Before you create a new geodatabase, you first need to decide which kind of geodatabase you want to create. There are three kinds of geodatabases from which to choose:
A file geodatabase stores datasets in a folder of files on your computer. Each dataset is held as a file and can be up to 1 TB in size (and you can optionally configure a file geodatabase to store much larger datasets). File geodatabases can be used across platforms and can be compressed and encrypted for read-only, secure use.
NOTE: If you do not know what kind of geodatabase you want to create, this is a good default choice.
A personal geodatabase stores its datasets in a Microsoft Access .mdb file on disk. The storage sizes of personal geodatabases are effectively limited to between 250 and 500 MB for the entire geodatabase and are only supported on Windows. Users often need larger storage for their datasets, so they choose file or ArcSDE geodatabases.
An ArcSDE geodatabase stores datasets in a number of optional DBMSs including
Oracle
Oracle with Locator or Spatial
SQL Server
DB2
Informix
PostgreSQL
If you want to manage versions or historical archives in your geodatabase, you need to use ArcSDE geodatabases.
ArcSDE geodatabase options
There are two types of ArcSDE geodatabases:
ArcSDE for SQL Server Express—ArcGIS Desktop at the ArcEditor and ArcInfo license levels, ArcGIS Engine, and ArcGIS Server Workgroup edition ship with SQL Server Express. You can install SQL Server Express, which is a lightweight, personal copy of SQL Server, and enable it to store ArcSDE geodatabases. With ArcCatalog, you can set up and administer a SQL Server Express instance as well as ArcSDE geodatabases, so you do not have to be a database administrator (DBA) to use these types of ArcSDE geodatabases. When licensed through ArcGIS Desktop or ArcGIS Engine, up to three users can connect to the SQL Server Express instance. When licensed through ArcGIS Server Workgroup, 10 desktop clients and any number of Web clients can connect to the SQL Server Express instance.
ArcSDE geodatabases licensed with ArcGIS Server Enterprise—In addition, ArcSDE can work in enterprise settings across a range of DBMSs using ArcSDE Enterprise geodatabases. ArcSDE Enterprise is purchased as part of ArcGIS Server Enterprise level and typically requires DBA privileges and skills to set up and administer the underlying DBMS.
