With flashback, you can look at data at a previous point in time. You can go back to the last DDL that occurred on a table. You are also constrained by the undo retention period specified by the Oracle database parameters. There are a couple types of flashback you can employ:
- FQ - Flashback Query
- FVQ - Flashback Query Version
- FTQ - Flashback Transaction Query
FVQ gives you rows that represent committed versions of data. Note that if you insert/update and then delete rows in a transaction, those operations do not show up in the FVQ. You only see material changes per transaction. You SELECT data whose VERSIONS are between TIMESTAMP values. You can also look between SCN ranges too. FVW does not work on views.
FTQ is running queries against the FLASHBACK_TRANSACTION_QUERY view. Working with this technology involves the global transaction identifier (XID). It is a RAW value tied to the transaction the change was made in. You can look at the value using the RAWTOHEX() function. Basically you want to query the view using some value(s) of the XID.