The foremost statistic is the 'redo blocks written' value.This is most useful for finding how much redo is generated for an operation or time interval.
This indicates the time the user processes had to wait to get space in the redo file.
This indicates the number of repeated attempts to allocate space in the redo buffer. A value indicates that the redo writer is falling behind possibly due to a log switch. Although log switch is a normal event, frequent log switches indicate improper sizing of the redo log files.
Viewing Space Usage for Temporary Tablespaces
The DBA_TEMP_FREE_SPACE dictionary view contains information about space usage for each temporary tablespace. The information includes the space allocated and the free space. You can query this view for these statistics using the following command.