Oracle : Ошибка ORA-01668

"standby database requires DROP option for offline of data file"
*Cause: Attempting to take a datafile offline in a standby database without
specifying the DROP option. Files that are offline in a standby
database are not recovered, and are likely to be unusable if
the standby is activated. Note that specifying DROP does not
prevent bringing the file online later.
*Action: Specify the DROP option or leave the file online.

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