Oracle Log Files Explained: Redo & Archive Logs

In Oracle databases, log files mainly consist of redo log files and archive log files.

1. Repeated log files: Redo logs are files that record all modification operations (such as insert, update, delete) that occur in a database, capturing changes in the database in order to recover it in the event of a failure. Redo log files are typically organized in groups, each containing one or more members that are written to in a circular manner. When a modification operation is performed in the database, the related redo log records are first written to the redo log buffer, and then to the redo log file.
2. Archived log files are generated when a database is set to archive mode and contain all changes made to the database. These files are used for recovery in case of a database failure. When the database is in archive mode, redo log files are automatically switched to archived log files to ensure they are not overwritten. The archived log files are typically saved in a specified directory for recovery purposes.

In general, log files play a critical role in Oracle databases, ensuring effective recovery in case of failures and maintaining data integrity and consistency.