Oracle : Ошибка ORA-38753

"Cannot flashback data file %s; no flashback log data."
*Cause: An attempt to perform a FLASHBACK DATABASE failed because the file
does not have enough flashback log data to cover the time to
flash back. Either the file did not have flashback generation
enabled for it, or had flashback generation turned off for it
some time during the time span of the flashback.
*Action: The file cannot be flashed back. The file must be taken offline
or the tablespace dropped before continuing with the FLASHBACK
DATABASE command.

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