常用的一些性能查询sql语句

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--查看表锁
select * from sys.v_$sqlarea where disk_reads>100

--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

--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

--查看前台正在发出的SQL语句
select user_name, sql_text 　　
from v$open_cursor 　　
where sid in (select sid
                 from (select sid, serial#, username, program 　　
                         from v$session 　　
                        where status = 'ACTIVE'))

--数据表占用空间大小情况
select segment_name, tablespace_name, bytes, blocks
from user_segments
where segment_type = 'TABLE'
ORDER BY bytes DESC, blocks DESC

--查看表空间碎片大小
select tablespace_name,
       round(sqrt(max(blocks) / sum(blocks)) *
             (100 / sqrt(sqrt(count(blocks)))),
             2) FSFI
from dba_free_space
group by tablespace_name
order by 1

--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);

--查看表空间占用磁盘情况
select b.file_id 文件id,
       b.tablespace_name 表空间名,
       b.bytes / 1024 / 1024 总大小,
       (b.bytes - sum(nvl(a.bytes, 0))) / 1024 / 1024 已使用大小,
       sum(nvl(a.bytes, 0)) / 1024 / 1024 剩余空间,
       sum(nvl(a.bytes, 0)) / (b.bytes) * 100 剩余百分比
from dba_free_space a, dba_data_files b
where a.file_id = b.file_id
group by b.tablespace_name, b.file_id, b.bytes
order by b.file_id;

--查看session使用回滚段
SELECT r.name 回滚段名,
       s.sid,
       s.serial#,
       s.username 用户名,
       t.status,
       t.cr_get,
       t.phy_io,
       t.used_ublk,
       t.noundo,
       substr(s.program, 1, 78) 操作程序
FROM sys.v_$session s, sys.v_$transaction t, sys.v_$rollname r
WHERE t.addr = s.taddr
   and t.xidusn = r.usn
ORDER BY t.cr_get, t.phy_io

--查看SGA区剩余可用内存
select name,
       　　　　　　sgasize / 1024 / 1024　　　　　　　　"Allocated(M)",
       　　　　　　bytes / 1024/1024　　　　　　　　　　"自由空间(M)",
       　　　　　　round(bytes / sgasize * 100, 2) 　　"自由空间百分比(%)" 　　
from (select sum(bytes) sgasize from sys.v_$sgastat) s,
       sys.v_$sgastat f 　　
where f.name = 'free memory'

--监控表空间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;

--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#

--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;

--表、索引的存储情况检查
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;

--监控SGA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# = 48
   and b.statistic# = 51
   and c.statistic# = 55;

--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;

--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;

--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');

--监控内存和硬盘的排序比率，最好使它小于 .10
SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts (disk)');

--监控字典缓冲区
SELECT SUM(GETS) "DICTIONARY GETS",SUM(GETMISSES) "DICTIONARY CACHE GET MISSES" FROM V$ROWCACHE

--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;

--监控当前数据库谁在运行什么SQL 语句
SELECT osuser, username, sql_text
from v$session a, v$sqltext b
where a.sql_address = b.address
order by address, piece;

--v$dispatcher
select busy/(busy+idle) "shared servers busy" from v$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$SHARED_SERVER_MONITOR;--servers_highwater接近MAX_SHARED_SERVERS时，参数需加大

--非系统用户建在SYSTEM表空间中的表
SELECT owner, table_name
FROM DBA_TABLES
WHERE tablespace_name in ('SYSTEM', 'USER_DATA')
   AND owner NOT IN
       ('SYSTEM', 'SYS', 'OUTLN', 'ORDSYS', 'MDSYS', 'SCOTT', 'HOSTEAC')

--性能最差的SQL
SELECT * FROM ( SELECT PARSING_USER_ID EXECUTIONS,SORTS,COMMAND_TYPE,DISK_READS,sql_text
                FROM v$sqlarea
                ORDER BY disk_reads DESC)
WHERE ROWNUM<100;

--读磁盘数超100次的sql
select * from sys.v_$sqlarea where disk_reads>100;

--最频繁执行的sql
select * from sys.v_$sqlarea where executions>100

--查询使用CPU多的用户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

--当前每个会话使用的对象数
SELECT a.sid, s.terminal, s.program, count(a.sid)
FROM V$ACCESS a, V$SESSION s
WHERE a.owner <> 'SYS'
   AND s.sid = a.sid
GROUP BY a.sid, s.terminal, s.program
ORDER BY count(a.sid)

--监控log_buffer的使用情况：(值最好小于1%，否则增加log_buffer 的大小)
select rbar.name,
       rbar.value,
       re.name,
       re.value,
       (rbar.value * 100) / re.value || '%' "radio"
from v$sysstat rbar, v$sysstat re
where rbar.name = 'redo buffer allocation retries'
   and re.name = 'redo entries';

