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Oracle dba interviwe p2

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               Difference between an implicit and an explicit cursor

The implicit cursor is used by Oracle server to test and parse the SQL statements and the explicit
                             cursors are declared by the programmers

.




61-What is a cursor?
Answer

A cursor is a mechanism by which you can assign a name to a “select
statement” and manipulate the information within that SQL statement.




62-What is the purpose of a cluster?
    Answer

a cluster provides an optional method of storing table data. A cluster is
comprised of a group of tables that share the same data blocks, which are
grouped together because they share common columns and are often used
together. For example, the EMP and DEPT table share the DEPTNO column.
When you cluster the EMP and DEPT, Oracle physically stores all rows for each
department from both the EMP and DEPT tables in the same data blocks. You
should not use clusters for tables that are frequently accessed individually.




63-How do you find the number of rows in a Table ?
Answer

select count(*) from table, or from NUM_ROWS column of user_tables if the table
statistics has been collected.




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64-What is a pseudo column. Give some examples?
Answer

Information such as row numbers and row descriptions are automatically stored
by Oracle and is directly accessible, ie. not through tables. This information is
contained within pseudo columns. These pseudo columns can be retrieved in
queries. These pseudo columns can be included in queries which select data
from tables.

Available Pseudo Columns
· ROWNUM - row number. Order number in which a row value is retrieved.
· ROWID - physical row (memory or disk address) location, ie. unique row
identification.
· SYSDATE - system or today’s date.
· UID - user identification number indicating the current user.
· USER - name of currently logged in user.




65-Whats is location of access_log file ?
Answer

access_log file by default is located in $IAS_ORACLE_HOME/
Apache/Apache/logs. Location of this file is defined in httpd.conf by patameter
CustomLog or TransferLog .

66-What is your Oracle Apps 11i Webserver Version and how to find it ?
Answer

From 11.5.8 to 11.5.10 Webserver version is iAS 1.0.2.2.2, In order to find
version under $IAS_ORACLE_HOME/Apache/Apache/bin execute ./httpd -
version
./httpd -version
Server version: Oracle HTTP Server Powered by Apache/1.3.19
Server built: Dec 6 2005 14:59:13 (iAS 1.0.2.2.2 rollup 5) .




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67-What is Location of Jserv configuration files ?
Answer

Jserv configuration files are located in $IAS_ORACLE_HOME /Apache/Jserv/etc




68-What is plssql/database cache ?
Answer

In order to improve performance mod_pls (Apache component) caches some
database content to file. This database/plssql cache is usually of type session
and plsql cache
# session cache is used to store session information.
# plsql cache is used to store plsql cache i.e. used by mod_pls




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69-Where is DATABASE/PLSSQL cache stored ?
Answer

PLSSQL and session cache are stored under $IAS_ORACLE_HOME/ Apache/modplsql/cache
directory.




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70-What is *.DBC file and whats is location of DBC file ?
Answer

DBC as name stands for is database connect descriptor file used to connect to database. This file
by default located in $FND_TOP/secure directory also called as $FND_SECURE directory.




71-What is content of DBC file and why its important ?
Answer

DBC file is quite important as whenever Java or any other program like forms want to connect to
database it uses DBC file. Typical entry in DBC file is
GUEST_USER_PWD
APPS_JDBC_URL
DB_HOST

72-What are few profile options which you update after cloning ?
Answer

Rapid clone updates profile options specific to site level . If you have any profile option set at
other levels like server, responsibility, user....level then reset them.




73-How to retrieve SYSADMIN password ?
Answer

If forgot password link is enabled and SYSADMIN account is configured with mail id user
forget password link else you can reset sSYSADMIN password via FNDCPASS.




