Data Storage

Microsoft Jet uses a form of data storage known as the Indexed Sequential Access Method (ISAM). The Microsoft Jet ISAM implementation has the following characteristics:

• Records can be ordered by the use of an index on any field or combination of fields.
  
  
• Variable-length records are the standard method of storage.
  
  
• Data is stored and managed in 2 KB pages, similar to those in Microsoft SQL Server.

In Microsoft Jet, data stored in the database is structured as a set of pages, each containing one or more records. A record can’t span more than a single page; Memo and Long Binary (OLE Object) fields are stored in pages separate from the rest of the record. Each record occupies only as much space as needed to store its data, so each record within the same table may not be the same length.