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Index Properties F1 Help

The sections in this topic refer to various index properties that are available by using SQL Server Management Studio dialogs.

In This Topic:

Index Properties General Page

Select (Index) Columns Dialog Box

Index Properties Storage Page

Index Properties Spatial Page

Index Properties Filter Page

Use the General page to view or modify index properties for the selected table or view. The options for each page may change based on the type of index selected.

Table name

Displays the name of the table or view that the index was created on. This field is read-only. To select a different table, close the Index Properties page, select the correct table, and then open the Index Properties page again.

Spatial indexes cannot be specified on indexed views. Spatial indexes can be defined only for a table that has a primary key. The maximum number of primary key columns on the table is 15. The combined per-row size of the primary-key columns is limited to a maximum of 895 bytes.

Index name

Displays the name of the index. This field is read-only for an existing index. When creating a new index, type the name of the index.

Index type

Indicates the type of index. For new indexes, indicates the type of index selected when opening the dialog box. Indexes can be: Clustered, Nonclustered, Primary XML, Secondary XML, Spatial, Clustered columnstore, or Nonclustered Columnstore.

Note   Only one clustered index is allowed for each table. Only one xVelocity memory optimized columnstore index is allowed for each table.

Unique

Selecting this check box makes the index unique. No two rows are permitted to have the same index value. By default, this check box is cleared. When modifying an existing index, index creation will fail if two rows have the same value. For columns where NULL is permitted, a unique index permits one NULL value.

If you select Spatial in the Index type field, the Unique check box is dimmed.

Index key columns

Add the desired columns to the Index key columns grid. When more than one column is added, the columns must be listed in the order desired. The column order in an index can have a great impact on the index performance.

No more than 16 columns can participate in a single composite index. For greater than 16 columns, see included columns at the end of this topic.

A spatial index can be defined only on a single column that contains a spatial data type (a spatial column).

Name

Displays the name of the column that participates in the index key.

Sort Order

Specifies the sort direction of the selected index column, either Ascending or Descending.

Note Note

If the index type is Primary XML or Spatial, this column does not appear in the table.

Data Type

Displays the data type information.

Note Note

If the table column is a computed column, Data type displays "computed column."

Size

Displays the maximum number of bytes required to store the column data type. Displays zero (0) for a spatial or XML column.

Identity

Displays whether the column participating in the index key is an identity column.

Allow NULLs

Displays whether the column participating in the index key allows NULL values to be stored in the table or view column.

Add

Adds a column to the index key. Select table columns from the Select Columns from <table name> dialog box that appears when you click Add. For a spatial index, after you select one column, this button is dimmed.

Remove

Removes the selected column from participation in the index key.

Move Up

Moves the selected column up in the index key grid.

Move Down

Moves the selected column down in the index key grid.

Columnstore columns

Click Add to select columns for the columnstore index. For limitations on a columnstore index, see CREATE COLUMNSTORE INDEX (Transact-SQL).

Included columns

Include nonkey columns in the nonclustered index. This option allows you to bypass the current index limits on the total size of an index key and the maximum number of columns participating in an index key by adding columns as nonkey columns in the leaf level of the nonclustered index. For more information, see Create Indexes with Included Columns

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Use this page to add columns to the Index Properties General page when creating or modifying an index.

Check box

Select to add columns.

Name

Name of the column.

Data Type

The data type of the column.

Bytes

The size of the column in bytes.

Identity

Displays Yes for identity columns, and No when the column is not an identity column.

Allow Nulls

Displays Yes when the table definition allows null values for the column. Displays No when the table definition does not allow nulls for the column.

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Use this page to view or modify filegroup or partition scheme properties for the selected index. Only shows options related to the type of index.

Filegroup

Stores the index in the specified filegroup. The list only displays standard (row) filegroups. The default list selection is the PRIMARY filegroup of the database. For more information, see Database Files and Filegroups.

Filestream filegroup

Specifies the filegroup for FILESTREAM data. This list displays only FILESTREAM filegroups. The default list selection is the PRIMARY FILESTREAM filegroup. For more information, see FILESTREAM (SQL Server).

