Sunday, July 22, 2012

Oracle DBA Interview questions


Differentiate between TRUNCATE and DELETE.
The Delete command will log the data changes in the log file where as the truncate will simply remove the data without it. Hence Data removed by Delete command can be rolled back but not the data removed by TRUNCATE. Truncate is a DDL statement whereas DELETE is a DML statement.

What is the maximum buffer size that can be specified using the DBMS_OUTPUT.ENABLE function?
1000000

Can you use a commit statement within a database trigger?
Yes, if you are using autonomous transactions in the Database triggers.

What is an UTL_FILE? What are different procedures and functions associated with it?
The UTL_FILE package lets your PL/SQL programs read and write operating system (OS) text files. It provides a restricted version of standard OS stream file input/output (I/O).
Subprogram -Description
FOPEN function-Opens a file for input or output with the default line size.
IS_OPEN function -Determines if a file handle refers to an open file.
FCLOSE procedure -Closes a file.
FCLOSE_ALL procedure -Closes all open file handles.
GET_LINE procedure -Reads a line of text from an open file.
PUT procedure-Writes a line to a file. This does not append a line terminator.
NEW_LINE procedure-Writes one or more OS-specific line terminators to a file.
PUT_LINE procedure -Writes a line to a file. This appends an OS-specific line terminator.
PUTF procedure -A PUT procedure with formatting.
FFLUSH procedure-Physically writes all pending output to a file.
FOPEN function -Opens a file with the maximum line size specified.


Difference between database triggers and form triggers?
Database triggers are fired whenever any database action like INSERT, UPATE, DELETE, LOGON LOGOFF etc occurs. Form triggers on the other hand are fired in response to any event that takes place while working with the forms, say like navigating from one field to another or one block to another and so on.

What is OCI. What are its uses?
OCI is Oracle Call Interface. When applications developers demand the most powerful interface to the Oracle Database Server, they call upon the Oracle Call Interface (OCI). OCI provides the most comprehensive access to all of the Oracle Database functionality. The newest performance, scalability, and security features appear first in the OCI API. If you write applications for the Oracle Database, you likely already depend on OCI. Some types of applications that depend upon OCI are:

· PL/SQL applications executing SQL
· C++ applications using OCCI
· Java applications using the OCI-based JDBC driver
· C applications using the ODBC driver
· VB applications using the OLEDB driver
· Pro*C applications
· Distributed SQL


What are ORACLE PRECOMPILERS?
A precompiler is a tool that allows programmers to embed SQL statements in high-level source programs like C, C++, COBOL, etc. The precompiler accepts the source program as input, translates the embedded SQL statements into standard Oracle runtime library calls, and generates a modified source program that one can compile, link, and execute in the usual way. Examples are the Pro*C Precompiler for C, Pro*Cobol for Cobol, SQLJ for Java etc.

What is syntax for dropping a procedure and a function? Are these operations possible?
Drop Procedure/Function ; yes, if they are standalone procedures or functions. If they are a part of a package then one have to remove it from the package definition and body and recompile the package.
How to check if Apps 11i System is Autoconfig enabled ?
Under $AD_TOP/bin check for file adcfginfo.sh and if this exists use adcfginfo.sh contextfile=<CONTEXT> show=enabled

If this file is not there , look for any configuration file under APPL_TOP if system is Autoconfig enabled then you will see entry like


How to check if Oracle Apps 11i System is Rapid Clone enabled ?
For syetem to be Rapid Clone enabled , it should be Autoconfig enabled (Check above How to confirm if Apps 11i is Autoconfig enabled). You should have Rapid Clone Patches applied , Rapid Clone is part of Rapid Install Product whose Family Pack Name is ADX. By default all Apps 11i Instances 11.5.9 and above are Autoconfig and Rapid Clone enabled.

Whats is difference between two env files in <CONTEXT>.env and APPS<CONTEXT>.env under $APPL_TOP ?
APPS<CONTEXT>.env is main environment file which inturn calls other environment files like <CONTEXT>.env under $APPL_TOP, <CONTEXT>.env under 806 ORACLE_HOME and custom.env for any Customized environment files.

Whats main concurrent Manager types.
# ICM - Internal Concurrent Manager which manages concurrent Managers
# Standard Managers - Which Manage processesing of requests.
# CRM - Conflict Resolution Managers , resolve conflicts in case of incompatibility.


