Last week we discovered a problem with the WSS August CU.
Due to schema and stored procedure changes coming with the August CU databases with a patch level older than the August CU cannot be upgraded to August CU through database attach method.
That means that you need to be careful when upgrading your WSS or MOSS farm to August CU as the usual recommended steps to detach the content database before installing the hotfix will cause problems later when you are going to reattach the databases. In case you need to install the August CU now to resolve an issue that is covered by the fix you should avoid detaching the content databases during the hotfix installation. If the databases are attached the hotfix installation will correctly upgrade the database when running PSCONFIG.
In case you need to detach the databases it would be required to upgrade the database in a separate farm before attaching them back to the production database. E.g. install a test farm with the previous build level the databases, attach the databases there and then upgrade the test farm to August CU. Afterwards you can detach the upgraded databases from the test farm and attach them back to the production farm.
Also be aware that this will also affect database backups taken before installing August CU.
The product group is currently actively investigating this issue to identify a more elegant method to avoid this problem.
[Update: the WSS hotfix has been rereleased on October 1st. The version of the WSS August 2009 CU availble now does no longer have this problem.]
Are you 100% sure that schema should be updated when i restore MOSS backup on server with higer SP/CU? There is a possibility that product was designed this way,
SharePoint requires the DBs to have the schema version of the product. It always tries to automatically upgrade the scheme when attaching.
Here it will fail and the databases will be unusable.
That is not "as designed".
So can you confirm that this logic apply to all MOSS database, especial to Project server databases ? I notice that after SP2 DB schema isn't upgraded when i restore backup from MPS without SP2.
I'm not familiar with Project Server and whether this product uses additional databases, so I cannot talk about these. All WSS or MOSS content databases will automatically be updated when attaching the db.
I can answer for Project Server. The Project Server databases aren't content databases - so there isn't really the concept of attaching them - and you certainly should NOT detach during the application of a SP or CU. The config wizard will update them, or if you restore old Project Server databases and then provision a new PWA site they will get updated to the latest schema during the provision process. Hope this helps - and great blog Stefan.