How data converts when importing

When you import data that is in a format not used by the geodatabase, ArcGIS automatically converts it into data types used by the geodatabase. The following describes how different formats are converted during the importing process.

Importing ArcInfo coverages

When you import coverages and INFO tables into the geodatabase, ArcGIS automatically converts the coverage geometry and fields to types used by the geodatabase. This section describes how coverages are converted into geodatabase content.

All feature class types within ArcInfo coverages convert to one of four fundamental geometry types in the geodatabase (points, lines, polygons, or annotation). Each coverage feature class becomes a new geodatabase feature class. For example, point feature classes, tic feature classes, and node feature classes all convert to separate point feature classes in the geodatabase. The following table illustrates how feature class types convert to geodatabase geometry types.

Coverage feature class	Geodatabase geometry
Point	Point
Arc	Line (polyline)
Polygon	Polygon
Node	Point
Tic	Point
Region	Polygon
Route	Line (polyline) with measures
Annotation	Annotation

This table illustrates how feature class types convert to geodatabase geometry types.

All attribute types in coverages and INFO tables convert to field types in the geodatabase. Coverage and INFO table items convert based on a combination of their type and width. For example, you can map an item type to a short integer, long integer, or double, depending on its width. The following table summarizes how items convert.

INFO item type	INFO item width	Geodatabase field type
B	4	Long integer
C	1–320	Text
D	8	Date
F	4	Float
F	8	Double
I	1–4	Short integer
I	5–9	Long integer
I	10–16	Double
N	1–9	Float
N	10–16	Double

This table summarizes how items convert.

Coverages contain several fields that are relevant to the coverage data model only and are not maintained by the geodatabase; therefore, you should determine if you want to import them.

The following is recommended in most cases:

• When importing polygon or point coverages, don't import <cover#>, AREA, or PERIMETER.
• When importing line coverages, don't import <cover#>, RPOLY#, LPOLY#, FNODE, TNODE, or LENGTH.
• If the coverage you're importing doesn't use the <cover-ID> field to relate to another table, don't import this field.

Importing ESRI shapefiles

When you import shapefiles and dBASE tables into the geodatabase, ArcGIS automatically converts the shapefile geometry and fields to types used by the geodatabase. This section describes how shapefiles are converted into geodatabase content.

The geometry types for points, lines, and polygons in ESRI shapefiles are similar to the corresponding geodatabase feature class types. Therefore, importing shapefile datasets into geodatabases is relatively straightforward.

All feature types in shapefiles convert to geometry types in the geodatabase as denoted in the following table.

Shapefile feature class	Geodatabase geometry
Point	Point
Point M	Point with measures
Point Z	Point with z-values
Polyline	Line (polyline)
Polyline M	Line (polyline) with measures
Polyline Z	Line (polyline) with z-values
Polygon	Polygon
Polygon M	Polygon with measures
Polygon Z	Polygon with z-values
Multipoint	Multipoint
Multipoint M	Multipoint with measures
Multipoint Z	Multipoint with z-values
Multipath	Multipath

This table shows how shapefile feature classes are converted to geodatabase geometry.

Each shapefile and dBASE field type converts to a single geodatabase field type, except for the Number type field. The following table summarizes how shapefile and dBASE field types convert.

Field type	Field width	Geodatabase field type
Date	NA	Date
String	1–255	Text
Boolean	NA	Short integer
Number	1–4 (decimals=0)	Short integer
Number	5–9 (decimals=0)	Long integer
Number	10–19 (decimals=0)	Double
Float	1–13	Float
Float	14–19	Double
Number	1–8 (decimals>0)	Float
Number	9–19 (decimals>0)	Double

This table summarizes how shapefile and dBASE field types convert.

Importing CAD data

When you import computer-aided drafting (CAD) data files into the geodatabase, ArcGIS automatically converts the CAD geometry and fields to types used by the geodatabase. See Import from CAD (conversion) to read how CAD elements are converted into geodatabase content.

Importing existing ArcSDE data tables into the geodatabase

If you have been a longtime user of ArcSDE, you may have legacy datasets in ArcSDE that need to be imported into the geodatabase. For example, you may have previously loaded data into an ArcSDE database using an ArcSDE command such as shp2sde.

Or perhaps you have written a C program to load data that uses the ArcSDE C application programming interface (API).

The process used to add these existing ArcSDE datasets to the geodatabase is straightforward. It is not so much a process to import the existing dataset as it is one where you register the dataset with the geodatabase.

Registering an existing ArcSDE data table in ArcCatalog or the Catalog window

1. In the Catalog tree, right-click the table or feature class you want to register with the geodatabase.
2. Click Register with Geodatabase.

Registering an ArcSDE layer or table adds an ObjectID field to the table. This field name is OID for tables and FID for feature classes. If an OID or FID field already exists in the table or layer, then another name is automatically added to the registered table.

Importing data to a personal geodatabase

When you import a feature class from an ArcSDE geodatabase into a personal geodatabase, any text fields that contain more than 255 characters are created as memo fields in Microsoft Access. Personal geodatabases interpret this memo field as a BLOB and set the field length in ArcGIS to 2,147,483,647 characters. This could have implications if you later attempt to copy this feature class from the personal geodatabase to another ArcSDE geodatabase. Most database management systems do not support text fields of this length.