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Spatial Indexes Dialog Box (Visual Database Tools)

Use the Spatial Indexes dialog box to create indexes for columns of the geometry or geography data type (spatial columns), which cannot be indexed using the Index/Keys dialog box. Each spatial column can have more than one spatial Index, but they must be created one at a time.

For information about restrictions on spatial index creation, see Restrictions on Spatial Indexes.

Options

  • Selected Spatial Index
    Lists existing spatial indexes. Select to show its properties in the grid to the right. If the list is empty, no spatial indexes have been defined for the table.

  • Add
    Create a new spatial index.

  • Delete
    Delete the spatial index selected in the Selected Spatial Index list.

  • 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.

    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.

  • Columns
    Indicates the column name and sort order.

  • IsSpatialIndex
    Indicates that a spatial index is selected.

  • 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.

  • Tessellation Scheme
    The tessellation scheme, either Geometry grid for a geometry column or Geography grid for a geography column.

  • Type
    Indicates that a spatial index is selected.

  • X-max
    Specifies the x-coordinate of the upper-right corner of the bounding box. This property is dimmed if the Tessellation Scheme is Geography grid.

  • X-min
    Specifies the x-coordinate of the lower-left corner of the bounding box. This property is dimmed if the Tessellation Scheme is Geography grid.

  • Y-max
    Specifies the y-coordinate of upper-right corner of the bounding box. This property is dimmed if the Tessellation Scheme is Geography grid.

  • Y-min
    Specifies the y-coordinate of the lower-left corner of the bounding box. This property is dimmed if the Tessellation Scheme is Geography grid.

  • Identity
    When expanded, shows the Name and Description property fields.

  • (Name)
    Shows the name of the spatial index. When a new index is created, it is given a default name based on the table in the active window in Table Designer. You can change the name at any time.

  • Description
    Describes the index. To write a more detailed description, click Description and then click the ellipsis button (…) that appears to the right of the property field. This provides a larger area in which to write text.

  • Table Designer Category
    When expanded, shows information about the properties of this spatial index.

  • Fill Specification
    When expanded, shows information for Fill Factor and Pad Index.

  • Fill Factor
    Specify what percentage of the index page the system can fill. Once a page is full, the system must split the page if new data is added, which impairs performance.

    • A value of 100 means the pages will be full; this requires the least amount of storage space but is the least efficient. This setting should be used only when there will be no changes to the data, for example, on a read-only table.

    • A lower value leaves more empty space on the data pages, which reduces the need to split data pages as indexes grow. However, it requires more storage space. This setting is more appropriate when there will be changes to the data in the table.

  • Pad Index
    Provide pages in this index the same percentage of empty space (padding) that is specified in Fill Factor.

  • Page Locks Allowed
    Specify whether page-level locking is allowed on this index. Allowing or disallowing page-level locking affects database performance.

  • Re-compute Statistics
    Specify whether to compute new statistics when the index is created. Re-computing statistics slows the building of indexes but usually improves query performance.

  • Row Locks Allowed
    Specify whether row-level locking is allowed on this index. Allowing or disallowing row-level locking affects database performance.