47703453 FAQs on Informatica Final

7/27/2019 47703453 FAQs on Informatica Final

1/55

2011

Pavan

1/5/2011

Informatica


2/5535

Informatica Questions & Answers

1) How can you recognise whether or not the newly added rows in the source are

gets insert in the target?

Ans) 1.checking target success rows in the workflow monitor

2.through scd type2 flag version

2) What is the difference between Informatica 7.0 and 8.0 ?

Ans)Informatica 7.0 Informatica 8.1.1

Architectur

e

Informatica 7.0 is a client

server architecture where

8.0 is service oriented

architecture

PC8 is service-oriented for modularity, scalability

and flexibility.

Service The Repository Service and Integration Service (as

replacement for Rep Server and Informatica

Server) can be run on different

computers in a network (so called nodes), even

redundantly.

Manageme

nt

Management is centralized, that means services

can be started and stopped on nodes via a central

web interface.

Tools Client Tools access the repository via that

centralized machine, resources are distributed

dynamically.

Portability Running all services on one machine is still

possible, of course.

Supports . It has a support for unstructured data which

includes spreadsheets, email, Microsoft Word files,

presentations and .PDF documents. It provideshigh availability, seamless fail over, eliminating

single points of failure.

Performanc

e

grid and pushdown

optimization is not there in

7.0 but in 8.0 these are

available

It has added performance improvements (To bump

up systems performance, Informatica has added

"push down optimization" which moves data

transformation processing to the native relational

database I/O engine whenever its is most

appropriate.)

Capabilities Through 7.0 migration is

critical where as with 8.0

migration is possible and

easy

Informatica has now added more tightly

integrated data profiling, cleansing, and matching

capabilities.

web Informatica has added a new web based

administrative console.

Additional

Transforma

tions

Ability to write a Custom Transformation in C++ or

Java. Midstream SQL transformation has been

added in 8.1.1, not in 8.1.

encryption and description User defined functions


3/5535


is not in 7.0 possible with

8.0

7.0 we cant change the

lookup cache size but with

8.0 we can change the

lookup cache size

.Dynamic configuration of caches and partitioning

Power Center 8 release has "Append to Target file"feature.

3) Performance tuning in Informatica?Ans)

Network connections: The performance of the Informatica Server is related to networkconnections. Data generally moves across a network at less than 1 MB per second, whereas

a local disk moves data five to twenty times faster. Thus network connections often affecton session performance. So avoid network connections.

Flat files: If your flat files stored on a machine other than the informatica server, movethose files to the machine that consists of informatica server.

Relational data sources: Minimize the connections to sources, targets and informatica serverto improve session performance. Moving target database into server system may improve

session performance.Staging areas: If u uses staging areas u force informatica server to perform multiple data

passes. Removing of staging areas may improve session performance.Distributing load: Distributing the session load to multiple informatica servers may improve

session performance.Data Movement: Run the informatica server in ASCII data movement mode improves the

session performance .Because ASCII data movement mode stores a character value in onebyte .Unicode mode takes 2 bytes to store a character.

If a session joins multiple source tables in one Source Qualifier, optimizing the query may

improve performance. Also, single table select statements with an ORDER BY or

GROUP BY clause may benefit from optimization such as adding indexes.We can improve the session performance by configuring the network packet size ,which

allows data to cross the network at one time .To do this go to server manger ,choose serverconfigure database connections.

If u are target consists key constraints and indexes u slow the loading of data .To improvethe session performance in this case drop constraints and indexes before u run the

session and rebuild them after completion of session.Running parallel sessions by using concurrent batches will also reduce the time of loading

the data. So concurrent batches may also increase the session performance .Partitioning the session improves the session performance by creating multiple connections

to sources and targets and loads data in parallel pipe lines.In some cases if a session contains a aggregator transformation, You can use incremental

aggregation to improve session performance.

Avoid transformation errors to improve the session performance.If the session contains lookup transformation You can improve the session performance byenabling the look up cache.

If Ur session contains filter transformation, create that filter transformation nearer to thesources or you can use filter condition in source qualifier.

Aggreagator, Rank and joiner transformation may often decrease the sessionperformance .Because they must group data before processing it. To improve session

performance in this case use sorted ports option.


4/5535


4) Differences between Normalizer and Normalizer transformation.

Ans)

Normalizer Normalization

It is a transformation mainly using for cobol

sources,

To remove the redundancy and

inconsistency

it's change the rows into columns and columns

into rows

Normalizer Transformation can be used to obtain

multiple columns from a single row.

5) How do we do unit testing in Informatica?How do we load data in informatica?Ans) Unit testing are of two types

1. Quantitaive testing2.Qualitative testing

Steps.1. First validate the mapping

2.Create session on the mapping and then run workflow.

Once the session is succeeded the right-click on session and go for statistics tab.There you can see how many number of source rows is applied and how many number ofrows loaded in to targets and how many number of rows rejected. This is called Quantitative

testing.If once rows are successfully loaded then we will go for qualitative testing.Steps

1.Take the DATM(DATM means where all business rules are mentioned to the correspondingsource columns) and check whether the data is loaded according to the DATM in to target

table. If any data is not loaded according to the DATM then go and check in the code andrectify it.This is called Qualitative testing.This is what a developer will do in Unit Testing.

6) How do you handle decimal places while importing a flatfile into informatica?

Ans) While importing flat file definition just specify the scale for a numeric data type. In themapping, the flat file source supports only number data type (no decimal and integer). In

the SQ associated with that source will have a data type as decimal for that number port of

the source .source ->number data type port ->SQ -> decimal data type .Integer is not supported.

Hence decimal is taken care. Import the field as string and then use expression to convert

it, so that we can avoid truncation if decimal places in source itself.

7) Diff between static and dynamic cache? and please explain with one example?Ans) Difference between static and dynamic cache-

Static cache Dynamic cache1) Once the data is cached , it will not

change. example unconnected lookup

uses static cache.

2) The cache is updated as to reflect

the update in the table( or source)

for which it is reffering to.(ex.

connected lookup).

3) while using a static cache in lookup we

can use all operators like =,... while

giving condition in condition tab

4) but in using dynamic cache we

only can use = operator

5) It is read-only cache 6) Dynamic Cache: It is Read and

Write


5/5535


7) Informatica returns value when condition

is true and if it is false it will return

default value in connected look up and

Null value in unconnected look up

8) It will return only if condition is

false

9) We can configure any static or read only

cache for any lookup source.By DefaultIntegration service creates a static

cache.In ths it caches the lookup table,

and when lookup condition is true it

returns a value.

10)To cache a target table/FF src and1)insert rows

or 2)update existing rows in thecache

8) What is power center repository?

