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;
　

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

　　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;
　

　　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#;
　

　　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;
　

　　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;
　

　　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;
　

　　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;
　

　　select　 type,
　　count(name) num_instances,
　　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 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');
　

　　SELECT　 name, value
　　FROM　v$sysstat
　　WHERE　name IN ('sorts (memory)', 'sorts (disk)');
　

　　SELECT　 osuser, username, sql_text
　　from　v$session a, v$sqltext b
　　where　a.sql_address =b.address order by address, piece;
　

　　SELECT　 (SUM(PINS - RELOADS)) / SUM(PINS) "LIB CACHE"
　　FROM　V$LIBRARYCACHE;
　　SELECT　 (SUM(GETS - GETMISSES - USAGE - FIXED))
    / SUM(GETS) "ROW CACHE"
　　FROM　V$ROWCACHE;
　　SELECT　 SUM(PINS) "EXECUTIONS", SUM(RELOADS)
    "CACHE MISSES WHILE EXECUTING"
　　FROM　V$LIBRARYCACHE;
　　后者除以前者,此比率小于1%,接近0%为好。
　　SELECT　 SUM(GETS) "DICTIONARY GETS",
    SUM(GETMISSES) "DICTIONARY CACHE GET MISSES"
　　FROM　V$ROWCACHE;
　

　　select * from sys.props$ where name='NLS_CHARACTERSET';
　

　　select busy/(busy+idle) "shared servers busy" from v$dispatcher;
　　此值大于0.5时，参数需加大
　　select sum(wait)/sum(totalq) "dispatcher waits"
    from v$queue where type='dispatcher';
　　select count(*) from v$dispatcher;
　　select servers_highwater from v$mts;
　　servers_highwater接近mts_max_servers时，参数需加大
　

　　select　 tablespace_name,count(tablespace_name)
　　from　dba_free_space
　　group by tablespace_name
　　having count(tablespace_name)>10;
　　alter tablespace name coalesce;
　　alter table name deallocate unused;
　　create or replace view ts_blocks_v as
　　select　 tablespace_name,block_id,bytes,blocks,
　　segment_name
　　from　dba_free_space
　　union all
　　select　 tablespace_name,block_id,bytes,blocks,
　　segment_name
　　from　dba_extents;
　　select * from ts_blocks_v;
　　select　 tablespace_name,sum(bytes),max(bytes),count(block_id)
　　from　dba_free_space
　　group by tablespace_name;
　　查看碎片程度高的表
　　SELECT　 segment_name table_name , COUNT(*) extents
　　FROM　dba_segments
　　WHERE　owner NOT IN ('SYS', 'SYSTEM')
　　GROUP BY segment_name
　　HAVING COUNT(*) = (SELECT MAX(COUNT(*))
    FROM dba_segments GROUP BY segment_name);
　

　　select　 segment_name,sum(bytes),count(*) ext_quan
　　from　dba_extents
　　where　 tablespace_name='&tablespace_name' and
　　segment_type='TABLE'
　　group by tablespace_name,segment_name;
　　select　 segment_name,count(*)
　　from　dba_extents
　　where　segment_type='INDEX' and owner='&owner'
　　group by segment_name;
　

　　12是cpu used by this session
　　select　 a.sid,spid,status,substr(a.program,1,40) prog,
　　a.terminal,osuser,value/60/100 value
　　from　v$session a,v$process b,v$sesstat c
　　where　c.statistic#=12 and
　　c.sid=a.sid and
　　a.paddr=b.addr
　　order by value desc;