What constitutes a VLDB? These days, with databases scaling into hundreds of gigabytes and even terabytes, what constitutes a VLDB is hard to define. However, a database can be said to be a VLDB if it is too large to be maintained within the window of opportunity. The window of opportunity is the time when the database is quiet, the time you have allocated to perform maintenance tasks such as backing up the database. For example, if this window of opportunity is only one hour, then a database could be said to be a VLDB if its backup time exceeds that period. On the other hand, a database 10 times that size, with a 12- hour backup window, might not be considered a VLDB.