The system has the ability to restore access paths and it usually restores an access path faster than it rebuilds it.
For example, assume that a logical file is built over a physical file that contains 500 000 records. You have determined through the Display Object Description (DSPOBJD) command that the size of the logical file is about 15 megabytes.
In this example, it takes about 50 minutes to rebuild the access path for the logical file. It takes about 1 minute to restore the same access path from a tape. (This assumes that the system builds approximately 10 000 index entries per minute.)
After restoring the access path, you might need to update the file by applying the latest journal changes. For example, the system applies approximately 80 000 to 100 000 journal entries to the file per hour. This assumes that each of the physical files to which entries are being applied has only one access path built over it. This rate drops proportionally for each access path of *IMMED maintenance that is present over the physical file. Even with this additional recovery time, you usually find that it is faster to restore access paths than to rebuild them.