--查看运行过的SQL 语句：
SELECT SQL_TEXT FROM V$SQL

--客户端主机信息 SYS_CONTEXT sys_context函数调用userenv命名空间来获取相关信息
select SYS_CONTEXT('USERENV', 'TERMINAL') terminal,
       SYS_CONTEXT('USERENV', 'LANGUAGE') language,
       SYS_CONTEXT('USERENV', 'SESSIONID') sessionid,
       SYS_CONTEXT('USERENV', 'INSTANCE') instance,
       SYS_CONTEXT('USERENV', 'ENTRYID') entryid,
       SYS_CONTEXT('USERENV', 'ISDBA') isdba,
       SYS_CONTEXT('USERENV', 'NLS_TERRITORY') nls_territory,
       SYS_CONTEXT('USERENV', 'NLS_CURRENCY') nls_currency,
       SYS_CONTEXT('USERENV', 'NLS_CALENDAR') nls_calendar,
       SYS_CONTEXT('USERENV', 'NLS_DATE_FORMAT') nls_date_format,
       SYS_CONTEXT('USERENV', 'NLS_DATE_LANGUAGE') nls_date_language,
       SYS_CONTEXT('USERENV', 'NLS_SORT') nls_sort,
       SYS_CONTEXT('USERENV', 'CURRENT_USER') current_user,
       SYS_CONTEXT('USERENV', 'CURRENT_USERID') current_userid,
       SYS_CONTEXT('USERENV', 'SESSION_USER') session_user,
       SYS_CONTEXT('USERENV', 'SESSION_USERID') session_userid,
       SYS_CONTEXT('USERENV', 'PROXY_USER') proxy_user,
       SYS_CONTEXT('USERENV', 'PROXY_USERID') proxy_userid,
       SYS_CONTEXT('USERENV', 'DB_DOMAIN') db_domain,
       SYS_CONTEXT('USERENV', 'DB_NAME') db_name,
       SYS_CONTEXT('USERENV', 'HOST') host,
       SYS_CONTEXT('USERENV', 'OS_USER') os_user,
       SYS_CONTEXT('USERENV', 'EXTERNAL_NAME') external_name,
       SYS_CONTEXT('USERENV', 'IP_ADDRESS') ip_address,
       SYS_CONTEXT('USERENV', 'NETWORK_PROTOCOL') network_protocol,
       SYS_CONTEXT('USERENV', 'BG_JOB_ID') bg_job_id,
       SYS_CONTEXT('USERENV', 'FG_JOB_ID') fg_job_id,
       SYS_CONTEXT('USERENV', 'AUTHENTICATION_TYPE') authentication_type,
       SYS_CONTEXT('USERENV', 'AUTHENTICATION_DATA') authentication_data
from dual;

--查看回滚段名称及大小
SELECT a.owner || '.' || a.segment_name roll_name,
       a.tablespace_name tablespace,
       TO_CHAR(a.initial_extent) || ' / ' || TO_CHAR(a.next_extent) in_extents,
       TO_CHAR(a.min_extents) || ' / ' || TO_CHAR(a.max_extents) m_extents,
       a.status status,
       b.bytes bytes,
       b.extents extents,
       d.shrinks shrinks,
       d.wraps wraps,
       d.optsize opt
FROM dba_rollback_segs a, dba_segments b, v$rollname c, v$rollstat d
WHERE a.segment_name = b.segment_name
   AND a.segment_name = c.name(+)
   AND c.usn = d.usn(+)
ORDER BY a.segment_name;

--parse to excute ratio（数据库的SQL语句执行和分析的比例）越大越好
select round((1 - a.VALUE / b.VALUE )* 100, 2) "parse to excute ratio"
from v$sysstat a, v$sysstat b
where a.STATISTIC#=331 and b.STATISTIC#=330;

--Parse CPU to Parse Elapsed(指数据库用在分析的CPU的时间和分析完成CPU时间对比)
select round((1 - a.VALUE / b.VALUE )* 100, 2) "Parse CPU to Parse Elapsed"
from v$sysstat a, v$sysstat b
where a.STATISTIC#=328 and b.STATISTIC#=329;

--Non-Parse CPU(用在非分析的过程中CPU 的等待了其它的资源)
select round((1 - a.VALUE / b.VALUE )* 100, 2) "Non-Parse CPU"
from v$sysstat a, v$sysstat b
where a.STATISTIC#=328 and b.STATISTIC#=12;

--Rollback segment(等待rollback segment 的header 比率,比率越小越好)
select waits,gets,round(waits/gets*100,2) from v$rollstat a,v$rollname b where a.USN=b.usn

--表字段的注释说明
select * from user_col_comments
数据字典：
select * from dict order by table_name;
锁及资源信息：
select * from v$lock;不包括DDL锁
数据库字符集：
select * from sys.props$ where name='NLS_CHARACTERSET';
inin.ora参数：
select name,value from v$parameter order by name;
SQL 共享池：
select sql_text from v$sqlarea;
数据库：
　　select * from v$database
控制文件：
　　select * from V$controlfile;
重做日志文件信息：
　　select * from V$logfile;
来自控制文件中的日志文件信息：
　　select * from V$log;
来自控制文件中的数据文件信息：
　　select * from V$datafile;
NLS参数当前值：
　　select * from V$nls_parameters;
ORACLE 版本信息：
　　select * from v$version;
描述后台进程：
　　select * from v$bgprocess;
查看版本信息：
　　select * from product_component_version;