Partition scheme

Stores the index in a partition scheme. Clicking Partition Scheme enables the grid below. The default list selection is the partition scheme that is used for storing the table data. When you select a different partition scheme in the list, the information in the grid is updated. For more information, see Partitioned Tables and Indexes.

The partition scheme option is unavailable if there are no partition schemes in the database.

Filestream partition scheme

Specifies the partition scheme for FILESTREAM data. The partition scheme must be symmetric with the scheme that is specified in the Partition scheme option.

If the table is not partitioned, the field is blank.

Partition Scheme Parameter

Displays the name of the column that participates in the partition scheme.

Table Column

Select the table or view to map to the partition scheme.

Column Data Type

Displays data type information about the column.

Note Note

If the table column is a computed column, Column Data Type displays "computed column."

Allow online processing of DML statements while moving the index

Allows users to access the underlying table or clustered index data and any associated nonclustered indexes during the index operation. For more information, see Perform Index Operations Online.

Note Note

This option is not available for XML indexes, or if the index is a disabled clustered index.

Set maximum degree of parallelism

Limits the number of processors to use during parallel plan execution. The default value, 0, uses the actual number of available CPUs. Setting the value to 1 suppresses parallel plan generation; setting the value to a number greater than 1 restricts the maximum number of processors used by a single query execution. This option only becomes available if the dialog box is in the Rebuild or Recreate state. For more information, see Set the Max Degree of Parallelism Option for Optimal Performance.

Note Note

If a value greater than the number of available CPUs is specified, the actual number of available CPUs is used.

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Use the Spatial page to view or specify the values of the spatial properties. For more information, see Spatial Data (SQL Server).

Bounding Box

The bounding box is the perimeter of the top-level grid of a geometric plane. The bounding-box parameters exist only in the geometry grid tessellation. These parameters are unavailable if the Tessellation Scheme is Geography grid.

The panel displays the (X-min,Y-min) and (X-max,Y-max) coordinates of the bounding box. There are no default coordinate values. Therefore, when you are creating a new spatial index on a geometry type column, you must specify the coordinate values.

X-min

The X-coordinate of the lower-left corner of the bounding box.

Y-min

The Y-coordinate of the lower-left corner of the bounding box.

X-max

The X-coordinate of the upper-right corner of the bounding box.

Y-max

The Y-coordinate of upper-right corner of the bounding box.

General

Tessellation Scheme

Indicates the tessellation scheme of the index. The supported tessellation schemes are as follows.

Geometry grid

Specifies the geometry grid tessellation scheme, which applies to a column of the geometry data type.

Geometry Auto grid

This option is enabled for SQL Server when database compatibility level is set to 110 or higher.

Geography grid

Specifies the geography grid tessellation scheme, which applies to a column of the geography data type.

Geography Auto grid

This option is enabled for SQL Server when database compatibility level is set to 110 or higher.

For information about how SQL Server implements tessellation, see Spatial Data (SQL Server).

Cells Per Object

Indicates the number of tessellation cells-per-object that can be used for a single spatial object in the index. This number can be any integer between 1 and 8192, inclusive. The default is 16, and 8 for earlier versions of SQL Server when database compatibility level is set to 110 or higher.

At the top level, if an object covers more cells than specified by n, the indexing uses as many cells as necessary to provide a complete top-level tessellation. In such cases, an object might receive more than the specified number of cells. In this case, the maximum number is the number of cells generated by the top-level grid, which depends on the Level 1 density.

Grids

This panel shows the density of the grid at each level of the tessellation scheme. Density is specified as Low, Medium, or High. The default is Medium. Low represents a 4x4 grid (16 cells), Medium represents an 8x8 grid (64 cells), and High represents a 16x16 grid (256 cells). These options are not available when the Geometry Auto grid or Geography Auto grid tessellation options are chosen.

Level 1

The density of the first-level (top) grid.

Level 2

The density of the second-level grid.

Level 3

The density of the third-level grid.

Level 4

The density of the fourth-level grid.

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Use this page to enter the filter predicate for a filtered index. For more information, see Create Filtered Indexes.

Filter Expression

Defines which data rows to include in the filtered index. For example, StartDate > '20000101' AND EndDate IS NOT NULL'.

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