首页 > 代码库 > oracle public redo thread and private redo thread
oracle public redo thread and private redo thread
复习之前的学习内容，对public redo thread 和 private redo thread 的用处还是比较模糊，网上搜集的资料非常有限，看来有些好东西不跳墙是不行的。
废话少说，知识点记录下来：
在rac环境下，每个实例都有自己的redo log，这套redo log称为redo thread。这套概念同样适用于单实例数据库。
redo thread有两种，private 和 public ，在默认情况下，我们使用的是public thread。但是如果我们在创建redol log时明确指定了thread参数，那么该redo为private redo。
实验如下：
单实例：
SQL> l
1* select thread#,status,enabled from v$thread
SQL> /
THREAD# STATUS ENABLED
---------- ------ --------
1 OPEN PUBLIC
SQL> select group#,thread#,status from v$log;
GROUP# THREAD# STATUS
---------- ---------- ----------------
4 1 INACTIVE
5 1 CURRENT
SQL> col member for a60
SQL> select group#,member from v$logfile;
GROUP# MEMBER
---------- ------------------------------------------------------------
4 /home/app/oraten/oradata/oraten/redo04.log
5 /home/app/oraten/oradata/oraten/redo05.log
SQL> alter database add logfile thread 2 group 6 '/home/app/oraten/oradata/oraten/redo06.log' size 100M;
Database altered.
SQL> alter database add logfile thread 2 group 7 '/home/app/oraten/oradata/oraten/redo07.log' size 100M;
Database altered.
SQL> select thread#,status,enabled from v$thread;
THREAD# STATUS ENABLED
---------- ------ --------
1 OPEN PUBLIC
2 CLOSED DISABLED
SQL> alter database enable thread 2;
Database altered.
SQL> select thread#,status,enabled from v$thread;
THREAD# STATUS ENABLED
---------- ------ --------
1 OPEN PUBLIC
2 CLOSED PRIVATE
SQL> show parameter thread
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
parallel_threads_per_cpu integer 2
thread integer 1
SQL> alter system set thread=2 scope=spfile;
System altered.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.
Total System Global Area 281018368 bytes
Fixed Size 2095672 bytes
Variable Size 222299592 bytes
Database Buffers 50331648 bytes
Redo Buffers 6291456 bytes
Database mounted.
Database opened.
SQL> select thread#,status,enabled from v$thread;
THREAD# STATUS ENABLED
---------- ------ --------
1 CLOSED PUBLIC
2 OPEN PRIVATE
SQL> select group#,thread#,status from v$log;
GROUP# THREAD# STATUS
---------- ---------- ----------------
4 1 INACTIVE
5 1 CURRENT
6 2 CURRENT
7 2 UNUSED
SQL> Rac环境下：
[oracle@node1 ~]$ crs_stat -t -v Name Type R/RA F/FT Target State Host ---------------------------------------------------------------------- ora.easy.db application 0/0 0/1 ONLINE ONLINE node1 ora....y1.inst application 0/5 0/0 ONLINE ONLINE node1 ora....y2.inst application 0/5 0/0 ONLINE ONLINE node2 ora....SM1.asm application 0/5 0/0 ONLINE ONLINE node1 ora....E1.lsnr application 0/5 0/0 ONLINE ONLINE node1 ora.node1.gsd application 0/5 0/0 ONLINE ONLINE node1 ora.node1.ons application 0/3 0/0 ONLINE ONLINE node1 ora.node1.vip application 0/0 0/0 ONLINE ONLINE node1 ora....SM2.asm application 0/5 0/0 ONLINE ONLINE node2 ora....E2.lsnr application 0/5 0/0 ONLINE ONLINE node2 ora.node2.gsd application 0/5 0/0 ONLINE ONLINE node2 ora.node2.ons application 0/3 0/0 ONLINE ONLINE node2 ora.node2.vip application 0/0 0/0 ONLINE ONLINE node2 [oracle@node1 ~]$ [oracle@node1 ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.5.0 - Production on Sat Aug 30 17:47:08 2014 Copyright (c) 1982, 2010, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP, Data Mining and Real Application Testing options SQL> desc v$thread Name Null? Type ----------------------------------------- -------- ---------------------------- THREAD# NUMBER STATUS VARCHAR2(6) ENABLED VARCHAR2(8) GROUPS NUMBER INSTANCE VARCHAR2(80) OPEN_TIME DATE CURRENT_GROUP# NUMBER SEQUENCE# NUMBER CHECKPOINT_CHANGE# NUMBER CHECKPOINT_TIME DATE ENABLE_CHANGE# NUMBER ENABLE_TIME DATE DISABLE_CHANGE# NUMBER DISABLE_TIME DATE LAST_REDO_SEQUENCE# NUMBER LAST_REDO_BLOCK NUMBER LAST_REDO_CHANGE# NUMBER LAST_REDO_TIME DATE SQL> select thread#,status,enabled from v$thread; THREAD# STATUS ENABLED ---------- ------ -------- 1 OPEN PUBLIC 2 OPEN PUBLIC SQL> show parameter thread NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ parallel_threads_per_cpu integer 2 thread integer 