Whats US directory in $AD_TOP or under various product TOP's .
US directory is defauly language directory in Oracle Applications. If you have multiple languages Installed in your Applications then you will see other languages directories besides US, that directory will contain reports, fmx and other code in that respective directory like FR for France, AR for arabic, simplifies chinese or spanish.

Where is Concurrent Manager log file location.
By default standard location is $APPLCSF/$APPLLOG , in some cases it can go to $FND_TOP/log as well.

Where would i find .rf9 file, and what execatly it dose ?
These files are used during restart of patch in case of patch failure because of some reason.

Where is appsweb.cfg or appsweb_$CONTEXT.cfg stored and why its used ?
This file is defined by environment variable FORMS60_WEB_CONFIG_FILE This is usually in directory $OA_HTML/bin on forms tier.

This file is used by any forms client session. When a user try to access forms , f60webmx picks up this file and based on this configuration file creates a forms session to user/client.


What is Multi Node System ?
Multi Node System in Oracle Applications 11i means you have Applications 11i Component on more than one system. Typical example is Database, Concurrent Manager on one machine and forms, Web Server on second machine is example of Two Node System.
Can a function take OUT parameters. If not why?
yes, IN, OUT or IN OUT.

Can the default values be assigned to actual parameters?
Yes. In such case you don’t need to specify any value and the actual parameter will take the default value provided in the function definition.

What is difference between a formal and an actual parameter?
The formal parameters are the names that are declared in the parameter list of the header of a module. The actual parameters are the values or expressions placed in the parameter list of the actual call to the module.

What are different modes of parameters used in functions and procedures?
There are three different modes of parameters: IN, OUT, and IN OUT.

IN - The IN parameter allows you to pass values in to the module, but will not pass anything out of the module and back to the calling PL/SQL block. In other words, for the purposes of the program, its IN parameters function like constants. Just like constants, the value of the formal IN parameter cannot be changed within the program. You cannot assign values to the IN parameter or in any other way modify its value.

IN is the default mode for parameters. IN parameters can be given default values in the program header.

OUT - An OUT parameter is the opposite of the IN parameter. Use the OUT parameter to pass a value back from the program to the calling PL/SQL block. An OUT parameter is like the return value for a function, but it appears in the parameter list and you can, of course, have as many OUT parameters as you like.

Inside the program, an OUT parameter acts like a variable that has not been initialised. In fact, the OUT parameter has no value at all until the program terminates successfully (without raising an exception, that is). During the execution of the program, any assignments to an OUT parameter are actually made to an internal copy of the OUT parameter. When the program terminates successfully and returns control to the calling block, the value in that local copy is then transferred to the actual OUT parameter. That value is then available in the calling PL/SQL block.

IN OUT - With an IN OUT parameter, you can pass values into the program and return a value back to the calling program (either the original, unchanged value or a new value set within the program). The IN OUT parameter shares two restrictions with the OUT parameter:

An IN OUT parameter cannot have a default value.

An IN OUT actual parameter or argument must be a variable. It cannot be a constant, literal, or expression, since these formats do not provide a receptacle in which PL/SQL can place the outgoing value.


Difference between procedure and function.
A function always returns a value, while a procedure does not. When you call a function you must always assign its value to a variable.

Can cursor variables be stored in PL/SQL tables. If yes how. If not why?
Yes. Create a cursor type - REF CURSOR and declare a cursor variable of that type.
DECLARE
/* Create the cursor type. */
TYPE company_curtype IS REF CURSOR RETURN company%ROWTYPE;

/* Declare a cursor variable of that type. */
company_curvar company_curtype;

/* Declare a record with same structure as cursor variable. */
company_rec company%ROWTYPE;
BEGIN
/* Open the cursor variable, associating with it a SQL statement. */
OPEN company_curvar FOR SELECT * FROM company;

/* Fetch from the cursor variable. */
FETCH company_curvar INTO company_rec;

/* Close the cursor object associated with variable. */
CLOSE company_curvar;
END;

Can you clone from multi node system to single node system and vice versa ?
Yes , this is now supported via Rapid Clone, Check if your system has all prereq. patches for Rapid Clone and you are on latest rapid clone patch.

Does rapid clone takes care of Updating Global oraInventory or you have to register manually in Global OraInventory after clone ?
Rapid Clone will automatically Update Global oraInventory during configuration phase. You don't have to do any thing manually for Global oraInventory.