Ans) Standalone repository. A repository that functions individually, unrelated and

unconnected to other repositories.Global repository. (PowerCenter only.) The centralized repository in a domain, a group of

connected repositories. Each domain can contain one global repository. The global

repository can contain common objects to be shared throughout the domain through global

shortcuts.Local repository. (PowerCenter only.) A repository within a domain that is not the globalrepository. Each local repository in the domain can connect to the global repository and use

objects in its shared folders.

Power Center repository is used to store informatica's meta data .

Information such as mapping name,location,target definitions,sourcedefinitions,transformation and flow is stored as meta data in the repository.

9) How the informatica server sorts the string values in Ranktransformation?Ans) We can run informatica server either in UNICODE data moment mode or ASCII datamoment mode.Unicode mode: in this mode informatica server sorts the data as per the

sorted order in session. It uses the sort order configured in session properties.

ASCII Mode:in this mode informatica server sorts the data as per the binary order

10) Is sorter an active or passive transformation?What happens if we uncheck the

distinct option in sorter.Will it be under active or passive transformation?Ans) Sorter is an active transformation. if you don't check the distinct option it is

considered as a passive transformation. because this distinct option eliminates the duplicate

records from the table.

11) What is the difference between stop and abort

Ans) stop: In the session if u want to stop a part of batch you must stop the batch,

if the batch is part of nested batch, Stop the outer most batch

Abort:You can issue the abort command , it is similar to stop command except it has 60 second

time out .

If the server cannot finish processing and committing data within 60 sec

12) Explain about Informatica server Architecture?


6/5535


Ans) Informatica Server Architecture is as above.1. Node

2. Integration Server3. Repository Server

13) How can you improve session performance in aggregator transformation?

Ans) There are 3 ways to improve session performance for an aggregator transformation :-

A)1)Size of data cache = Bytes required for variable columns + bytes required for outputcolumns.

2) Size of index cache = size of ports used in group by clause.

B) If you provide sorted data for group by ports aggregation will be faster, so for portswhich are used in group by of an aggregator sort those ports in a sorter.

C) We can use incremental aggregation if we think that there will be no change in data

which is already aggregated.

14) How can we use pmcmd command in a workflow or to run a session

Ans) pmcmd>startworkflow -f foldername workflowname

15) In update strategy target table or flat file which gives more performance ?

why?Ans) Pros: Loading, Sorting, Merging operations will be faster as there is no index concept

and Data will be in ASCII mode.Cons: There is no concept of updating existing records in flat file.

As there is no indexes, while lookups speed will be lesser.

16) What is the difference between filter and lookup transformation?Ans) 1) Filter transformation is an Active transformation and Lookup is a Passive

transformation

2) Filter transformation is used to Filter rows based on condition and Lookup is used to tolook up data in a flat file or a relational table, view, or synonym

17) What are the out put files that the informatica server creates during the

session running?Ans) Informatica server log: Informatica server(on unix) creates a log for all status anderror messages(default name: pm.server.log). It also creates an error log for error

messages.These files will be created in informatica home directory:-

Session log file: Informatica server creates session log file for each session.It writes

information about session into log files such as initialization process,creation of sql

commands for reader and writer threads,errors encountered and load summary.The amount

of detail in session log file depends on the tracing level that you set.

Session detail file: This file contains load statistics for each targets in mapping.Sessiondetail include information such as table name,number of rows written or rejected.U

can view this file by double clicking on the session in monitor window

Performance detail file: This file contains information known as session performance detailswhich helps you where performance can be improved.To genarate this file select

the performance detail option in the session property sheet.


7/5535


Reject file: This file contains the rows of data that the writer does notwrite to targets.

Control file: Informatica server creates control file and a target file when you run a session

that uses the external loader.The control file contains the information about thetarget flat file such as data format and loading instructios for the external loader.

Post session email: Post session email allows you to automatically communicate informationabout a session run to designated recipents.You can create two different

messages.One if the session completed sucessfully the other if the session fails.

Indicator file: If you use the flat file as a target,You can configure the informatica server tocreate indicator file.For each target row,the indicator file contains a number to indicate

whether the row was marked for insert,update,delete or reject.output file: If session writes to a target file,the informatica server creates the target file

based on file prpoerties entered in the session property sheet.

Cache files: When the informatica server creates memory cache it also creates cache files.

For the following circumstances informatica server creates index and datacache files:-Aggreagtor transformation

Joiner transformationRank transformationLookup transformation

18) How many types of dimensions are available in Informatica?

Ans) The types of dimensions available are:1. Junk dimension

2. Degenerative Dimension3. Conformed Dimension

19) Define informatica repository?

Ans) Infromatica Repository:The informatica repository is at the center of the informatica

suite. You create a set of metadata tables within the repository database that theinformatica application and tools access. The informatica client and server access therepository to save and retrieve metadata.

20) How do you configure mapping in informaticaAns) You should configure the mapping with the least number of transformations andexpressions to do the most amount of work possible. You should minimize the amount of

data moved by deleting unnecessary links between transformations.For transformations that use data cache (such as Aggregator, Joiner, Rank, and Lookup

transformations), limit connected input/output or output ports. Limiting the number ofconnected input/output or output ports reduces the amount of data the transformations

store in the data cache.

You can also perform the following tasks to optimize the mapping:

Configure single-pass reading.Optimize datatype conversions.

Eliminate transformation errors.Optimize transformations.

Optimize expressions.

21) How can you create or import flat file definition in to the warehouse designer?

Ans) You can not create or import flat file defintion in to warehouse designerdirectly.Instead you must analyze the file in source analyzer,then drag it into the warehouse


8/5535


designer.When you drag the flat file source defintion into warehouse desginer workspace,the

warehouse designer creates a relational target defintion not a file defintion.If you want toload to a file,configure the session to write to a flat file.When the informatica server runs

the session,it creates and loads the flat file.

22) When we create a target as flat file and source as oracle.. how can i specifyfirst rows as column names in flat files...Ans) use a pre sql statement....but this is a hardcoding method...if you change the columnnames or put in extra columns in the flat file, you will have to change the insert statement.

You can also achive this by changing the setting in the Informatica Repository manager todisplay the columns heading. The only disadvantage of this is that it will be applied on all

the files that will be generated by This serverWhen importing a flat file into target designer a flat file import wizard appears. In this there

is an option as 'import field names from first line'. Just check this option so integrationserver treats first row values as column names.

23) Discuss the advantages & Disadvantages of star & snowflake schema?

Ans) In a STAR schema there is no relation between any two dimension tables, whereas in

a SNOWFLAKE schema there is a possible relation between the dimension tables.In starschema there is no relationship between two relational tables. All dimensions are de-normalized and query performence is degrades. In this snow flake schema dimensions are

normalized. In this SF schema table space is increased.Maintenence cost is high.Queryperformence is increaced.

24) Difference between Rank and Dense Rank?

