Simple Large Objects and RSS
David Grove asked how simple large objects in a blobspace reach an RSS secondary on 12.10.FC14. Art Kagel said they do not replicate under RSS or HDR; only in-table blobs replicate, and smart blobs do if the sbspace is logged. Grove decided not to move the legacy objects to a blobspace.
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Informix 12.10.FC14 Solaris 10 1/13 Folks, We use RSS for a database for reliability-- in case of an unforeseen disaster at one location, we have a mirror copy of the database at another city in the state, about 700 miles away. We have a few older (legacy) tables that have in-table Simple Large Objects. In-table Simple Large Objects are logged. We'd like to move those Simple Large Objects to their own blobspace. But, the documentation states: 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. Given that it isn't logged, how does simple large object data stored in blobspaces get transferred to an RSS? Thank you for any comments. DG ------------------------------ David Grove ------------------------------ #Informix
They don't David. Blobspace dumb blobs do not replicate under RSS or HDR! Only tablespace dumb blobs replicate. Smartblobs replicate if the smartblobspace is a logged space (default is logged but you can create an unlogged smartblobspace). Rollbacks and archive recovery of dumb blobs is handled by not overwriting dumb blobs but by creating a new copy and marking the previous version to be deleted after the next archive. As part of the archive defunct blob versions are physically removed and their space freed for reuse. As noted in the docs, the logical log backups also copy the defunct copy of the blobs to the log backup, but they are never really part of the logging. Art ------------------------------ Art S. Kagel, President and Principal Consultant ASK Database Management Corp. www.askdbmgt.com ------------------------------
Thank you, tremendously! I had never realized that. Guess we won't be using a separate BLOB Space for those rascals. We would have converted them to Smart Large Objects, but not now, due to management's future plans. We do use logged sbspaces for our smart large objects (which is what we use for our more current LOB needs). RSS works like a charm for our needs. DG ------------------------------ David Grove ------------------------------
Our Simple Large Objects were originally for photos. Those objects are mostly no longer used, but they were created back in the early 2000s, or before. Long before replication was even a twinkle in anyone's eye. Subsequently, some TEXT objects were also created. Some even within the last 10 years. But, they are all in-table objects, which is why they have never been an issue w.r.t.replication. Sigh. ------------------------------ David Grove ------------------------------