Logging Blobspaces and Simple Large Objects

Simple-large-object data (TEXT and BYTE data types) is potentially too voluminous to include in a logical-log record. If simple large objects are always logged, they might be so large that they slow down the logical log.

The database server assumes that you designed your databases so that smaller simple large objects are stored in dbspaces and larger simple large objects are stored in blobspaces:

• The database server includes simple-large-object data in log records for simple large objects stored in dbspaces.
• The database server does not include simple-large-object data in log records for simple large objects stored in blobspaces. The logical log records blobspace data only when you back up the logical logs.

To obtain better overall performance for applications that perform frequent updates of simple large objects in blobspaces, reduce the size of the logical log. Smaller logs can improve access to simple large objects that must be reused. For more information, see the chapter on configuration effects on I/O utilization in your IBM Informix Dynamic Server Performance Guide.