Ans) Rank:1

2


9/5535


There is one file called the bad file which generally has the format as *.bad and it containsthe records rejected by informatica server. There are two parameters one fort the types of

row and other for the types of columns. The row indicators signifies what operation is goingto take place ( i.e. insertion, deletion, updation etc.). The column indicators contain

information regarding why the column has been rejected.( such as violation of not nullconstraint, value error, overflow etc.) If one rectifies the error in the data preesent in the

bad file and then reloads the data in the target,then the table will contain only valid data.

26) What is the difference between connected and unconnected stored

procedures.

Ans) Unconnected:

The unconnected Stored Procedure transformation is not connected directly to the flow ofthe mapping. It either runs before or after the session, or is called by an expression in

another transformation in the mapping.

connected:

The flow of data through a mapping in connected mode also passes through the StoredProcedure transformation. All data entering the transformation through the input ports

affects the stored procedure. You should use a connected Stored Procedure transformationwhen you need data from an input port sent as an input parameter to the stored procedure,

or the results of a stored procedure sent as an output parameter to another transformation.

by using unconnected stored procedure

reusability is possiblein connected only one time is possible

27) Which tasks can be performed on port level(using one specific port)?Ans) I think unconnected Lookup or expression transformation can be used for single portfor a row.

28) What are main advantages and purpose of using Normalizer Transformation inInformatica?Ans) Narmalizer Transformation is used mainly with COBOL sources where most of the time

data is stored in de-normalized format. Also, Normalizer transformation can be used tocreate multiple rows from a single row of data

29) What is the difference between constraind base load ordering and target load

plan

Ans) Constraint based load ordering

example:Table 1---Master

Table 2---Detail

If the data in table1 is dependent on the data in table2 then table2 should be loaded first.Insuch cases to control the load order of the tables we need some conditional loading which is

nothing but constraint based load

In Informatica this feature is implemented by just one check box at the session level.


10/5535


A CBl specifies the order in which data loads into the targets based on key constraintsA target load plan defines the order in which data being extracted from the source qualifier

30) What is difference between IIF and DECODE function

Ans) You can use nested IIF statements to test multiple conditions. The following example

tests for various conditions and returns 0 if sales is zero or negative:

IIF( SALES > 0, IIF( SALES < 50, SALARY1, IIF( SALES < 100, SALARY2, IIF( SALES < 200,

SALARY3, BONUS))), 0 )

You can use DECODE instead of IIF in many cases. DECODE may improve readability. The

following shows how you can use DECODE instead of IIF :

SALES > 0 and SALES < 50, SALARY1,

SALES > 49 AND SALES < 100, SALARY2,

SALES > 99 AND SALES < 200, SALARY3,

SALES > 199, BONUS)

Decode function can used in sql statement. where as if statment cant use with SQLstatement.

31) How can u work with remote database in informatica?did u work directly by

using remote connections?

Ans) To work with remote datasource u need to connect it with remote connections.But it is

not preferable to work with that remote source directly by using remote connections.Instead u bring that source into U r local machine where informatica server resides.If u

work directly with remote source the session performance will decreases by passing lessamount of data across the network in a particular time.

32) How to import oracle sequence into Informatica.

Ans) CREATE ONE PROCEDURE AND DECLARE THE SEQUENCE INSIDE THE

PROCEDURE,FINALLY CALL THE PROCEDURE IN INFORMATICA WITH THE HELP OF STORED

PROCEDURE TRANSFORMATION.

33) Identifying bottlenecks in various components of Informatica and resolvingthem.

Ans) The best way to find out bottlenecks is writing to flat file and see where the bottleneck is .

34) What is parameter file?

Ans) For UNIX shell users, enclose the parameter file name in single quotes:-paramfile '$PMRootDir/myfile.txt'

For Windows command prompt users, the parameter file name cannot have beginning ortrailing spaces. If the name includes spaces, enclose the file name in double quotes:

-paramfile ?$PMRootDirmy file.txt?Note: When you write a pmcmd command that includes a parameter file located on another

machine, use the backslash () with the dollar sign ($). This ensures that the machine where


11/5535


the variable is defined expands the server variable.pmcmd startworkflow -uv USERNAME -pv PASSWORD -s SALES:6258 -f east -w wSalesAvg

-paramfile '$PMRootDir/myfile.txt'

35)What is the difference between summary filter and detail filterAns) Summary filter can be applied on a group of rows that contain a common value.

whereas detail filters can be applied on each and every rec of the data base.

36) What is the difference between Narmal load and Bulk load?

Ans) Normal Load: Normal load will write information to the database log file so that if any

recorvery is needed it is will be helpful. when the source file is a text file and loading data toa table,in such cases we should you normal load only, else the session will be failed.

Bulk Mode: Bulk load will not write information to the database log file so that if any

recorvery is needed we can't do any thing in such cases.

compartivly Bulk load is pretty faster than normal load.

37) How u will create header and footer in target using informatica?

Ans) If you are focus is about the flat files then one can set it in file properties whilecreating a mapping or at the session level in session properties

38) What are two types of processes that informatica runs the session?Ans) Load manager Process: Starts the session, creates the DTM process, and sends post-

session email when the session completes.The DTM process. Creates threads to initialize the session, read, write, and transform data,

and handle pre- and post-session operations.

39) What r the types of groups in Router transformation?Ans) A Router transformation has the following types of groups:

InputOutputInput Group

The Designer copies property information from the input ports of the input group to create aset of output ports for each output group.

Output Groups

There are two types of output groups:

User-defined groupsDefault group

You cannot modify or delete output ports or their properties.

40) What are the real time problems generally come up while doing/runningmapping/any transformation?can any body explain with example.

Ans) Here are few real time examples of problems while running informatica mappings:

1) Informatica uses OBDC connections to connect to the databases.The database passwords (production ) is changed in a periodic

manner and the same is not updated at the Informatica side.Your mappings will fail in this case and you will get database connectivity error.

2) If you are using Update strategy transformation in the mapping, in the session properties


12/5535


you have to select Treat Source Rows : Data Driven. If we do not select this Informaticaserver will ignore updates and it only Inserts rows.

3) If we have mappings loading multiple target tables we have to provide the Target LoadPlan

in the sequence we want them to get loaded.4) Error:Snapshot too old is a very common error when using Oracle tables. We get this

errorwhile using too large tables. Idealy we should schelude these loads when server is not very

busy (meaning when no other loads are running).5) We might get some poor performance issues while reading from large tables. All the

source tablesshould be indexed and updated regularly.

41) What is difference between maplet and reusable transformation?

Ans) mapplet:---contains input and output transformations.

--designed in mapplet designer.

--reusable.--contains multiple transformations.

--we use it to reuse multiple tr for a task to be done.

Reusable transformation:-

--no input and output transformation is needed.--designed in mapping designer.

--reusable.--It is a singl transformation

--we create it to reuse a single transformation in future

42) How many types of facts and what are they?Ans) There are

Factless Facts:Facts without any measures.