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74- Whats is TWO_TASK in Oracle Database ?
Answer

TWO_TASK mocks your tns alias which you are going to use to connect to database. Lets
assume you have database client with tns alias defined as PROD to connect to Database PROD
on machine teachmeoracle.com listening on port 1521. Then usual way to connect is sqlplus
username/passwd@PROD ; now if you don't want to use @PROD then you set
TWO_TASK=PROD and then can simply use sqlplus username/passwd then sql will check that
it has to connect to tnsalias define by value PROD i.e. TWO_TASK

75- What is GWYUID ?
Answer

GWYUID , stands for Gateway User ID and password. Usually like APPLSYSPUB/PUB

76-Where GWYUID defined and what is its used in Oracle Applications ?
Answer

GWYUID is defined in dbc i.e. Database Connect Descriptor file . It is used to connect to
database by think clients.

77- If APPS_MRC schema is not used in 11.5.10 and higher then How MRC is working ?
Answer

For products like Payable, Recievables which uses MRC and if MRC is enabled then each
transaction table in base schema related to currency now has an assoicated MRC Subtables.

78-When you apply C driver patch does it require database to be Up and Why ?
Answer

Yes , database and db listener should be Up when you apply any driver patch in apps. even if
driver is not updating any database object connection is required to validate appsand other
schema and to upload patch history information in database tables.




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79-How you will avoid your query from using indexes?
Answer

By changing the order of the columns that are used in the index, in the Where condition, or by
concatenating the columns with some constant values

80-What is a OUTER JOIN?
Answer

An OUTER JOIN returns all rows that satisfy the join condition and also returns some or all of
those rows from one table for which no rows from the other satisfy the join condition.

81- Which is more faster - IN or EXISTS?

Answer

Well, the two are processed very differently.
Select * from T1 where x in ( select y from T2 )
is typically processed as:
select *
from t1, ( select distinct y from t2 ) t2
where t1.x = t2.y;

The sub query is evaluated, distinct‟ed, indexed (or hashed or sorted) and then joined to the
original table — typically. As opposed to select * from t1 where exists ( select null from t2
where y = x )

That is processed more like:
for x in ( select * from t1 )
loop
if ( exists ( select null from t2 where y = x.x )
then
OUTPUT THE RECORD
end if
end loop

It always results in a full scan of T1 whereas the first query can make use of an index on T1(x).
So, when is where exists appropriate and in appropriate? Lets say the result of the sub query (
select y from T2 ) is “huge” and takes a long time. But the table T1 is relatively small and
executing ( select null from t2 where y = x.x ) is very fast (nice index on t2(y)). Then the exists

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will be faster as the time to full scan T1 and do the index probe into T2 could be less then the
time to simply full scan T2 to build the sub query we need to distinct on.

Lets say the result of the sub query is small — then IN is typically more appropriate. If both the
sub query and the outer table are huge — either might work as well as the other — depends on
the indexes and other factors.




81- When do you use WHERE clause and when do you use HAVING clause?
Answer

The WHERE condition lets you restrict the rows selected to those that satisfy one or more
conditions. Use the HAVING clause to restrict the groups of returned rows to those groups for
which the specified condition is TRUE.

82- There is a % sign in one field of a column. What will be the query to find it?
Answer

SELECT column_name FROM table_name WHERE column_name LIKE „%\%%‟ ESCAPE ‘\’;

83-Where will you find forms configuration details apart from xml file ?
Answer

Forms configuration at time of startup is in script adfrmctl.sh and
appsweb_$CONTEXT_NAME.cfg (defined by environment variable
FORMS60_WEB_CONFIG_FILE) for forms client connection used each time a user initiates
forms connection.

84- What is forms server executable Name ?
Answer

f60srvm




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85- What are different modes of forms in which you can start Forms Server
and which one is default?
Answer

You can start forms server in SOCKET or SERVLET by defualt Forms are configured to start in
socket mode.




