SQL> update t set a = 1 where b = 2; -- must have redo record
2 rows updated.
SQL> rollback;
the above redo record that uncommit changed must be written from redo buffer to the online redo logfile. why Oracle write the redo record that uncommit changed to the online redo logfile ? when it will be used?
We have one primary oracle database 10.2 and standby by database with no data guard. Initially we have 2 redo log group in primary and standby database.
We have recently add 2 more redo log and increase the size of log member from 50m to 200m in primary database. We don't have any problem in primary database.but in standby database we face a problem because we cannot open it. It always in mount stage in which . How we change the size of current redo log because we can't run. Alter system switch logfile command in mount stage.
I have oracle 9i running on HP-UX, I would like to find how much redo we are generating in a given period of time, is there any script that I can use to get this information?
View 3 Replies View RelatedI learnt that logWriter writes in the redo log files when redo log buffer is 1/3 full, it means that 66 % of redo log buffer are always empty and never used,
if no, isn't a waste of memory (66 % always empty !)
I've a situation where I've very less redo logs generated. Let us say 10MB. Which solution will be better ?
1. Create one redo log group about 12 MB in size.
2. Create two redo log groups about 5 MB each in size as recommended by Oracle.
Even though solution 1 is also appropriate for me because I've less redo generated than the redo log group size. My whole redo will fit in this and I can raise checkpoint forcefully after certain period of time let us say every 3 seconds.
In one of our DB I found scenario one is implemented. So I want to know pros and cons of both of these practices.
I have some doubts about redo log files,
1) Can we fetch 'select statements' from redo log files through the use of log miner utility or any other?
(I think redo log file contains only insert,update,delete and DDL/DCL commands only)
2) If "No" to the above answer then how can i fetch all select statements fired on the system for a day or particular time.
(setting of sql_trace may be the one of them, but can it be possible for system level)
Today i noticed one problem with my database,my redologs switches in every 3mins,i also noticed there is no more transaction changes happening in database but still redo switches.
Fri Oct 05 06:10:05 2012
Thread 1 advanced to log sequence 79244
Current log# 2 seq# 79244 mem# 0: D:ORADATAORACIREDO02.LOG
Fri Oct 05 06:12:16 2012
Thread 1 advanced to log sequence 79245
Current log# 1 seq# 79245 mem# 0: D:ORADATAORACIREDO01.LOG
Fri Oct 05 06:14:28 2012
[code]......
why redo switch happening,any internal problem causes redo to switch .
redo generation. As I found the below statement in another forum."Undo segment generates the redo data also, because undo segment is database changes, so it generates the redo data also."
How a Undo segment can generate Redo and Undo datas.
Redo is getting generated very high. how to find out the reason ? database kept under 2 node cluster. chcked alert log trace and log writer trace files. pasted the content as below:
--alert log trace from node1 ( node2 also has same type of message ). Archive destination disk group - TXCOM_BACKUP_01 having enough space ( 80gb )
Mon Jan 7 00:49:10 2013
Thread 1 advanced to log sequence 448546 (LGWR switch)
Current log# 1 seq# 448546 mem# 0: +TXCOM_DATA_01/txcom/onlinelog/group_1.274.785770579
Current log# 1 seq# 448546 mem# 1: +TXCOM_DATA_01/txcom/onlinelog/group_1.302.802265189
Mon Jan 7 00:49:10 2013
[code]...
In the alert log, I am able to see the archive destination disk group ( TXCOM_BACKUP_01 ) is getting DISMOUNTED and again getting MOUNTED during every archive file generation. .
Mon Jan 7 00:49:20 2013
SUCCESS: diskgroup TXCOM_BACKUP_01 was mounted
SUCCESS: diskgroup TXCOM_BACKUP_01 was dismounted
SUCCESS: diskgroup TXCOM_BACKUP_01 was mounted
SUCCESS: diskgroup TXCOM_BACKUP_01 was dismounted
archive destination parameter in both nodes are not configured. it should read diskgroup name. ( +TXCOM_BACKUP_01 ) and corresponding size limit. Should i configure this ?