Additive Facts:Fact data that can be additive/aggregative.Non-Additive facts: Facts that are result of non-additonSemi-Additive Facts: Only few colums data can be added.

Periodic Facts: That stores only one row per transaction that happend over a period of time.Accumulating Fact: stores row for entire lifetime of event.

43) what are load types in informatica and what is delta load

Ans) There are two types of load i) Normal Load ii) Bulk LoadNormal Load-

The integration service writes to the database log then it enters into target.a)performance of loading to target decreases but session recovery occurs.

b)Rollback and commit possible

Bulk Load:

The integration service bypasses the database log without writing into it and directly loadedinto target.

a)Performance increases but session recovery doesnot occur.b) Rollback and commit also not possible.

In bulk loading we need to consider the following:1)Without creating any primary and foreign key at database level but however in target

definition.2)drop index before loading into target and create index after loading.

3)disable enable parallel mode option


13/5535


44) What are the session parameters?

Ans) Session parameters are like maping parameters,represent values you might want tochange between sessions such as database connections or source files.

Server manager also allows you to create userdefined session parameters.Following areuser defined session parameters:-

Database connectionsSource file names: use this parameter when you want to change the name or location of

session source file between session runs.Target file name : Use this parameter when you want to change the name or location of

session target file between session runs.Reject file name : Use this parameter when you want to change the name or location of

session reject files between session runs.By using Session parameters we can reuse thesession how many times you want. The main purpose of session parameter it represents

connection path to a database system. we can reuse the different types of databases.If you want to use session parameter we have to follow the following procedure

1. Double click the session and select mapping tab in the mapping tab select target

connection, in the target connection select writer property click on Radio Button USEConnection Variable and write the connection variable $$.

After that create a parameter file with .txt or .prm using the following syntax[folder.session]$$


14/5535


47) Where to store informatica rejected data? How to extract the informaticarejected data ?

Ans) The reject rows say for example due to unique key constrain is all pushed by sessioninto the $PMBadFileDir (default relative path is


15/5535


Ans) We can use the following Mapping for slowly Changing dimension table.

? Expression? Lookup

? Filter? Sequence Generator

? Update Strategy

54) How do I import VSAM files from source to target. Do I need a special plugin

Ans) As far my knowledge by using power exchange tool convert vsam file to oracle tables

then do mapping as usual to the target table.

55) What is meant by aggregate fact table and where is it used?Ans) Basically fact tables are two kinds 1. Aggregated factable and Factless fact table.

Agregated factable has aggregarted columns. for eg. Total-Sal, Dep-Sal. where as infactless factable will not have aggregated colums and it only has FK to the Dimension

tables.

56) What are Target Types on the Server?

Ans) Target Types are File, Relational and ERP.

57) What are mapping parameters and varibles in which situation we can use it

Ans) If we need to change certain attributes of a mapping after every time the session isrun, it will be very difficult to edit the mapping and then change the attribute. So we use

mapping parameters and variables and define the values in a parameter file. Then we couldedit the parameter file to change the attribute values. This makes the process simple.

Mapping parameter values remain constant. If we need to change the parameter value thenwe need to edit the parameter file .

But value of mapping variables can be changed by using variable function. If we need toincrement the attribute value by 1 after every session run then we can usemapping

variables .

In a mapping parameter we need to manually edit the attribute value in the parameter fileafter every session run.

58) How do you create single lookup transformation using multiple tables?

Ans) Write a override sql query. Adjust the ports as per the sql query.

59) Why is meant by direct and indirect loading options in sessions?

Ans) when we use multiple source files, we create a file containing the names anddirectories of each source file we want the PowerCenter Server to use. This file is referred to

as a file list.

when configuring the session properties,choose Indirect in the Source Filetype field,enter

the file name of the file list in the Source Filename field and enter the location of the file list

in the Source File Directory field. When the session starts, thePowerCenter Server reads thefile list, then locates and reads the first file source in the list. After the PowerCenter Server

reads the first file, it locates and reads the next file in the list.

60) What are Target Options on the Servers?Ans) Target Options for File Target type are FTP File, Loader and MQ.

There are no target options for ERP target type.Target Options for Relational are Insert, Update (as Update), Update (as Insert), Update

(else Insert), Delete, and Truncate Table.


16/5535


61) what are the difference between view and materialized view?

Ans) Materialized views are schema objects that can be used to summarize, precompute,replicate, and distribute data. E.g. to construct a data warehouse.

A materialized view provides indirect access to table data by storing the results of a query in

a separate schema object. Unlike an ordinary view, which does not take up any storagespace or contain any data

62) To achieve the session partition what are the necessary tasks you have to do?

Ans) Configure the session to partition source data.Install the informatica server on a machine with multiple CPU?s.

63) On a day, I load 10 rows in my target and on next day if I get 10 more rows to

be added to my target out of which 5 are updated rows how can I send them totarget? How can I insert and update the record?

Ans) We can achieve this task by SCD(slowly changing dimensions) type 1.

1. have a lookup on target and check for the primary key values, if the record is new, insert

the record and if the record has changed, then update the record.2. for this u have to create a update strategy transformation inside the mapping.

64) Can you generate reports in Informatcia?

Ans) Yes. By using Metadata reporter we can generate reports in informatica.Informatica istool to support data extracting ,transforming and loading.i am not sure informatica support

for reporting.my experience is concern informatica doesn't support reporting.

65) Explain use of update strategy transformationAns) This is the important transformation,is used to maintain the history data or just most

recent changes into the target table.

We can set or flag the records by using these two levels.1) Within a session:When you configure the session,you can instruct the informatica server to either treat all

the records in the same way.2) Within a mapping:

within a mapping we use update strategy transformation to flag the records likeinsert,update,delete or reject.

66) The designer includes a "Find" search tool as part of the standard tool bar.

What can it be used to find?Ans) Search for two things:

1. Transformations

2. Ports in the Transformation

67) If you have four lookup tables in the workflow. How do you troubleshoot toimprove performance?

Ans) There r many ways to improve the mapping which has multiple lookups.1) we can create an index for the lookup table if we have permissions(staging area).

2) divide the lookup mapping into two (a) dedicate one for insert means: source - target,,these r new rows . only the new rows will come to mapping and the process will be fast . (b)


17/5535


dedicate the second one to update : source=target,, these r existing rows. only the rowswhich exists allready will come into the mapping.

3)we can increase the chache size of the lookup.

68) How to recover sessions in concurrent batches?Ans) If multiple sessions in a concurrent batch fail, you might want to truncate all targets

and run the batch again. However, if a session in a concurrent batch fails and the rest ofthe sessions complete successfully, you can recover the session as a standalone session.

To recover a session in a concurrent batch:1.Copy the failed session using Operations-Copy Session.

2.Drag the copied session outside the batch to be a standalone session.3.Follow the steps to recover a standalone session.

