フリー問題

問題文

Which statement describes how the log of changes comes to hold old images at all, and what use may be made of that log besides recovery?

選択肢

1. The writing of an old image is itself a change to a segment, and the database records that change in the log along with the rest, so the log may be handed to a reader which rebuilds the old images and holds them once the tablespace has been filled.
2. The writing of an old image is itself a change to a segment, and the database notes it down beside the rest, so what stands there may be read through an interface of the query language in a utility which mines it for the history of the activity.
3. The old images of permanent objects are written to the log instead of to a segment to let one write serve both purposes, and the database keeps a pointer to them there, so the log may be read through an interface of the query language in a utility which mines it for the history of the activity with the pointers it keeps.
4. The old images of temporary objects rather than those of permanent ones reach the log where the segments which hold them lie outside the tablespace for old images, and the database records the rest elsewhere instead of both, so the log written with a pointer it keeps may be handed once to a reader which rebuilds the temporary tables from it after a failure.