Does Redo log have the details of the changes made but yet to be written in the database?

Question

Does the Redo log have the details of the changes made but yet to be written in the database?

Answer 1

The REDO log is a write-ahead log. Things are written there before they are written to the database (because it is more efficient to append changes to a sequential log than it is to in-place-update random database blocks spread all over the disk). They have to make it in there at the point of commit (so that the committed data can reliably be restored).

But they stay in the log until aged out. They are not removed when the database has been updated to also contain the value.