Use Read-only (-RO) to open a database for read-only access or to access a database stored on read-only media (a read-only optical disk, for example).

If you use the -RO parameter when other users are updating the database, you might see invalid data, such as stale data or index entries pointing to records that have been deleted.

A read-only session is essentially a single-user session. Read-only users do not share database resources (database buffers, lock table, index cursors). However, unlike a normal single-user database, a read-only database can be simultaneously accessed by multiple -RO users.

When a read-only session starts, it does not check for the existence of a lock file for the database. Furthermore, a read-only user opens the database file, but not the log or before-image files. Therefore, read-only user activity does not appear in the log file.

If a database is opened with -RO, the string returned by the DBRESTRICTIONS function includes the keyword READ-ONLY.