> 备用 ``` sql --scn --针对速率的变化， 在11.2.0.4 及以上版， 请您先使用下面脚本检查是否SCN Rate是96K<Current SCN Compatibility=3 set serveroutput on; declare tmpn number; tmpd date; cur_scn_compat number; roll_to number; roll_enabled boolean; begin dbms_scn.GetCurrentSCNParams(tmpn,tmpn,tmpn,cur_scn_compat,tmpn); dbms_scn.GetSCNAutoRolloverParams(tmpd,roll_to,roll_enabled ); dbms_output.put_line('Current SCN Compatibility='||cur_scn_compat); if roll_enabled then dbms_output.put_line('Automatic Rollover to '||roll_to|| 'Enabled'); else dbms_output.put_line('Automatic Rollover to '||roll_to||' Disabled'); end if; end; / --scn增长速度 set numwidth 17 set pages 1000 alter session set nls_date_format='DD/Mon/YYYY HH24:MI:SS'; select * from (SELECT tim, gscn, round(rate), round((chk16kscn - gscn) / 24 / 3600 / 16 / 1024, 1) "Headroom" FROM (select tim, gscn, rate, ((((to_number(to_char(tim, 'YYYY')) - 1988) * 12 * 31 * 24 * 60 * 60) + ((to_number(to_char(tim, 'MM')) - 1) * 31 * 24 * 60 * 60) + (((to_number(to_char(tim, 'DD')) - 1)) * 24 * 60 * 60) + (to_number(to_char(tim, 'HH24')) * 60 * 60) + (to_number(to_char(tim, 'MI')) * 60) + (to_number(to_char(tim, 'SS')))) * (16 * 1024)) chk16kscn from (select FIRST_TIME tim, FIRST_CHANGE# gscn, ((NEXT_CHANGE# - FIRST_CHANGE#) / ((NEXT_TIME - FIRST_TIME) * 24 * 60 * 60)) rate from v$archived_log where (next_time > first_time))) order by 3 desc, 1, 2) where rownum < 11; --scn scripts ```