What is .dbc file , where its stored , whats use of .dbc file ?
dbc as name says is database connect descriptor file which stores database connection information used by application tier to connect to database. This file is in directory $FND_TOP/secure also called as FND_SECURE

Whats things you do to reduce patch timing ?
You can take advantage of following -
# Merging patches via admrgpch
# Use various adpatch options like nocompiledb or nocompilejsp
# Use defaults file
# Staged APPL_TOP during upgrades
# Increase batch size (Might result into negative )


How you put Applications 11i in Maintenance mode ?
Use adadmin to change Maintenance mode is Oracle Apps. With AD.I you need to enable maintenance mode in order to apply apps patch via adpatch utility. If you don't want to put apps in maintenance mode you can use adpatch options=hotpatch feature.

Can you apply patch without putting Applications 11i in Maintenance mode ?
Yes, use options=hotpatch as mentioned above with adpatch.

What are various options available with adpatch ?
Various options available with adpatch depending on your AD version are autoconfig, check_exclusive, checkfile, compiledb, compilejsp, copyportion, databaseprtion, generateportion, hotpatch, integrity, maintainmrc, parallel, prereq, validate

ADIDENT UTILITY is used for what ?
ADIDENT UTILITY in oracle apps is used to find version of any file . AD Identification. for ex. "adident Header <filename> 

How do you pass cursor variables in PL/SQL?
Pass a cursor variable as an argument to a procedure or function. You can, in essence, share the results of a cursor by passing the reference to that result set.

How do you open and close a cursor variable. Why it is required?
Using OPEN cursor_name and CLOSE cursor_name commands. The cursor must be opened before using it in order to fetch the result set of the query it is associated with. The cursor needs to be closed so as to release resources earlier than end of transaction, or to free up the cursor variable to be opened again.

What should be the return type for a cursor variable. Can we use a scalar data type as return type?
The return type of a cursor variable can be %ROWTYPE or record_name%TYPE or a record type or a ref cursor type. A scalar data type like number or varchar can’t be used but a record type may evaluate to a scalar value.

What is use of a cursor variable? How it is defined?
Cursor variable is used to mark a work area where Oracle stores a multi-row query output for processing. It is like a pointer in C or Pascal. Because it is a TYPE, it is defined as TYPE REF CURSOR RETURN ;

What WHERE CURRENT OF clause does in a cursor?
The Where Current Of statement allows you to update or delete the record that was last fetched by the cursor.

Difference between NO DATA FOUND and %NOTFOUND
NO DATA FOUND is an exception which is raised when either an implicit query returns no data, or you attempt to reference a row in the PL/SQL table which is not yet defined. SQL%NOTFOUND, is a BOOLEAN attribute indicating whether the recent SQL statement does not match to any row.

What is a cursor for loop?
A cursor FOR loop is a loop that is associated with (actually defined by) an explicit cursor or a SELECT statement incorporated directly within the loop boundary. Use the cursor FOR loop whenever (and only if) you need to fetch and process each and every record from a cursor, which is a high percentage of the time with cursors.

What is iAS Patch ?
iAS Patch are patches released to fix bugs associated with IAS_ORACLE_HOME (Web Server Component) Usually these are shiiped as Shell scripts and you apply iAS patches by executing Shell script. Note that by default ORACLE_HOME is pointing to 8.0.6 ORACLE_HOME and if you are applying iAS patch export ORACLE_HOME to iAS . You can do same by executing environment file under $IAS_ORACLE_HOME

If we run autoconfig which files will get effected ?
In order to check list of files changes during Autoconfig , you can run adchkcfg utility which will generate HTML report. This report will list all files and profile options going to change when you run AutoConfig.

What is difference between .xml file and AutoConfig ?
Autoconfig is Utility to configure your Oracle Application environment. .xml file is repository of all configuration from which AutoConfig picks configuration and polulates related files.

What is .lgi files ?
lgi files are created with patching along with .log files . .lgi files are informative log files containing information related to patch. You can check .lgi files to see what activities patch has done. Usually informative logs.

How will you skip worker during patch ?
If in your adctrl there are six option shown then seventh is hidden option.(If there are seven options visible then 8th option is to Skip worker depending on ad version).

Which two tables created at start of Apps Patch and drops at end of Patch ?
FND_INSTALLED_PROCESS and AD_DEFFERED_JOBS are the tables that get updated while applying a patch mainly d or unified driver.

