Oracle Architecture and Concepts

Redo log is a part of physical structure of oracle. its basic function is to record all the changesmade to daatabase information. wheneveer an abnormal shutdown take place preventing system to update the database, changes can be obtained from redolog and hence the changes are not lost.

1. Sum of the data files select sum(bytes/1024/1024/1024) 'Size in GB' from dba_data_files;

2. Actual data size:select sum(bytes/1024/1024/1024) 'Size in GB' from DBA_segments;