Structure of a Dbspace Blobpage
TEXT or BYTE data that is stored in the dbspace is stored in a blobpage. The structure of a dbspace blobpage is similar to the structure of a dbspace data page. The only difference is an extra 12 bytes that can be stored along with the TEXT or BYTE data in the data area.
Simple large objects can share dbspace blobpages if more than one simple large object can fit on a single page, or if more than one trailing portion of a simple large object can fit on a single page.
For a discussion of how to estimate the number of dbspace blobpages needed for a specific table, see your Informix® Performance Guide.
Each segment of TEXT or BYTE data stored in a dbspace page might be preceded by up to 12 bytes of information that does not appear on any other dbspace page. These extra bytes are overhead.