I just want to know the fallback technique in teradata. We want to apply fallback on more than 500 tables which are accessed more from users. Is there any technique to make the 500 tables fallback at a time. If I make them fallback on one shot, Is there any drawback on the system ?? Let me know whether we need downtime for this OR any other suggestion which will help me in doing this successfully without disturbing to the business.
You can make the tables fallback using ALTER table statement, and can take a lot of time depending on the records in the tables as the opertaion is a full-table scan. The system reads all the rows and distributes the rows on different AMP in the same CLUSTER, so all the AMPS should be online as well.
As it is time consuming task so not recommended during the business hours.
The problem with alter is that the table gets locked and will not be available for any user even though anyone is accessing through a view. if there is no space limitation on your system, to have minimal downtime for the users, create a new fallback table, insert select into the new table, verify the counts and then rename the tables and drop the old table. This way there will be minimal to no downtime and if this is done in a serial fashion can be done even during business hours.