifier is unique across the server. index_handle is the key of this table.
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database_id
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smallint
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Identifies the database where the table with the missing index resides.
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object_id
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int
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Identifies the table where the index is missing.
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equality_columns
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nvarchar(4000)
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Comma-separated list of columns that contribute to equality predicates of the form:
table.column = constant_value
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inequality_columns
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nvarchar(4000)
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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.
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included_columns
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nvarchar(4000)
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Comma-separated list of columns needed as covering columns for the query.
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statement
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nvarchar(4000)
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Name of the table where the index is missing.
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Statement to see the most needed query
| SELECT statement AS [database.scheme.table], column_id , column_name, column_usage, migs.user_seeks, migs.user_scans, migs.last_user_seek, migs.avg_total_user_cost, migs.avg_user_impact FROM sys.dm_db_missing_index_details AS mid CROSS APPLY sys.dm_db_missing_index_columns (mid.index_handle) INNER JOIN sys.dm_db_missing_index_groups AS mig ON mig.index_handle = mid.index_handle INNER JOIN sys.dm_db_missing_index_group_stats AS migs ON mig.index_group_handle=migs.group_handle ORDER BY mig.index_group_handle, mig.index_handle, column_id GO |
See also Create all your missing indexes for a generation of statements of the missing indexes
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