Index Item (Coverage)
Summary
Creates an attribute index to increase access speed to the specified item during query operations.
Usage
-
Indexed items speed up selection operations of large INFO files.
-
Item indexes are preserved when the coverage or INFO table is copied to a new location.
-
Item indexes are preserved when exporting and importing a coverage to an interchange (.e00) file using the Export To Interchange File and Import From Interchange File tools.
-
Items must be indexed to support native mode reselects against external database management system (DBMS) tables.
-
An index file becomes outdated if the following commands are used on the INFO table: Calculate Field, Update, Build, or Clean. Attempting to use the outdated index will cause the following message to be generated: "Index file is obsolete." If you receive this message, rebuild the index file and continue.
-
The following commands are affected by indexed items: Eliminate, Select, and Join Info Tables.
Syntax
| Parameter | Explanation | Data Type |
in_info_table |
The name of the INFO table containing the item to be indexed | ArcInfo table |
index_item |
The name of the item to be indexed | ArcInfo item |
Code Sample
The following stand-alone script demonstrates how to index an item in a coverage, and then select features using the indexed item.
# Name: IndexItem_Example.py # Description: Indexes an item then uses that item to select features. # Requirements: ArcInfo Workstation # Author: ESRI # Import system modules import arcpy from arcpy import env # Set environment settings env.workspace = "C:/data" # Set local variables inInfoTable = "stream/arc" indexItem = "STRM_ORD" inCover = "stream" outCover = "C:/output/lowerstreams" infoExpress = ["RESELECT STRM_ORD > 3"] # Execute IndexItem arcpy.IndexItem_arc(inInfoTable, indexItem) arcpy.Reselect_arc(inCover, outCover, infoExpress)