Blobspaces

A blobspace is a logical storage unit composed of one or more chunks that store only TEXT and BYTE data.

A blobspace stores TEXT and BYTE data in the most efficient way possible. You can store TEXT and BYTE columns associated with distinct tables (see Tables) in the same blobspace.

The database server writes data stored in a blobspace directly to disk. This data does not pass through resident shared memory. If it did, the volume of data might occupy so many of the buffer-pool pages that other data and index pages would be forced out. For the same reason, the database server does not write TEXT or BYTE objects that are assigned to a blobspace to either the logical or physical log. The database server logs blobspace objects by writing them directly from disk to the logical-log backup tapes when you back up the logical logs. Blobspace objects never pass through the logical-log files.

When you create a blobspace, you assign to it one or more chunks. You can add more chunks at any time. One of the tasks of a database server administrator is to monitor the chunks for fullness and anticipate the necessity to allocate more chunks to a blobspace. For instructions on how to monitor chunks for fullness, see Monitor simple large objects in a blobspace. For instructions on how to create a blobspace, add chunks to a blobspace, or drop a chunk from a blobspace, see Manage disk space.

For information about the structure of a blobspace, see the topics about disk structures and storage in the HCL Informix® Administrator's Reference.


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