86-How you will start Discoverer in Oracle Apps 11i ?
Answer

In order to start dicoverer you can use script addisctl.sh under
$OAD_TOP/admin/scripts/$CONTEXT_NAME or startall.sh under
$ORACLE_HOME/discwb4/util (under Middle/Application Tier)




87-How many ORACLE HOME are Oracle Apps and whats significance of each ?
Answer

There are three $ORACLE_HOME in Oracle Apps, Two for Application Tier (Middle Tier) and
One in Database Tier.
# ORACLE_HOME 1 : On Application Tier used to store 8.0.6 techstack software. This is used
by forms, reports and discoverer. ORACLE_HOME should point to this ORACLE_HOME
which applying Apps Patch.
# ORACLE_HOME 2: On Application Tier used by iAS (Web Server) techstack software. This
is used by Web Listener and contains Apache.
# ORACLE_HOME 3: On Database Tier used by Database Software usually 8i,9i or 10g
database.




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88- Where is HTML Cache stored in Oracle Apps Server ?
Answer

Oracle HTML Cache is available at $COMMON_TOP/_pages for some previous versions you
might find it in $OA_HTML/_pages

89-Where is plssql cache stored in Oracle Apps ?
Answer

Usually two type of cache session and plssql stored under
$IAS_ORACLE_HOME/Apache/modplsql/cache

90-What happens if you don't give cache size while defining Concurrent
Manager ?
Answer

Lets first understand what is cache size in Concurrent Manager. When Manager picks request
from FND CONCURRENT REQUESTS Queues, it will pick up number of requests defined by
cache size in one shot and will work on them before going to sleep. If you don't define cache size
while defining CM then it will take default value 1, i.e. picking up one request per cycle.

91-There are lot of DBC file under $FND_SECURE, How its determined that which dbc
file to use from $FND_SECURE ?
Answer

This value is determined from profile option "Applications Database ID"

92-What is RRA/FNDFS ?
Answer

Report Review Agent(RRA) also referred by executable FNDFS is default text viewer in Oracle
Applications 11i for viewing output files and log files. As most of apps dba's are not clear about
Report Server and RRA, I'll discuss one on my blog and update link here .



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93-What is PCP is Oracle Applications 11i ?
Answer

PCP is acronym for Parallel Concurrurent processing. Usually you have one Concurrent
Manager executing your requests but if you can configure Concurrent Manager running on two
machines (Yes you need to do some additional steps in order to configure Parallel Concurrent
Processing) . So for some of your requests primary CM Node is on machine1 and secondary CM
node on machine2 and for some requests primary CM is on machine2 and secondary CM on
machine1.



94-Why I need two Concurrent Processing Nodes or in what scenarios PCP is Used ?
Answer

Well If you are running GL Month end reports or taxation reports annually these reposrts might
take couple of days. Some of these requests are very resource intensive so you can have one node
running long running , resource intensive requests while other processing your day to day short
running requets.
Another scenario is when your requests are very critical and you want high resilience for your
Concurrent Processing Node , you can configure PCP. So if node1 goes down you still have CM
node available processing your requests.




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95-Output and Logfiles for requests executed on source Instance not working on
cloned Instance ?
Answer

Here is exact problem description - You cloned an Oracle Apps Instance from PRODBOX to
another box with Instance name say CLONEBOX on 1st of August. You can any CM
logs/output files after 1st of August only becuase these all are generated on CLONEBOX itself,
But unable to view the logs/output files which are prior to 1st August. What will you do and
where to check ?
Log , Output file path and location is stored in table FND_CONCURRENT_REQUESTS. Check
select logfile_name, logfile_node_name, outfile_name, outfile_node_name from
fnd_concurrent_requests where request_id=&requestid ; where requestid is id of request for
which you are not able to see log or out files. You should see output like
/u01/PRODBOX/log/l123456.req, host1,/u01/PRODBOX/out/o123456.out, host1

Update it according to your cloned Instance Variables.




