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What is a deadlock ? Explain .
Two processes wating to update the rows of a table which are locked by the other process then deadlock arises. In a database environment this will often happen because of not issuing proper row lock commands. Poor design of front-end application may cause this situation and the performance of server will reduce drastically. These locks...
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What is the difference between Pctused and PctFree?
dinesh1909
- Nov 19th, 2007
Consider 8K block size. The total bytes 8 x 1024 = 8196 bytesEach block requires approximately 117 bytes for the header. Please note that the header size varies depending upon the block size. The tota...
C.Ramesh
- Nov 16th, 2007
PCT USERD - The Percentage of Minimum space user for insertion of New Row data. The value determines when the block gets into the FREELISTS structurePCTFREE - The Percentage of Space reserved for future updation of existing dataC.Ramesh
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What is directory naming in oracle9i ?
pradeesh04
- Dec 7th, 2007
Oracle Net Services use a centralized directory server as one of the primary methods for storage of connect identifiers. Clients configured directory usage can use the connect identifiers in the...
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Index tablespace for a Database
How to assign an index tablespace for a database permanently, so that whatever indexes we are creating in the database, should automatically goes to that tablespace i.e. we neednot supply the tablespace name during index creation.
kailasTile
- Dec 17th, 2007
There is no such provision in oracle to have default index tablespace. Workaround is- you can have a job which will scan for indexes in other tablespaces and rebuild into desired one.
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How to manager Memory in Oracle Database? How to maximize nos. of user in Oracle Database?
kailasTile
- Dec 17th, 2007
It depends on your requirement, if you want no of users around 300 then you can still achieve that by keeping PGA parameters low. If you are looking for number of users 1000 or even more, you need to go for shared server mode.
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Is VARCHAR2 size optimization worthwhile ?
Hi, I've recently commissioned a hosted system from a developer who has recommended using J2EE and Oracle. Their J2EE system is quite slick and works very well in preproduction. It uses annotations to generate the Oracle tables on the fly during deployment. On examination of the table structures that it's generated though, it's defaulted all of the VARCHAR2 definitions to 255 characters. On asking...
kailasTile
- Dec 18th, 2007
Changing VARCHAR2(255) to precise required width is good table design. Though it will not improve performance as such.
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Cloning and Standby Databases
What is the difference between Cloning and Standby databases?
rajendra_thanekar
- Jan 2nd, 2008
Cloning is nothing but the copy of your database which can be open in read write mode. The standby database is also a copy of your database which is in standby mode and which is made in sink with prod...
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What is difference between base table and data dictionary views?
kunal1017
- Jan 10th, 2008
HiBase tables are made when the database is created and these tables are stored in data dictionary. these base tables contains the information related to the database.? these tables are own by sys.th...
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What is the difference between materialized view and snapshots
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Installing Oracle9i/10g at unix (RedHat) environment
While Installing Oracle9i/10g at unix (RedHat) environment , which parameter needs to be set at OS level, to login as a sysdba in Oracle for the first time?
skpanuganti
- Feb 8th, 2008
.bash_profile has to set at OS level before connecting to oracle database.
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Explain about Oracle Statistics parameter in export?
ramanava1
- Feb 22nd, 2008
Export is one of taking backup. In export backup you can specify many parameters in par file or at command line. One of the parameter is statistics=y or n. If you specify y it is going to export statistics generated in the database placed in dump file.
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How can the problem be resolved if a SYSDBA, forgets his password for logging into enterprise manager?
mhans
- Feb 25th, 2008
1. Always you should have one more user activated as SYSDBA and this is achieved by using orapw utility2. If there is just one SYS user then on unix platform, login as ORACLE user (DBA group)3. sqlplus '/ as sysdba'alter user sys identified by 'xyz' ;This would change SYS pwd
senthilora
- Sep 24th, 2007
I think there are 2 ways to do that.1. Login as SYSTEM and change the SYS password by using ALTER USER.2. Recreate the password file using orapwd and set remote_password_file=exclusive and then restart the instance.
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Cache Fusion Technology
What is Cache Fusion Technology?
bhuvannpg
- Feb 28th, 2008
Cache Fusion is a new technology that uses a high speed interprocess communication (IPC) interconnect to provide cache to cache transfers of data blocks between instances in a cluster. This eliminates...
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Flash Back Query
What is a flash back query? This feature is also available in 9i. whats the difference between 9i and 10g (related to flash back query).
hemant.agarwal03
- Mar 12th, 2008
Oracle 10g offers significant enhancements that help insure the high availability of any Oracle database, as well as improvements in the database disaster recovery arena. This paper explores one of th...
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DBMS_meta_data Parameter
DBMS_meta_data. This parameter is very usefull. What you infer from this parameter. What info you will find in that. explain in detail.
hemant.agarwal03
- Mar 12th, 2008
To find the structure of a external table we used this package.syntax is below:SELECT DBMS_METADATA.GET_DDL ('TABLE','<Table Name in CAPS>')||';' FROM DUAL
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Standby Databases
What is standby databases? Difference between Physical and logical standby databases
rajendra_thanekar
- Mar 14th, 2008
A standby database is a transactionally consistent copy of the primary database. Using a backup copy of the primary database, you can create up to nine standby databases.A standby database can be eith...
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Datafile Size
What is your datafile size? How long it can go? What is the max limit to which you can extend?
hemant.agarwal03
- Mar 18th, 2008
v$datafile data dictionary view will tell us the size of a datafile.to check the number of datafile you can check db_files init parameter. you can also alter this parameter but it will reflect after restartthe database.you can also resize the datafile size.
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Compression Parameter
You have a database of 2GB. Can you convert the database to 1GB. Which compression parameter will you use?
hemant.agarwal03
- Mar 18th, 2008
COMPRESSION =(METADATA_ONLY | NONE) - This parameter applies from Oracle 10.2. It specifies whether to compress metadata before writing to the dump file set. Compression reduces the amount of disk spa...
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Overcome Alert Log Error
Show one instance when you encountered an error in alert log and you overcome that error. What actions you took to overcome that error.
rajendra_thanekar
- Mar 24th, 2008
Hi,Oracle write error in alert log file. Depending upon the error corrective action needs to be taken.1) DeadLock Error : Take the trace file in user dump destination and analysis it for the error.2) ...
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Difference between failover and switch over servers
kailasTile
- Mar 27th, 2008
Failover: Primary fails and standby is made primary.Switchover: Primary and secondary interchanges the role.Effectively, in both cases, standby becomes primary, main difference is, when failover happe...
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