ORACLE常用傻瓜問題1000問(之四)

Oracle常用傻瓜問題1000問(之四)作者:; CCBZZP ;;;;;大家在應用ORACLE的時候可能會碰到很多看起來不難的問題, 特別對新手來說, 今天我簡單把它總結一下, 發布給大家, 希望對大家有幫助! 和大家一起探討, 共同進步! 對ORACLE高手來說是不用看的. 虚擬字段133. CURRVAL 和 nextval 为表创建序列 CREATE SEQUENCE EMPSEQ ... ; SELECT empseq.currval FROM DUAL ; 自动插入序列的数值 INSERT INTO emp VALUES (empseq.nextval, 'LEWIS', 'CLERK', 7902, SYSDATE, 1200, NULL, 20) ;134. ROWNUM 按设定排序的行的序号 SELECT * FROM emp WHERE ROWNUM < 10 ;135. ROWID 返回行的物理地址 SELECT ROWID, ename FROM emp; WHERE deptno = 20 ;136. 将N秒转换为时分秒格式？ set serverout on declare N number := 1000000; ret varchar2(100); begin ret := trunc(n/3600) '小时' to_char(to_date(mod(n,3600),'sssss'),'fmmi'分'ss'秒'') ; dbms_output.put_line(ret); end; 137. 如何查询做比较大的排序的进程？ SELECT b.tablespace, b.segfile#, b.segblk#, b.blocks, a.sid, a.serial#, a.username, a.osuser, a.status FROM v$session a,v$sort_usage b WHERE a.saddr = b.session_addr ORDER BY b.tablespace, b.segfile#, b.segblk#, b.blocks ;138. 如何查询做比较大的排序的进程的SQL语句？ select /*+ ORDERED */ sql_text from v$sqltext a where a.hash_value = ( select sql_hash_value from v$session b where b.sid = &sid and b.serial# = &serial) order by piece asc ;139. 如何查找重复记录？ SELECT * FROM TABLE_NAME WHERE ROWID!=(SELECT MAX(ROWID) FROM TABLE_NAME D WHERE TABLE_NAME.COL1=D.COL1 AND TABLE_NAME.COL2=D.COL2); 140. 如何删除重复记录？ DELETE FROM TABLE_NAME WHERE ROWID!=(SELECT MAX(ROWID) FROM TABLE_NAME D WHERE TABLE_NAME.COL1=D.COL1 AND TABLE_NAME.COL2=D.COL2); 141. 如何快速编译所有视图？ SQL >SPOOL VIEW1.SQL SQL >SELECT ‘ALTER VIEW ‘TNAME’ COMPILE;’ FROM TAB; SQL >SPOOL OFF 然后执行VIEW1.SQL即可。 SQL >@VIEW1.SQL;142. ORA-01555 SNAPSHOT TOO OLD的解决办法 增加MINEXTENTS的值，增加区的大小，设置一个高的OPTIMAL值。 143. 事务要求的回滚段空间不够，表现为表空间用满（ORA-01560错误），回滚段扩展到达参数;;;MAXEXTENTS的值（ORA-01628）的解决办法. 向回滚段表空间添加文件或使已有的文件变大；增加MAXEXTENTS的值。 144. 如何加密ORACLE的存储过程？ 下列存储过程内容放在AA.SQL文件中 create or replace procedure testCCB(i in number) as begin dbms_output.put_line('输入参数是'to_char(i)); end; SQL>wrap iname=a.sql; PL/SQL Wrapper: Release 8.1.7.0.0 - ProdUCtion on Tue Nov 27 22:26:48 2001 Copyright (c) Oracle Corporation 1993, 2000.; All Rights Reserved. Processing AA.sql to AA.plb 运行AA.plb SQL> @AA.plb ;145. 如何监控事例的等待？ select event,sum(decode(wait_Time,0,0,1)) 'Prev', sum(decode(wait_Time,0,1,0)) 'Curr',count(*) 'Tot' from v$session_Wait group by event order by 4; 146. 如何回滚段的争用情况？ select name, waits, gets, waits/gets 'Ratio' from v$rollstat C, v$rollname D where C.usn = D.usn; 147. 如何监控表空间的 I/O 比例？ select B.tablespace_name name,B.file_name 'file',A.phyrds pyr, A.phyblkrd pbr,A.phywrts pyw, A.phyblkwrt pbw from v$filestat A, dba_data_files B where A.file# = B.file_id order by B.tablespace_name; 148. 如何监控文件系统的 I/O 比例？ select substr(C.file#,1,2) '#', substr(C.name,1,30) 'Name', C.status, C.bytes, D.phyrds, D.phywrts from v$datafile C, v$filestat D where C.file# = D.file#; 149. 如何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; 150. 如何监控 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$sysstat c where a.statistic# = 38 and b.statistic# = 39 and c.statistic# = 40; 151. 如何监控 SGA 中字典缓冲区的命中率？ select parameter, gets,Getmisses , getmisses/(gets+getmisses)*100 'miss ratio', (1-(sum(getmisses)/ (sum(gets)+sum(getmisses))))*100 'Hit ratio' from v$rowcache where gets+getmisses <>0 group by parameter, gets, getmisses; 152. 如何监控 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; 153. 如何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; 154. 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$latch WHERE name IN ('redo allocation', 'redo copy'); 155. 监控内存和硬盘的排序比率，最好使它小于 .10，增加 sort_area_size SELECT name, value FROM v$sysstat WHERE name IN ('sorts (memory)', 'sorts;;;(disk)'); 156. 如何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; 157. 如何监控字典缓冲区？ 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 158. 监控 MTS 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 159. 如何知道当前用户的ID号? SQL>SHOW USER; OR SQL>select user from dual;160. 如何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); 162. 如何知道表在表空间中的存储情况? 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; 163. 如何知道索引在表空间中的存储情况? select segment_name,count(*) from dba_extents where segment_type='INDEX' and;;;;owner='&owner' group by segment_name; 164、如何知道使用CPU多的用户session? 11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#=11 and c.sid=a.sid and a.paddr=b.addr order by value desc; 165. 如何知道监听器日志文件? 以8I为例 $ORACLE_HOME/NETWORK/LOG/LISTENER.LOG166. 如何知道监听器参数文件? 以8I为例 $ORACLE_HOME/NETWORK/ADMIN/LISTENER.ORA167. 如何知道TNS 连接文件? 以8I为例 $ORACLE_HOME/NETWORK/ADMIN/TNSNAMES.ORA168. 如何知道Sql*Net 环境文件? 以8I为例 $ORACLE_HOME/NETWORK/ADMIN/SQLNET.ORA169. 如何知道警告日志文件? 以8I为例 $ORACLE_HOME/ADMIN/SID/BDUMP/SIDALRT.LOG170. 如何知道基本结构? 以8I为例 $ORACLE_HOME/RDBMS/ADMIN/STANDARD.SQL171. 如何知道建立数据字典视图? 以8I为例 $ORACLE_HOME/RDBMS/ADMIN/CATALOG.SQL172. 如何知道建立审计用数据字典视图? 以8I为例 $ORACLE_HOME/RDBMS/ADMIN/CATAUDIT.SQL173. 如何知道建立快照用数据字典视图? 以8I为例 $ORACLE_HOME/RDBMS/ADMIN/CATSNAP.SQL ; 待续...