96-How to confirm if Report Server is Up and Running ?
Answer

Report Server is started by executable rwmts60 on concurrent manager Node and this file is
under $ORACLE_HOME/bin .execute command on your server like
ps -ef | grep rwmts60
You should get output like
applmgr ....... rwmts60 name=REP60_VISION

97-What is difference between ICM, Standard Managers and CRM in Concurrent Manager ?
Answer

# ICM stand for Internal Concurrent Manager, which controls other managers. If it finds other
managers down , it checks and try to restart them. You can say it as administrator to other
concurrent managers. It has other tasks as well.
# Standard Manager These are normal managers which control/action on the requests nd does
batch or single request processing. # CRM acronym for Conflict Resolution Manager is used to
resolve conflicts between managers nd request. If a request is submitted whose execution is
clashing or it is defined not to run while a particular type of request is running then such requests
are actioned/assigned to CRM for Incompatibilities and Conflict resolution
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98-What is difference between SUBSTR and INSTR?
Answer

INSTR function search string for sub-string and returns an integer indicating the position of the
character in string that is the first character of this occurrence. SUBSTR function return a portion
of string, beginning at character position, substring_length characters long. SUBSTR calculates
lengths using characters as defined by the input character set.

99- Which data type is used for storing graphics and images?

Answer

Raw, Long Raw, and BLOB.

100-What is difference between SQL and SQL*PLUS?
Answer

SQL is the query language to manipulate the data from the database. SQL*PLUS is the tool that
lets to use SQL to fetch and display the data.

101-What is difference between UNIQUE and PRIMARY KEY constraints?
Answer

An UNIQUE key can have NULL whereas PRIMARY key is always not NOT NULL. Both
bears unique values.

102- What is difference between Rename and Alias?
Answer

Rename is actually changing the name of an object whereas Alias is giving another name
(additional name) to an existing object.

Rename is a permanent name given to a table or column whereas Alias is a temporary name
given to a table or column which do not exist once the SQL statement is executed.



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103-What are various joins used while writing SUBQUERIES?

Answer

=, , IN, NOT IN, IN ANY, IN ALL, EXISTS, NOT EXISTS

104 -What is use of Apps listener ?
Answer

Apps Listener usually running on All Oracle Applications 11i Nodes with listener alias as
APPS_$SID is mainly used for listening requests for services like FNDFS and FNDSM.

105- How to start Apps listener ?
Answer

In Oracle 11i, you have script adalnctl.sh which will start your apps listener. You can also start it
by command lsnrctl start APPS_$SID (Replace sid by your Instance SID Name)

106-How to confirm if Apps Listener is Up and Running ?
Answer

execute below command
lsnrctl status APPS_$SID (replcae SID with your Instance Name)
so If your SID is VISION then use lsnrctl status APPS_VISION out put should be like
Services Summary...
FNDFS has 1 service handler(s)
FNDSM has 1 service handler(s)



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107-What is Web Listener ?
Answer

Web Listener is Web Server listener which is listening for web Services(HTTP) request. This
listener is started by adapcctl.sh and defined by directive (Listen, Port) in httpd.conf for Web
Server. When you initially type request like http://becomeappsdba.blogspot.com:80 to access
application here port number 80 is Web Listener port.

108-How will you find Invalid Objects in database ?
Answer

using query SQLPLUS> select count(*) from dba_objects where status like 'INVALID';

109- How to compile Invalid Objects in database ?
Answer

You can use adadmin utility to compile or you can use utlrp.sql script shipped with Oracle
Database to compile Invalid Database Objects

110-How to compile JSP in Oracle Apps ?
Answer

You can use ojspCompile.pl perl script shipped with Oracle apps to compile JSP files. This script
is under $JTF_TOP/admin/scripts. Sample compilation method is
perl ojspCompile.pl --compile --quiet

111-What is difference between ADPATCH and OPATCH ?
Answer

# ADPATCH is utility to apply oracle apps Patches whereas
# OPATCH is utility to apply database patches




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112-Can you use both ADPATCH and OPATCH in Apps ?
Answer

Yes you have to use both in apps , for apps patches you will use ADPATCH UTILITY and for
applying database patch in apps you will use opatch UTILITY.




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