4.Delete the standalone copy.

69) Briefly explian the Versioning Concept in Power Center 7.1.Ans) When you create a version of a folder referenced by shortcuts, all shortcuts continue

to reference their original object in the original version. They do not automatically update to

the current folder version.

For example, if you have a shortcut to a source definition in the Marketing folder, version1.0.0, then you create a new folder version, 1.5.0, the shortcut continues to point to thesource definition in version 1.0.0.

Maintaining versions of shared folders can result in shortcuts pointing to different versions

of the folder. Though shortcuts to different versions do not affect the server, they mightprove more difficult to maintain. To avoid this, you can recreate shortcuts pointing to earlier

versions, but this solution is not practical for much-used objects. Therefore, when possible,do not version folders referenced by shortcuts.

70) Why we use lookup transformations?

Ans) Get a related value-Get the Employee Name from Employee table based on the

Employee IDPerform Calculation.Update slowly changing dimension tables - We can use unconnected lookup transformationto determine whether the records already exist in the target or not.

71) What is Datadriven?Ans) The informatica server follows instructions coded into update strategy transformationswith in the session maping determine how to flag records for insert, update, delete or

reject. If you do not choose data driven option setting,the informatica server ignores allupdate strategy transformations in the mapping.If the data driven option is selected in the

session properties,it follows the instructions in the update strategytransformation in the mapping o.w it follows instuctions specified in the session.

72) What is batch and describe about types of batches?

Ans) Batch--- is a group of any thing

Different batches ----Different groups of different things.There are two types of batches

1. Concurrent2. Sequential

73) Can Informatica be used as a Cleansing Tool? If Yes, give example of

transformations that can implement a data cleansing routine.


18/5535


Ans) Yes, we can use Informatica for cleansing data. some time we use stages to cleansingthe data. It depends upon performance again else we can use expression to cleasing data.

For example an feild X have some values and other with Null values and assigned to target

feild where target feild is notnull column, inside an expression we can assign space or someconstant value to avoid session failure.

The input data is in one format and target is in another format, we can change the format in

expression.

we can assign some default values to the target to represent complete set of data in thetarget.

74) Differences between connected and unconnected lookup?

Ans) Connected lookup:-1> Receives input values diectly from the pipe line.

2> You can use a dynamic or static cache.

3> Cache includes all lookup columns used in the maping.4> Support user defined default values.

Unconnected lookup:-1> Receives input values from the result of a lkp expression in a another transformation.

2> You can use a static cache.3> Cache includes all lookup out put ports in the lookup condition and the lookup/return

port.4> Does not support user defiend default values.

75) How to read rejected data or bad data from bad file and reload it to target?

Ans) Correction the rejected data and send to target relational tables using loadorderutility. Find out the rejected data by using column indicatior and row indicator.

76) What are the various test procedures used to check whether the data is loadedin the backend, performance of the mapping, and quality of the data loaded in

INFORMATICA. 2) What are the common problems developers face while ETLdevelopment

Ans) If you want to know the performance of a mapping at transformation level, then select

the option in the session properties-> collect performance data. At the run time in themonitor you can see it in the?performance tab or you can get it from a file.

The PowerCenter Server names the file session_name.perf, and stores it in the same

directory as the session log. If there is no session-specific directory for the session log,thePowerCenter Server saves the file in the default log files directory.

Quality of the data loaded depends on the quality of data in the source. If cleansing is

required then have to perform some data cleansing operations in informatica. Final data willalways be clean if followed.

77) What are the types of data that passes between informatica server and stored

procedure?

Ans) Three types of data:-

Input/Out put parameters


19/5535


Return ValuesStatus code.

78) What are the types of metadata that stores in repository?

Ans) Following are the types of metadata that stores in the repository:-Database connections

Global objectsMappings

MappletsMultidimensional metadata

Reusable transformationsSessions and batches

Short cutsSource definitions

Target defintionsTransformations.

79) How to move the mapping from one database to another?

Ans) 1.? Open the mapping you want to migrate.? Go to File Menu - Select 'Export Objects'

and give a name - an XML file will be generated.? Connect to the repository where you wantto migrate and then select File Menu - 'Import Objects' and select theXML file name.

2.? Connect to both the repositories.??Go to the source folder and select mapping namefrom the?object navigator and select?'copy' from 'Edit' menu.? Now, go to the target folder

and select 'Paste' from 'Edit' menu.? Be sure you open the target folder.

80) What is the target load order?Ans) The Integration Service reads sources in a target load order group concurrently, and it

processes target load order groups sequentially.To specify the order in which the Integration Service sends data to targets, create one

source qualifier for each target within a mapping. To set the target load order, you then

determine in which order the Integration Service reads each source in the mapping.

To set the target load order:

1.Create a mapping that contains multiple target load order groups.2.Click Mappings > Target Load Plan.

The Target Load Plan dialog box lists all Source Qualifier transformations in the mappingand the targets that receive data from each source qualifier.

3.Select a source qualifier from the list.4.Click the Up and Down buttons to move the source qualifier within the load order.

5.Repeat steps 3 to 4 for other source qualifiers you want to reorder.6.Click OK.

81) Can we eliminate duplicate rows by using filter and router transformation ?if

so explain me in detail .

Ans) U can use SQL query for uniqness if the source is Relational

But if the source is Flat file then u should use Shorter or Aggregatot transformation

82) What is parameter file?Ans) Parameter file is to define the values for parameters and variables used in a session.A

parameter


20/5535


file is a file created by text editor such as word pad or notepad.You can define the following values in parameter file:-

Maping parametersMaping variables

session parameters.

83) Can you use the maping parameters or variables created in one maping intoanother maping?Ans) No

84) How do u check the source for the latest records that are to be loaded into thetarget. i.e i have loaded some records yesterday, today again the file has been

populated with some more records today, so how do i find the records populatedtoday.

Ans) a) Create a lookup to target table from Source Qualifier based on primary Key.b) Use and expression to evaluate primary key from target look-up. ( If a new source record

look-up primary key port for target table should return null). Trap this with decode and

proceed.

85) What is the default join that source qualifier provides?Ans) Inner equi join. cross join

86) Why did you use stored procedure in your ETL Application?Ans) usage of stored procedure has the following advantages

1) checks the status of the target database2) drops and recreates indexes

3) determines if enough space exists in the database4) performs aspecilized calculation

87) What is the diff b/w Stored Proc (DB level) & Stored proc trans

(INFORMATICA level) ? again why should we use SP trans ?

Ans) Stored Procedure tr:-===========In database :-

we execute it using "EXECUTE ST_PRO_NAME" commandIn Informatica:-

when we create stored procedure tr it contains a return port by default.this port is already assigned to the st pro which we selected while creating this tr.

just we need to connect it to output port in target and connect input ports to it.

