1. 监控事例的等待

    select event,sum(decode(wait_Time,0,0,1)) "Prev",    sum(decode(wait_Time,0,1,0)) "Curr",count(*) "Tot"     from v$session_Wait     group by event order by 4;

2. 回滚段的争用情况

    select name, waits, gets, waits/gets "Ratio"     from v$rollstat a, v$rollname b     where a.usn = b.usn;

3. 监控表空间的 I/O 比例

    select df.tablespace_name name,df.file_name "file",f.phyrds pyr,    f.phyblkrd pbr,f.phywrts pyw, f.phyblkwrt pbw    from v$filestat f, dba_data_files df    where f.file# = df.file_id    order by df.tablespace_name;

4. 监控文件系统的 I/O 比例

    select substr(a.file#,1,2) "#", substr(a.name,1,30) "Name",     a.status, a.bytes, b.phyrds, b.phywrts     from v$datafile a, v$filestat b     where a.file# = b.file#;

5.在某个用户下找所有的索引

    select user_indexes.table_name, user_indexes.index_name,uniqueness, column_name    from user_ind_columns, user_indexes    where user_ind_columns.index_name = user_indexes.index_name    and user_ind_columns.table_name = user_indexes.table_name     order by user_indexes.table_type, user_indexes.table_name,    user_indexes.index_name, column_position;

6. 监控 SGA 的命中率

    select a.value + b.value "logical_reads", c.value "phys_reads",    round(100 * ((a.value+b.value)-c.value) / (a.value+b.value)) "BUFFER HIT RATIO"     from v$sysstat a, v$sysstat b, v$sysstat c    where a.statistic# = 38 and b.statistic# = 39     and c.statistic# = 40;

7. 监控 SGA 中字典缓冲区的命中率

    select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 "miss ratio",    (1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 "Hit ratio"    from v$rowcache     where gets+getmisses <>0    group by parameter, gets, getmisses;

8. 监控 SGA 中共享缓存区的命中率，应该小于1%

    select sum(pins) "Total Pins", sum(reloads) "Total Reloads",    sum(reloads)/sum(pins) *100 libcache    from v$librarycache;

    select sum(pinhits-reloads)/sum(pins) "hit radio",sum(reloads)/sum(pins) "reload percent"     from v$librarycache;

9. 显示所有数据库对象的类别和大小

    select count(name) num_instances ,type ,sum(source_size) source_size ,    sum(parsed_size) parsed_size ,sum(code_size) code_size ,sum(error_size) error_size,    sum(source_size) +sum(parsed_size) +sum(code_size) +sum(error_size) size_required     from dba_object_size     group by type order by 2;

10. 监控 SGA 中重做日志缓存区的命中率，应该小于1%

    SELECT name, gets, misses, immediate_gets, immediate_misses,    Decode(gets,0,0,misses/gets*100) ratio1,    Decode(immediate_gets+immediate_misses,0,0,    immediate_misses/(immediate_gets+immediate_misses)*100) ratio2    FROM v$latch WHERE name IN ('redo allocation', 'redo copy');