计算flash recovery area已经占用的空间:
SQL> select sum(percent_space_used)*3/100 from v$flash_recovery_area_usage;
SUM(PERCENT_SPACE_USED)*3/100
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0
如果flash recovery area空间不足导致db不能打开或是hang住的处理方法
Alter system set db_recovery_file_dest_size=3G scope=spfiel;