1 SQL> exit Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP, Data Mining and Real Application Testing options [oracle@node1 ~]$ ssh oracle@node2 Last login: Mon Aug 25 13:09:51 2014 from node3 [oracle@node2 ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.5.0 - Production on Sat Aug 30 17:48:27 2014 Copyright (c) 1982, 2010, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP, Data Mining and Real Application Testing options SQL> show parameter thread NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ parallel_threads_per_cpu integer 2 thread integer 2 SQL> alter system set thread=1 scope=spfile sid='easy2'; System altered. SQL> alter system set thread=2 scope=spfile sid='easy1'; System altered. SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. SQL> exit Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP, Data Mining and Real Application Testing options [oracle@node2 ~]$ exit logout Connection to node2 closed. [oracle@node1 ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.5.0 - Production on Sat Aug 30 17:55:54 2014 Copyright (c) 1982, 2010, Oracle. All Rights Reserved. Connected to: Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP, Data Mining and Real Application Testing options SQL> shutdown immediate Database closed. Database dismounted. ORACLE instance shut down. SQL> startup ORACLE instance started. Total System Global Area 205520896 bytes Fixed Size 2095088 bytes Variable Size 121636880 bytes Database Buffers 75497472 bytes Redo Buffers 6291456 bytes Database mounted. Database opened. SQL> show parameter thread NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ parallel_threads_per_cpu integer 2 thread integer 2 SQL> exit Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production With the Partitioning, Real Application Clusters, OLAP, Data Mining and Real Application Testing options [oracle@node1 ~]$ ssh oracle@node2 Last login: Sat Aug 30 17:54:14 2014 from node1 [oracle@node2 ~]$ sqlplus / as sysdba SQL*Plus: Release 10.2.0.5.0 - Production on Sat Aug 30 17:57:00 2014 Copyright (c) 1982, 2010, Oracle. All Rights Reserved. Connected to an idle instance. SQL> startup ORACLE instance started. Total System Global Area 205520896 bytes Fixed Size 2095088 bytes Variable Size 100665360 bytes Database Buffers 96468992 bytes Redo Buffers 6291456 bytes Database mounted. Database opened. SQL> show parameter thread NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ parallel_threads_per_cpu integer 2 thread integer 1 SQL> desc gv$log Name Null? Type ----------------------------------------- -------- ---------------------------- INST_ID NUMBER GROUP# NUMBER THREAD# NUMBER SEQUENCE# NUMBER BYTES NUMBER MEMBERS NUMBER ARCHIVED VARCHAR2(3) STATUS VARCHAR2(16) FIRST_CHANGE# NUMBER FIRST_TIME DATE SQL> select inst_id,group#,thread# from gv$log; INST_ID GROUP# THREAD# ---------- ---------- ---------- 1 1 1 1 2 1 1 3 2 1 4 2 2 1 1 2 2 1 2 3 2 2 4 2 8 rows selected. SQL> show parameter thread NAME TYPE VALUE ------------------------------------ ----------- ------------------------------ parallel_threads_per_cpu integer 2 thread integer 1 SQL> select thread#,status,enabled from v$thread 2 ; THREAD# STATUS ENABLED ---------- ------ -------- 1 OPEN PUBLIC 2 OPEN PUBLIC SQL> alter database add logfile thread 3 group 5 '+DG4' size 50M; Database altered. SQL> alter database add logfile member '+DG4' to group 5; Database altered. SQL> alter database add logfile thread 3 group 6 '+DG4' size 50M; Database altered. SQL> alter database add logfile member '+DG4' to group 6; Database altered. SQL> alter database enable thread 3; Database altered. SQL> select thread#,status,enabled from v$thread; THREAD# STATUS ENABLED ---------- ------ -------- 1 OPEN PUBLIC 2 OPEN PUBLIC 3 CLOSED PRIVATE
结论：如果我们使用add logifle 语句时，指定的thread大于instancde_number,就会产生private thread(个人猜测),只有private thread的作用，目前尚未发现有特别的用处
oracle public redo thread and private redo thread
声明：以上内容来自用户投稿及互联网公开渠道收集整理发布，本网站不拥有所有权，未作人工编辑处理，也不承担相关法律责任，若内容有误或涉及侵权可进行投诉： 投诉/举报 工作人员会在5个工作日内联系你，一经查实，本站将立刻删除涉嫌侵权内容。