SQL> show parameter db_recovery
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
db_recovery_file_dest string
db_recovery_file_dest_size big integer 0
[code]...
should i bring the database to mount stage and set log_archive_max_proesses to high count ? now value is 2 ( default )
We had our production database hosted on Oracle 9.2.0. Few months back we have migrated it to Oracle 10.2.0.4.0. After Migration I have noticed that redo generation has become very very high. In earlier case no. of log files generating in production hours were around 30 where as after migration it become around 200 files per day. I have run statspack report on this database. Report is saying that db block change & disk write is become very high. Parameter timed_statistics has also been set to FALSE. Even then there is not any reduction on no. of log file generation. I had used import export for upgrading the databases.
View 13 Replies View RelatedWhenever any transaction happen in database redo has generated for this transaction. Do select statement treat as a transaction as it doesn't modify any thing in database. And If select statement should not be a transaction, there should not be any redo generation for select statement.
So is select statement generate redo? If yes then Why ?
understanding a redo/undo concept . Refer following data
create table t(n number);
insert into t values(10);
commit;
now I update as following
update t set n=20;
As per my understanding the before image i.e. n=10 is stored in undo (to be used for rollback, transaction recovery and even in instance recover but not in media recovery) and after image n=20 is stored in redo (to be used for various recovery purposes including media recovery in case of consistent backup).
So it is redo logs for rolling forward and undo for rolling back making transaction, db consistent . If my above understanding is true then what is meant by the term 'redo required for undo'?
Also, if there are 2 database db1 and db2 connected using database link where we are populating t1 table in db1 using t2 table in db2 using db link where redo and undo will be updated db1 or db2?
When i was starting my database .there was an error
ora-00333:redo log read error block 203 count 8192.
We are going to set up dataguard physical standby on 2-node RAC, which primary is also 2-node RAC.
PRD site: prd-node1 & prd-node2DR site: dr-node1 & dr-node2.
As I know, there is only 1 instance to do the redo apply on standby (i.e. dr-node1).
My question is, what will happen if dr-node1 failure (by shutdown abort or kill process)? will dr-node2 change to redo apply?
what's your method,when you want to change the character set ?
View 3 Replies View RelatedHow to change db timezone parameter. My application team has asked me to change the db timzone parameter by following sql.
ALTER database SET TIME_ZONE = '+10:00';
Is this way is the correct one , and do we have any impact on database and does it require a db bounce.
As per the bellow the default XML storage has been changed in 11gr2.
docs.oracle.com/cd/E11882_01/appdev.112/e10492/whatsnew.htm
Quote:
Oracle Database 11g Release 2 (11.2.0.2) New Features in Oracle XML DB
The following Oracle XML DB features are new in Oracle Database 11g Release 2 (11.2.0.2).
Default Storage Model for XMLType
The default XMLType storage model is used if you do not specify a storage model when you create an XMLType table or column. Prior to Oracle Database 11g Release 2 (11.2.0.2), unstructured (CLOB) storage was used by default. The default storage model is now binary XML storage.
We have a application which works fine on r1 but not on r2 due to this change, we are going to investigate resolving the issue on the application in the future, in the mean time we need to be able to use the CLOB storage.
Does any one know where we can change this functionality back to the pre 11gR2 change?
Currently my oracle database character set is we8mswin1252 and it is only containing English data as well as spatial data (which is in English of course). I would like to change the Database character set so it could accept Arabic characters.
I have checked the below command on a test DB and it worked fine, but I want to know if it's recommended as a best practice when changing the character set to accept arabic and this won't corrupt my old entered Data ?
SHUTDOWN IMMEDIATE
STARTUP RESTRICT
ALTER DATABASE CHARACTER SET INTERNAL_USE AR8MSWIN1256
SHUTDOWN IMMEDIATE
STARTUP
When I created a new oracle database the port number was 1521 (default), but I want to change it to 1522.
View 4 Replies View Relatedi have a oracle server installed enterprise edition, for some reation i need to degrade the version from enterprise to standard
i need same tablespace,data's everything same as of now.
I can not change the parameters RESOURCE_MANAGER_PLAN, at first, I set the parameters to DAYTIME,but when I restart my db,the parameters hold old values named MAXCAP_PLAN. Why?
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0 - Production
PL/SQL Release 11.2.0.1.0 - Production
CORE 11.2.0.1.0 Production
TNS for 32-bit Windows: Version 11.2.0.1.0 - Production
NLSRTL Version 11.2.0.1.0 - Production
[code]....