How to compile an Oracle Reports file ?
Utility adrepgen is used to compile Reports. Synatx is given below adrepgen userid=apps\<psswd> source = $PRODUCT_TOP\srw\filename.rdf dest=$PRODUCT_TOP\srw\filename.rdf stype=rdffile dtype=rdffile logfile=x.log overwrite=yes batch=yes dunit=character

What is difference between AD_BUGS and AD_APPLID_PATCHES ?
AD_BUGS holds information about the various Oracle Applications bugs whose fixes have been applied (ie. patched) in the Oracle Applications installation.

AD_APPLIED_PATCHES holds information about the "distinct" Oracle Applications patches that have been applied. If 2 patches happen to have the same name but are different in content (eg. "merged" patches), then they are considered distinct and this table will therefore hold 2 records.

What is ADSPLICE UTILITY ?
ADSPLICE UTILITY in oracle apps is utility to add a new product.

How can you licence a product after installation ?
You can use ad utility adlicmgr to licence product in Oracle Apps.

What is MRC ? What you do as Apps DBA for MRC ?
MRC also called as Multiple Reporting Currency in oracle Apps. Default you have currency in US Dollars but if your organization operating books are in other currency then you as apps dba need to enable MRC in Apps. How to enable MRC coming soon...

What is access_log in apache , what entries are recored in access_log ? Where is default location of thsi file ?
access_log in Oracle Application Server records all users accessing oracle applications 11i. This file location is defined in httpd.conf with default location at $IAS_ORACLE_HOME/Apache/Apache/logs. Entries in this file is defined by directive LogFormat in httpd.conf Typical entry in access_log is
198.0.0.1 - - [10/Sep/2006:18:37:17 +0100] "POST /OA_HTML/OA.jsp?.... HTTP/1.1" 200 28035
where 200 is HTTP status code and last digits 28035 is bytes dowloaded as this page(Size of page)


Where is Jserv configuration files stored ?
Jserv configuration files are stored in $IAS_ORACLE_HOME/Apache/Jserv/etc

Where is applications start/stop scripts stored ?
applications start/stop scripts are in directory $COMMON_TOP/admin/scripts/$CONTEXT_NAME

What are main configuration files in Web Server (Apache) ?
Main configuration files in Oracle Apps Web Server are
# httpd.conf, apps.conf, oracle_apache.conf, httpd_pls.conf
# jserv.conf, ssp_init.txt, jserv.properties, zone.properties
# plsql.conf, wdbsvr.app, plsql.conf


Can C driver in apps patch create Invalid Object in database ?
No , C driver only copies files in File System. Database Object might be invalidated during D driver when these objects are created/dropped/modified.

What is dev60cgi and f60cgi ?
CGI stands for Common Gateway Interface and these are Script Alias in Oracle Apps used to access forms server . Usually Form Server access directly via http://hostname:port/dev60cgi/f60cgi

Why does a worker fails in Oracle Apps Patch and few scenarios in which it failed for you ?
Apps Patch worker can fail in case it doesn't find expected data, object, files or any thing which driver is trying to update/edit/modify. Possible symptoms may be underlying tables/objects are invalid, a prereq patch is missing , login information is incorrect, inconsistency in seeded data...

What is difference between mod_osso and mod_ose in Oracle HTTP Server ?
mod_osso is Oracle Single Sign-On Module where as mod_ose is module for Oracle Servlet Engine.
mod_osso is module in Oracle's HTTP Server serves as Conduit between Oracle Apache Server and Singl Sign-On Server where as mod_ose is also another module in Oracle's HTTP Server serves as conduit between Oracle Apache and Oracle Servlet Engine.


What is difference between COMPILE_ALL=SPECIAL and COMPILE=ALL while compiling Forms ?
Both the options will compile all the PL/SQL in the resultant .FMX, .PLX, or .MMX file but COMPILE_ALL=YES also changes the cached version in the source .FMB, .PLL, or .MMB file. This confuses version control and build tools (CVS, Subversion, make, scons); they believe you've made significant changes to the source. COMPILE_ALL=SPECIAL does not do this.

What is GSM in Oracle application E-Business Suite ?
GSM stands for Generic Service Management Framework. Oracle E-Business Suite consist of various compoennts like Forms, Reports, Web Server, Workflow, Concurrent Manager ..

Earlier each service used to start at their own but managing these services (given that) they can be on various machines distributed across network. So Generic Service Management is extension of Concurrent Processing which manages all your services , provide fault tolerance (If some service is down ICM through FNDSM and other processes will try to start it even on remote server) With GSM all services are centrally managed via this Framework.


What is FNDSM ?
FNDSM is executable and core component in GSM ( Generic Service Management Framework discussed above). You start FNDSM services via APPS listener on all Nodes in Application Tier in E-Business Suite.

