1. A method for responding to a change made in a database system, the method comprising the steps of: reading one or more entries from a log, said one or more entries identifying a change in a database, said one or more entries further identifying a change time at which the change occurred in the database; based on the entries read from the log, after said change time, generating a record of said change, the step of generating said record being performed asynchronously relative to when the change is made; after said change time, reading said record of said change, thereby detecting that said change occurred in the database at said change time, the step of reading said record being performed asynchronously relative to when the record is generated; in response to detecting that said change occurred at said change time, at a second time occurring after the change time, executing a flashback query to determine at least some aspects of the state of the database system at said change time, wherein the flashback query specifies a query to be performed based on first data, as the first data had existed at a time that is based on said change time; wherein the database system generates new entries for the log synchronously with committing changes to the database; and performing, by using a computer, an action in response to said change based on results of said flashback query.