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What is an index and How it is implemented in Oracle database
harshasp
- Jul 16th, 2008
Index is an object in the oracle database used to speed up the performance of the queries ie. it improves the access speed and response of query will be good when the query makes use of Index.ThanksHarsha
ramesh khanna
- Jun 27th, 2005
Index is a object to fetch the data fast and where class in the sql can be used to use the index
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Execute Analyze Table Command
In which situation whether peak time or off peak time you will execute the ANALYZE TABLE command. Why?
harisivati
- Jul 13th, 2008
Gathering statistics can be very resource intensive for the server so avoid peak workload times to gather stale stats or Analyze Table .
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Schema Procedure and Data
Schema A has some objects and created one procedure and granted to Schema B. Schema B has the same objects like Schema A. Schema B executed the procedure like inserting some records. In this case where the data will be stored whether in Schema A or Schema B?
shuklad
- Jul 6th, 2008
Procedure will be executed with the authority of A and therfore data will go to the tables owned by A. If one wants the data to go to B, use the clause authid current_user while defining the procedure.
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What is row chaining
deepikadba
- Jun 7th, 2008
If a datablock is not able to store a complete row due to its less size then a row is store in another blocks & address of that row is stored in the previous block.it degrade performance of a database & there r more IOS generated.
sandhya
- Jun 27th, 2005
If any of he empty row is not sufficient to hold the row. then row is placed in multiple blocks. it happenes when the block size is small and rows are of large size. then it cause chaining. Due to chaining performance degrades and will cause more IOs
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Oratab file
What is stored in Oratab file
mandarkelkar
- Jun 5th, 2008
This file is used by ORACLE utilities. It is created by root.sh and updated by the Database Configuration Assistant when creating a database.A colon, ':', is used as the field terminator...
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Oracle Table space used and unused space
I have to check used space/unused space in table space. Which view /command will provide me the desired answer.
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How to know which query is taking long time?
pabroy
- May 5th, 2008
You can search Top ten sql.Top 10 Sql. SELECT *FROM (SELECT rownum,Substr(a.sql_text,1,200) sql_text, Trunc(a.disk_reads/Decode(a.executions,...
senthilora
- Sep 24th, 2007
You can use STATSPACK to take SNAPs while running those queries and get the report with details of SQLs taking more time to respond.
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Oracle Snapshot too old error
What is Ora1555 error. Snapshot too Old error. Explain in detail.
jryan999
- May 1st, 2008
Oracle Rollback Segments (Undo more recently) hold a copy of data before it was modified, and they work in a round-robin fashion. Writing and then eventually overwriting the entries as soon as...
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DBMS v/s RDBMS
Discuss the advantages and disadvantages of hierarchical database management system in comparison with RDBMS. Discuss types of applications suitable for hierarchical DBMS and RDBMS.
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Changes in Database buffer cache
What are the changes that happen in Database buffer cache(List of all changes in DB Buffer Cache)
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Disk (sort) Ratio
The ratio of disk (sort) is high. Is that good or bad? Why? How will you reduce disk sort?
rajendra_thanekar
- Apr 17th, 2008
Hi,Disk(sort)ratio is high is not good.Please set sort_area_retained_size and sort_area_size so that session can sort in max in memory.
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Determine Number of Blocks Corrupted
You have a database. You have a datafile and some blocks are corrupted in the datafile. What statement will you issue to know how many blocks are corrupted?
kunal1017
- Apr 1st, 2008
you can use the DBVERIFY utility to check the corruption in datafiles so that you can now number of blocks corrupted.Here is the procedure :On o/s prompt login as oracle user : $ dbv file= &...
hemant.agarwal03
- Mar 12th, 2008
You can check the "V_$DATABASE_BLOCK_CORRUPTION" view to determine the corrupted blocks.
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Difference between failover and switch over servers
kailasTile
- Mar 27th, 2008
Failover: Primary fails and standby is made primary.Switchover: Primary and secondary interchanges the role.Effectively, in both cases, standby becomes primary, main difference is, when failover happe...
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Overcome Alert Log Error
Show one instance when you encountered an error in alert log and you overcome that error. What actions you took to overcome that error.
rajendra_thanekar
- Mar 24th, 2008
Hi,Oracle write error in alert log file. Depending upon the error corrective action needs to be taken.1) DeadLock Error : Take the trace file in user dump destination and analysis it for the error.2) ...
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Compression Parameter
You have a database of 2GB. Can you convert the database to 1GB. Which compression parameter will you use?
hemant.agarwal03
- Mar 18th, 2008
COMPRESSION =(METADATA_ONLY | NONE) - This parameter applies from Oracle 10.2. It specifies whether to compress metadata before writing to the dump file set. Compression reduces the amount of disk spa...
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Datafile Size
What is your datafile size? How long it can go? What is the max limit to which you can extend?
hemant.agarwal03
- Mar 18th, 2008
v$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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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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Export Query
How to write script for export backup in shell.
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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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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...
Oracle DBA Interview Questions
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