Blob Database Storage

Go Up to What is a Blob?

Rather than storing Blob data directly in the Blob field of a table record, InterBase stores a Blob ID there. A Blob ID is a unique numeric value that references Blob data. The Blob data is stored elsewhere in the database, in a series of Blob segments, units of Blob data read and written in chunks. Blob segments can be of varying length. The length of an individual segment is specified when it is written.

Segments are handy when working with data that is too large for one application memory buffer. But it is not necessary to use multiple segments; you can put all your Blob data in a single segment.

When an application creates a Blob, it must write data to it a segment at a time. When an application reads a Blob, it reads a segment at a time. For more information about writing segments, see Writing Data to a Blob. For more information about reading segments, see Reading Data from a Blob.