4-22 IBM Informix OnLine Database Server Administrator’s Guide
Blobspace Logging
Blobspace Logging
OnLine logs blobspace data in three steps, illustrated inFigure 4-2 on
page 4-23. Blobspace data does not pass through shared memory or the
logical log files on disk.
Following is an overview of steps in logging blobspace data:
1. Blobspacedata flows from the pipe, through temporary buffers in the
database server process memory space, and is written directly to
disk.If the blob requires more than one blobpage, links and pointers
are created as needed.
2. A record of the operation (insert, update, or delete) is written to the
logical log buffer, if the database uses logging. The blob data is not
included in the record.
3. When a logical log backup begins, OnLine uses the logical log ID
number stored in the blobspace free-map page to determine which
blobpages to copy to tape.