Uses:-1)used to populate and maintain database.

2)allow user defined variables, conditional statements and other powerful programmimg

features.

3)very useful as they are flexible than SQL statements.4)provide error handling and logging necessary for critical tasks.

5)used for many other tasks.

88) What is difference between stored procedure transformation and externalprocedure transformation?

Ans) In case of storedprocedure transformation procedure will be compiled and executed ina relational data source.U need data base connection to import the stored procedure


21/5535


in to u?r maping.Where as in external procedure transformation procedure or function willbe executed out side of data source.Ie u need to make it as a DLL to access in u r

maping.No need to have data base connection in case of external procedure transformation.

89) What is the procedure to load the fact table.Give in detail?Ans) your business needs. For the fact table, you need a primary key so use a sequence

generator transformation to generate a unique key and pipe it to the target (fact) table withthe foreign keys from the source tables.

90) What is the status code?

Ans) Status code provides error handling for the informatica server during the session.Thestored procedure issues a status code that notifies whether or not stored procedure

completed sucessfully.This value can not seen by the user.It only used by the informaticaserver to determine whether to continue running the session or stop.

91) What are variable ports and list two situations when they can be used?

Ans) We have mainly tree ports Inport, Outport, Variable port. Inport represents data is

flowing into transformation. Outport is used when data is mapped to next transformation.Variable port is used when we mathematical calculations are required. If any addition i will

be more than happy if you can share.We can use variable ports to store values of previousrecords which is not otherwise possible in Informatica.

92) While importing the relational source defintion from database, what are themeta data of source you import?

Ans) Source nameDatabase location

Column namesDatatypes

Key constraints.

93) What is Transaction?

Ans) A transaction can be define as DML operation.

means it can be insertion,modification or deletion of data performed by users/

analysts/applicatorsTransaction is a logical unit of work that comprises one or more sql statements executed by

a single user

94) How can you access the remote source into your session?Ans) Relational source: To acess relational source which is situated in a remote place ,u

need to configure database connection to the datasource.FileSource : To access the remote source file you must configure the FTP connection to the

host machine before you create the session.

Hetrogenous : When U?r maping contains more than one source type,the server manager

creates a hetrogenous session that displays source options for all types.

95) What are the basic needs to join two sources in a source qualifier?Ans) Basic need to join two sources using source qualifier:

1) Both sources should be in same database2) The should have at least one column in common with same data types

96) What are the diffrence between joiner transformation and source qualifier

transformation?


22/5535


Ans) Joiner Transformation can be used to join tables from hetrogenious (differentsources), but we still need a common key from both tables. If we join two tables without a

common key we will end up in a Cartesian Join. Joiner can be used to join tables fromdifference source systems where as Source qualifier can be used to join tables in the same

database.We definitely need a common key to join two tables no mater they are in same database or

difference databases.

97) With out using Updatestretagy and sessons options, how we can do the

update our target table?

Ans) n the target definition there is an option to write the update override query, here wecan specify the update query and this will update the rows.

98) What are the types of maping in Getting Started Wizard?

Ans) Simple Pass through maping :Loads a static fact or dimension table by inserting all rows. Use this mapping when you

want to drop all existing data from your table before loading new data.

Slowly Growing target :Loads a slowly growing fact or dimension table by inserting new rows. Use this mapping to

load new data when existing data does not require updates.

99) in the concept of mapping parameters and variables, the variable value will be

saved to the repository after the completion of the session and the next time whenu run the session, the server takes the saved variable value in the repository and

starts assigning the next value of the saved value. for example i ran a session andin the end it stored a value of 50 to the repository.next time when i run the

session, it should start with the value of 70. not with the value of 51. how to dothis.

Ans) u can do one thing after running the mapping,, in workflow manager

start-------->session.

right clickon the session u will get a menu, in that go for persistant values, there u will findthe last value stored in the repository regarding to mapping variable. then remove it and

put ur desired one, run the session... i hope ur task will be done

100) What are the joiner caches?

Ans)master rows.After building the caches, the Joiner transformation reads records from the detail source

and perform joins.

101) What transformation you can use inplace of lookup?Ans) Look-up transformation can serve in so many situations.

So, if you can a bit particular about the scenarioo that you are talking about, it will be easyto interpret.

102) How to define Informatica server?

Ans) Informatica server is the main server component in informatica product family..Whichis resonsible for reads the data from various source system and tranforms the data

according to business rule and loads the data into the target table

103) How can u complete unrcoverable sessions?


23/5535


Ans) Under certain circumstances, when a session does not complete, you need to truncatethe target tables and run the session from the beginning. Run the session from the

beginning when the Informatica Server cannot run recovery or when running recoverymight result in inconsistent data.

104) How to lookup the data on multiple tabels.

Ans) if the two tables are relational, then u can use the SQL lookup over ride option to jointhe two tables in the lookup properties.u cannot join a flat file and a relatioanl table.

eg: lookup default query will be select lookup table column_names from lookup_table. u can

now continue this query. add column_names of the 2nd table with the qualifier, and a whereclause. if u want to use a order by then use -- at the end of the order by.

105) What is the default source option for update stratgey transformation?

Ans) default option for update stratgey t/r is dd_insert or we can put '0'.in session level data driven

106)What is pushdown optimizations in pc 8.x with example?

Ans) Use pushdown optimization to push transformation logic to the source or target

database. The Integration Service analyzes the transformation logic, mapping, and sessionconfiguration to determine the transformation logic it can push to the database. At run time,the IntegrationService executes any SQL statement generated against the source or target

tables, and it processes any transformation logic that it cannot push to the database.Select one of the following values:

- None. The Integration Service does not push any transformation logic to the database.

- To Source. The Integration Service pushes as much transformation logic as possible to thesource database.

- To Target. The Integration Service pushes as much transformation logic as possible to the

target database.

- Full. The Integration Service pushes as much transformation logic as possible to both thesource database and target database.

- $$PushdownConfig. The $$PushdownConfig mapping parameter allows you to run the

same session with different pushdown optimization configurations at different times. Formore information about configuring the $$PushdownConfig mapping parameter and

parameter file, see Using the $$PushdownConfig Mapping Parameter.

107) In a scenario I have col1, col2, col3, under that 1,x,y, and 2,a,b and I want inthis form col1, col2 and 1,x and 1,y and 2,a and 2,b, what is the procedure?

Ans) Use Normalizer :

create two ports -

first port occurs = 1second make occurs = 2

two output ports are created andconnect to target

108) If u had to split the source level key going into two seperate tables. One as

surrogate and other as primary. Since informatica does not gurantee keys areloaded properly(order!) into those tables. What are the different ways you could

handle this type of situation?


24/5535


Ans) foreign key

109) What are the transformations that restricts the partitioning of sessions? Ans)Advanced External procedure tranformation and External procedure transformation: This

transformation contains a check box on the properties tab to allow partitioning.Aggregator Transformation: If u use sorted ports You can not parttion the assosiated source

Joiner Transformation : You can not partition the master source for a joiner transformationNormalizer Transformation

XML targets.