What are cursor attributes?
Cursor attributes are used to get the information about the current status of your cursor. Both explicit and implicit cursors have four attributes, as shown:
Name Description
%FOUND Returns TRUE if record was fetched successfully, FALSE otherwise.
%NOTFOUND Returns TRUE if record was not fetched successfully, FALSE otherwise.
%ROWCOUNT Returns number of records fetched from cursor at that point in time.
%ISOPEN Returns TRUE if cursor is open, FALSE otherwise.


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.

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

What is the purpose of a cluster?
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.

How do you find the number of rows in a Table ?
select count(*) from table, or from NUM_ROWS column of user_tables if the table statistics has been collected.

Display the number value in Words?

What is a pseudo column. Give some examples?
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.


Whats is location of access_log file ?
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

What is your Oracle Apps 11i Webserver Version and how to find it ?
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)


What is Location of Jserv configuration files ?
Jserv configuration files are located in $IAS_ORACLE_HOME /Apache/Jserv/etc .

What is plssql/database cache ?
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


Where is DATABASE/PLSSQL cache stored ?
PLSSQL and session cache are stored under $IAS_ORACLE_HOME/ Apache/modplsql/cache directory.

What is *.DBC file and whats is location of DBC file ?
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.

What is content of DBC file and why its important ?
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


What are few profile options which you update after cloning ?
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.

How to retrieve SYSADMIN password ?
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.

Whats is TWO_TASK in Oracle Database ?
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

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

Where GWYUID defined and what is its used in Oracle Applications ?
GWYUID is defined in dbc i.e. Database Connect Descriptor file . It is used to connect to database by think clients.

If APPS_MRC schema is not used in 11.5.10 and higher then How MRC is working ?
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.

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

How you will avoid your query from using indexes?
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.

What is a OUTER JOIN?
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.

Which is more faster - IN or EXISTS?
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 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.


When do you use WHERE clause and when do you use HAVING clause?
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.

There is a % sign in one field of a column. What will be the query to find it?
SELECT column_name FROM table_name WHERE column_name LIKE ‘%\%%’ ESCAPE ‘\’;

Where will you find forms configuration details apart from xml file ?
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.

What is forms server executable Name ?
f60srvm

What are different modes of forms in which you can start Forms Server and which one is default ?
You can start forms server in SOCKET or SERVLET by defualt Forms are configured to start in socket mode.

How you will start Discoverer in Oracle Apps 11i ?
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)

How many ORACLE HOME are Oracle Apps and whats significance of each ?
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.


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

Where is plssql cache stored in Oracle Apps ?
Usually two type of cache session and plssql stored under $IAS_ORACLE_HOME/Apache/modplsql/cache

What happens if you don't give cache size while defining Concurrent Manager ?
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.

There are lot of DBC file under $FND_SECURE, How its determined that which dbc file to use from $FND_SECURE ?
This value is determined from profile option "Applications Database ID"

What is RRA/FNDFS ?
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 .

What is PCP is Oracle Applications 11i ?
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.

Why I need two Concurrent Processing Nodes or in what scenarios PCP is Used ?
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.


Output and Logfiles for requests executed on source Instance not working on cloned Instance
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.


How to confirm if Report Server is Up and Running ?
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


What is difference between ICM, Standard Managers and CRM in Concurrent Manager ?
# 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.


What is difference between SUBSTR and INSTR?
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.

Which data type is used for storing graphics and images?
Raw, Long Raw, and BLOB.

What is difference between SQL and SQL*PLUS?
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.

What is difference between UNIQUE and PRIMARY KEY constraints?
An UNIQUE key can have NULL whereas PRIMARY key is always not NOT NULL. Both bears unique values.

What is difference between Rename and Alias?
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.


What are various joins used while writing SUBQUERIES?
=, , IN, NOT IN, IN ANY, IN ALL, EXISTS, NOT EXISTS.
What is use of Apps listener ?
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.

How to start Apps listener ?
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)

How to confirm if Apps Listener is Up and Running ?
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)


What is Web Listener ?
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.

How will you find Invalid Objects in database ?
using query SQLPLUS> select count(*) from dba_objects where status like 'INVALID';

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

How to compile JSP in Oracle Apps ?
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


What is difference between ADPATCH and OPATCH ?
# ADPATCH is utility to apply oracle apps Patches whereas
# OPATCH is utility to apply database patches


Can you use both ADPATCH and OPATCH in Apps ?
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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