An explanation of the various indexes ArcView uses and how they are created.
- Spatial indexes
· A spatial index is automatically created, if one doesn't already exist, when you do a spatial join or a theme-on-theme selection.
· You can create a spatial index by using the Avenue request 'BuildIndex' on any coverage feature source.
· You can create a spatial index in ArcInfo with the INDEX command. ArcView will use that index.
You can determine whether a feature data source contains an index by using the Avenue request 'HasIndex'.
· You can also create a spatial index from the ArcView interface:
1. Open the theme's table.
2. Make the Shape field active.
3. Select Create Index from the Field menu.
If the menu only shows a Remove Index option, a spatial index already exists for that theme/coverage.
- Tabular indexes
Tabular indexes are created automatically by ArcView to support table links. These indexes are stored locally for the duration of the working session. If you save a project containing table links, the indexes will be recreated when you open the project again. Tabular indexes created by other programs, such as FoxPro or dBASE, cannot be used by ArcView at this time.
To create a tabular index:
1. Make the field you want to index active
2. Select Create Index from the Field menu
If the menu only shows a Remove Index option, an index already exists for the field you chose.
- Permanent and Local Indexes
ArcView may create permanent or local indexes, depending on the type of data being used.
A PERMANENT index is created inside the public filesystem, inside a coverage directory for example. This index is useable across multiple ArcView sessions and shareable among concurrent sessions.
PERMANENT SPATIAL indexes may be created for these sources shapefiles as well as all coverages except routes, nodes, and labels
PERMANENT TABULAR indexes will be created for fields in the base table when the table is in a writeable directory. These will be used for joins, links, and queries.
A LOCAL index is created in the project workspace and is automatically deleted at the end of the ArcView session. It provides the same functions and advantages to speed up spatial selections as a permanent index.
LOCAL SPATIAL indexes may be created for dynamic segmentation and event themes, for geocoding themes, and for library layers.
LOCAL TABULAR indexes will be created for fields in the base table when the table is not in a writeable directory or for fields not in the base table. These may be used for links and queries but cannot be used for joins.
- Read/Write Access
· SHAPEFILE DATA, FULL ACCESS
All index files are saved in the directory containing the working data.
When indexing the attribute field, the .ain file is the index file containing record data and .aih is the index file containing header (column) names.
When indexing the shape field, the .sbn and .sbx files are created.
When indexing a geocoding field, the .ixs and .mxs files are created. These files contain a time stamp from the local machine.
· SHAPEFILE DATA, READ ONLY
When indexing an attribute field, the vtab#.ain and vtab#.aih files are created in the TEMP directory and are deleted upon exiting ArcView.
When indexing a shape field, the .fbn and .fbx files are created and saved in the workspace directory.
When indexing a field for geocoding, the #.idx file is created in the working directory. A new index must be generated when the shapefile is used as the geocoding source. The path to the .idx file is stored in the project file. The # is not related to the shapefile name. If the shapefile name is longer than five digits and its last value is a number, the number will not be included in the .idx prefix.
· ARCINFO COVERAGES, FULL ACCESS
When indexing an attribute field, the .ain and .aih files are created within the Info folder in the directory containing the working data. ArcView does not recognize ArcINFO indexes.
When indexing the shape field, the pbn.adf and pbx.adf files are saved within the Info folder in the directory containing the working data.
When indexing a field for geocoding, the .ixc and .mxc files are saved in the directory containing the working data.
· ARCINFO COVERAGES, READ ONLY
Same as shapefile.
OTHER FEATURE TYPES, FULL ACCESS, such as DXF and DWG
When indexing an attribute filed, the vtab#.ain and vtab#.aih files are saved in the TEMP directory and have the same characteristics as the read only shapefile.
When indexing a shape field, the .abn and .abx files are saved in the directory containing the working data.
When indexing a field for geocoding, the .ixo and .mxo files are saved in the directory containing the working data.
· OTHER FEATURE TYPES, READ ONLY
Same as shapefile.