POWER EXCHANGE SOURCE and TARGETS

Advanced External procedure tranformation and External procedure transformation: This

transformation contains a check box on the properties tab to allow partitioning.Aggregator Transformation: If u use sorted ports You can not parttion the assosiated source

Joiner Transformation : You can not partition the master source for a joiner transformationNormalizer Transformation

XML targets.

110) Can u explain one critical mapping? 2.performance issue which one is better?

whether connected lookup tranformation or unconnected one?

Ans) it depends on your data and the type of operation u r doing.

If u need to calculate a value for all the rows or for the maximum rows coming out of the

source then go for a connected lookup.

Or,if it is not so then go for unconnectd lookup.

Specially in conditional case like,

we have to get value for a field 'customer' from order tabel or from customer_data table,onthe basis of following rule:

If customer_name is null then ,customer=customer_data.ustomer_Id

otherwise

customer=order.customer_name.

so in this case we will go for unconnected lookup

Dimesions are

1.SCD2.Rapidly changing Dimensions3.junk Dimensions

4.Large Dimensions5.Degenerated Dimensions

6.Conformed Dimensions.

111) What is hash table informatica?


25/5535


Ans) In hash partitioning, the Informatica Server uses a hash function to group rows ofdata among partitions. The Informatica Server groups the data based on a partition key.Use

hash partitioning when you want the Informatica Server to distribute rows to the partitionsby group. For example, you need to sort items by item ID, but you do not know how many

items have a particular ID number.

112) In a joiner transformation, you should specify the source with fewer rows asthe master source. Why?Ans) Joiner transformation compares each row of the master source against the detailsource. The fewer unique rows in the master, the fewer iterations of the join comparison

occur, which speeds the join process.Joiner Transformation will cache Master table's datahence it is advised to define table with less #of rows as master.

113) what is difference between lookup cashe and unchashed lookup? Can i run

the mapping with out starting the informatica server?Ans) The difference between cache and uncacheed lookup iswhen you configure the lookup

transformation cache lookup it stores all the lookup table data in the cache when the first

input record enter into the lookup transformation, in cache lookup the select statementexecutes only once and compares the values of the input record with the values in the

cachebut in uncache lookup the the select statement executes for each input recordentering into the lookup transformation and it has to connect to database each timeentering the new record

114) What are the tasks that Loadmanger process will do?

Ans) Manages the session and batch scheduling: Whe you start the informatica server theload maneger launches and queries the repository for a list of sessions configured to run

on the informatica server.When you configure the session the loadmanager maintains list oflist of sessions and session start times.When you sart a session loadmanger fetches the

session information from the repository to perform the validations and verifications prior tostarting DTM process.

Locking and reading the session: When the informatica server starts a session lodamaagerlocks the session from the repository.Locking prevents you starting the session again andagain.

Reading the parameter file: If the session uses a parameter files,loadmanager reads the

parameter file and verifies that the session level parematers are declared in the fileVerifies permission and privelleges: When the sesson starts load manger checks whether or

not the user have privelleges to run the session.

Creating log files: Loadmanger creates logfile contains the status of session.

115) How can we join the tables if the tables have no primary and forien keyrelation and no matchig port to join?

Ans) without common column or common data type we can join two sources using dummyports.

1.Add one dummy port in two sources.

2.In the expression trans assing '1' to each port.2.Use Joiner transformation to join the sources using dummy port(use join conditions).

116) In a sequential Batch how can we stop single session?
http://www.coolinterview.com/interview/7946/http://www.coolinterview.com/interview/7946/http://www.coolinterview.com/interview/7946/http://www.coolinterview.com/interview/7946/


26/5535


Ans) We can stop it using PMCMD command or in the monitor right click on that perticularsession and select stop.this will stop the current session and the sessions next to it.

117) How to create the staging area in your database

Ans) A Staging area in a DW is used as a temporary space to hold all the records from thesource system. So more or less it should be exact replica of the source systems except for

the laod startegy where we use truncate and reload options.

So create using the same layout as in your source tables or using the Generate SQL optionin the Warehouse Designer tab.

118) What is the logic will you implement to laod the data in to one factv from 'n'

number of dimension tables.Ans) Noramally evey one use

!)slowly changing diemnsions

2)slowly growing dimensions

119) What r the basic needs to join two sources in a source qualifier?Ans) The both the table should have a common field with same data type.Its not necessary both should follow primary and foreign relationship. If any relation ship

exists that will help u in performance point of view.The two sources should be a relationaland homogeneous

120) What are various types of Aggregation?

Ans) Various types of aggregation are SUM, AVG, COUNT, MAX, MIN, FIRST, LAST,MEDIAN, PERCENTILE, STDDEV, and VARIANCE.

121) If you want to create indexes after the load process which transformation

you choose?

Ans) Its usually not done in the mapping(transformation) level. Its done in session level.Create a command task which will execute a shell script (if Unix) or any other scripts whichcontains the create index command. Use this command task in the workflow after the

session or else, You can create it with a post session command.

122) How the informatica server increases the session performance through

partitioning the source?

Ans) For a relational sources informatica server creates multiple connections for eachparttion of a single source and extracts seperate range of data for each connection.

Informatica server reads multiple partitions of a single source concurently.Similarly forloading also informatica server creates multiple connections to the target and loads

partitions of data concurently.

For XML and file sources,informatica server reads multiple files concurently.For loading the

data informatica server creates a seperate file for each partition(of a source file). You canchoose to merge the targets.

123) How can you improve the performance of Aggregate transformation?

Ans) we can improve the agrregator performence in the following ways

1.send sorted input.2.increase aggregator cache size.i.e Index cache and data cache.


27/5535


3.Give input/output what you need in the transformation.i.e reduce number of input andoutput ports.

Use Sorter Transformation to sort input in aggregrator propertiesfilter the records before

124) What r the unsupported repository objects for a mapplet?Ans) Source definitions. Definitions of database objects (tables, views, synonyms) or filesthat provide source data.

Target definitions. Definitions of database objects or files that contain the target data.Multi-dimensional metadata. Target definitions that are configured as cubes and

dimensions.

Mappings. A set of source and target definitions along with transformations containingbusiness logic that you build into the transformation. These are the instructions that the

Informatica Server uses to transform and move data.Reusable transformations. Transformations that you can use in multiple mappings.

Mapplets. A set of transformations that you can use in multiple mappings.

Sessions and workflows. Sessions and workflows store information about how and when theInformatica Server moves data. A workflow is a set of instructions that describes how and

when to run tasks related to extracting, transforming, and loading data. A session is a typeof task that you can put in a workflow. Each session corresponds to a single mapping.