Which config file is used to change the os version(RHEL 4.0 to RHEL 5.5) by OS admin what will be its impact on ORACLE Databases.
View 3 Replies View RelatedWhat is best practice to change small disk D:? I am beginner with Oracle. 10g on W2008. 5 datafiles (all indexes,second data file, 2 undotabs)*.dbf (34;30;1;34;12 GB) is on D:. Part of tablespaces (1 data, 1 undo)has files on c:.
I.
1.Shutdown 2008 server.
2.Copy D: image with GHOST to USB, network.
3.Connect new D, create RAID.
4.Restore image to D.
5.Start 2008 server.
II.
1.Stop application.
2.CONNECT AS SYSDBA
3.SHUTDOWN NORMAL or (IMMEDIATE)?
4.Copy files *.dbf at OS level from d: to ... USB disk, network.
5.Shutdown 2008 server.
6.Change disks, create RAID in BIOS.
7.Start W2008.
Is Oracle at this moment in SHUTDOWN mode?
8.Copy back *.dbf to new D: (with directory structure).
9.STARTUP Oracle.
When I was going through the Enterprise Manager Grid Control, I found an error due to which I looked at the trace file and it said:
ORA-07445: exception encountered: core dump ACCESS_VIOLATION unable_to_trans_pc PC:0x7C81BD02 ADDR:0x49444E49 UNABLE_TO_READ]
I searched and found that it has something to do with the SGA parameters. I saw that the shared_pool_size and the sga_target paramters are set to 0...Also there are certain SQLs hanging at some point. I thought I should change the above mentioned parameters.
My question now is, can I use the Alter System statements from the SQL Plus to change these parameters, and do they change immediately or do I need to reboot the Oracle instance for those changes to take effect? I would like to do:
alter system set sga_target=400m;
alter system set shared_pool_size=200m;
would these work and take effect immediately?
This facility has one last 10g database and a very problematic tablespace and last datafile associated with it. The tablespace was set up with INITIAL_ EXTENT of 131,072 (128K) instead of the more 'normal' 4,194,304 (4M) and NEXT_EXTENT of 262,144 (256K) instead of 4,194,304 (4M).
More worryingly, the datafile has INCREMENT_BY set to 1 (8K) instead of 1,280 (10M) or 2,048 (16M).Has anyone ever updated sys.ts$.dflinit and sys.ts$. dflincr to modify the INITIAL_EXTENT and NEXT_EXTENT, and sys.file$.inc to modify the INCREMENT_BY?
1-how can i alter/change the size of tablespaces?.
2-is any changing in tablespace size will effect the over all performance?
Tablespace ; Size (MB); Free (MB); % Free; % Used
------------------------------;----------;----------;----------;----------
USERS ; 5; 4; 80; 20
SYSAUX ; 600; 140.875; 23; 77
UNDOTBS1 ; 640; 114.125; 18; 82
SYSTEM ; 700; 28.3125; 4; 96
TEMP ; 64; 0; 0; 100
While renaming the datafile.
1) ALTER TABLESPACE .... OFFLINE;
2) CHANGING THE DATAFILE NAME IN OS LEVEL;
3) ALTER TABLESPACE .... RENAME DATAFILE 'FILE_OLD' TO 'FILE_NEW';
4) ALTER TABLESPACE .... ONLINE;
In the above steps, I HAD FORGOTTON TO FOLLOW THE 2ND STEP.
At the step of 3rd, i got error message, now i am not able to change the name in OS level Also.
I want to change cursor_sharing, open_cursors and session_cached_cursors parameter values for SPFILE (Only SPFILE) using SQL Query.
I have found following SQL Queries, but I don't know these queries are only for SPFILE or not.
ALTER SESSION SET cursor_sharing='EXACT';
ALTER system set open_cursors=2500;
ALTER SESSION set session_cached_cursors=70;
I need SQL Queries only for SPFILE.
How to change Character set for oracle 8i database. Is there anyway to change the Character set without affecting the current database.
View 11 Replies View RelatedI am currently in the process of migrating our database from US7ASCII to AL32UTF8 using DMU.
I am stuck at a point where I have encrypted data that, when the conversion happens, will be destroyed. Oracle suggests to move the data which is currently stored in VARCHAR2 datatype, to a "character set safe way" like hex notation or base64 before converting.