125) What r the types of lookup caches?

Ans) 1)Static Cache2)Dynamic Cache

3)Persistent Cache4)Reusable Cache

5)Shared Cache

126) What r the tasks that source qualifier performs?

Ans) Join data originating from the same source database. You can join two or more tables

with primary-foreign key relationships by linking the sources to one Source Qualifier.Filter records when the Informatica Server reads source data. If you include a filter

condition, the Informatica Server adds a WHERE clause to the default query.Specify an outer join rather than the default inner join. If you include a user-defined join,

the Informatica Server replaces the join information specified by the metadata in the SQLquery.

Specify sorted ports. If you specify a number for sorted ports, the Informatica Server addsan ORDER BY clause to the default SQL query.

Select only distinct values from the source. If you choose Select Distinct, the Informatica

Server adds a SELECT DISTINCT statement to the default SQL query.Create a custom query to issue a special SELECT statement for the Informatica Server to

read source data. For example, you might use a custom query to perform aggregate

calculations or execute a stored procedure.

127) If a session fails after loading of 10,000 records in to the target.How can uload the records from 10001 th record when u run the session next time in

informatica 6.1?Ans) Running the session in recovery mode will work, but the target load type should be

normal. If its bulk then recovery wont work as expected

128) Why dimenstion tables are denormalized in nature ?


28/5535


Ans) Because in Data warehousing historical data should be maintained, to maintainhistorical data means suppose one employee details like where previously he worked, and

now where he is working, all details should be maintain in one table, if u maintain primarykey it won't allow the duplicate records with same employee id. so to maintain historical

data we are all going for concept data warehousing by using surrogate keys we can achievethe historical data(using oracle sequence for critical column).

so all the dimensions are marinating historical data, they are de normalized, because ofduplicate entry means not exactly duplicate record with same employee number another

record is maintaining in the table.

129) What is polling?Ans) It displays the updated information about the session in the monitor window. The

monitor window displays the status of each session when you poll the informatica server.

130) In which condtions we can not use joiner transformation(Limitaions of joinertransformation)?

Ans) Both pipelines begin with the same original data source.Both input pipelines originate from the same Source Qualifier transformation.

Both input pipelines originate from the same Normalizer transformation.Both input pipelines originate from the same Joiner transformation.

Either input pipelines contains an Update Strategy transformation.Either input pipelines contains a connected or unconnected Sequence Generator

transformation.

131) What r the active and passive transforamtions?

Ans) Transformations can be active or passive. An active transformation can change the

number of rows that pass through it, such as a Filter transformation that removes rows thatdo not meet the filter condition.

A passive transformation does not change the number of rows that pass through it, such asan Expression transformation that performs a calculation on data and passes all rowsthrough the transformation.

132) What is the maplet?

Ans) Maplet is a set of transformations that you build in the maplet designer and You canuse in multiple mapings.

A Mapplet is a reusable object defined with business logic using set of transformations. It iscreated using Mapplet designer tool.

133) What is surrogatekey ? In ur project in which situation u has used ? explainwith example ?

Ans) A surrogate key is system genrated/artificial key /sequence number or A surrogate key is a

substitution for the natural primary key.It is just a unique identifier or number for each row that

can be used for the primary key to the table. The only requirement for a surrogate primary key isthat it is unique for each row in the tableI it is useful because the natural primary key (i.e.

Customer Number in Customer table) can change and this makes updates more difficult.but In


29/5535


my project, I felt that the primary reason for the surrogate keys was to record the changing

context of the dimension attributes.(particulaly for scd )The reason for them being integer and

integer joins are faster. Unlike other

134) Partitioning, Bitmap Indexing (when to use), how will the bitmap indexingwill effect the performance

Ans) Bitmap indexing a indexing technique to tune the performance of SQL queries.The default type is B-Tree indexers which is of high cardinality (normalized data).You can use bitmap indexers for de-normalized data or low cardinalities. Thecondition is the amount of DISTINCT rows should be less than 4% of the total rows.If it satisfies the given condition then bitmap indexers will optimize the performancefor this kind of tables.

135) What is difference between dimention table and fact table and what are

different dimention tables and fact tables

Ans) In the fact table contain measurable data and less columns and meny rows,

It's contain primarykey

Diffrent types of fact tables:

additive,non additive, semi additive

In the dimensions table contain textual descrption of data and also contain meny columns,less

rows

Its contain primary key

Both contains primary keys

Fact tables are which are measurable and have less columns and more rowsBut in dimension which are not measurable

136) What are cost based and rule based approaches and the difference

Ans) Cost based and rule based approaches are the optimization techniques whichare used in related to databases, where we need to optimize a sql query.Basically Oracle provides Two types of Optimizers (indeed 3 but we use only thesetwo techniques., bcz the third has some disadvantages.)

When ever you process any sql query in Oracle, what oracle engine internally doesis, it reads the query and decides which will the best possible way for executing thequery. So in this process, Oracle follows these optimization techniques.1. cost based Optimizer(CBO): If a sql query can be executed in 2 different ways( like may have path 1 and path2 for same query),then What CBO does is, itbasically calculates the cost of each path and the analyses for which path the costof execution is less and then executes that path so that it can optimize the queyexecution.


30/5535


2. Rule base optimizer(RBO): this basically follows the rules which are needed forexecuting a query. So depending on the number of rules which are to be applied,the optimzer runs the query.

Use:If the table you are trying to query is already analysed, then oracle will go with CBO.

If the table is not analysed , the Oracle follows RBO.For the first time, if table is not analysed, Oracle will go with full table scan.

137) What will happen if you are using Update Strategy Transformation and your

session is configured for "insert"? What are the types of External Loader availablewith Informatica? If you have rank index for top 10. However if you pass only 5

records, what will be the output of such a Rank Transformation?

Ans) if u r using a update strategy in any of ur mapping, then in session properties u have to set

treat source rows as Data Driven. if u select insert or udate or delete, then the info server will not

consider UPD for performing any DB operations.ELSE

u can use the UPD session level options. instead of using a UPD in mapping just select the

update in treat source rows and update else insert option. this will do the same job as UPD. but

be sure to have a PK in the target table.2) for oracle : SQL loader

for teradata:tpump,mload.

3) if u pass only 5 rows to rank, it will rank only the 5 records based on the rank port.

138) What is aggregate cache in aggregator transforamtion?

Ans) When you run a workflow that uses an Aggregator transformation, theInformatica Server creates index and data caches in memory to process the

transformation. If the Informatica Server requires more space, it stores overflowvalues in cache files.

139) Which transformation should we use to normalize the COBOL and relationalsources?

Ans)The Normalizer transformation normalizes records from COBOL and relationalsources, allowing you to organize the data according to your own needs. ANormalizer transformation can appear anywhere in a data flow when you normalizea relational source. Use a Normalizer transformation instead of the Source Qualifiertransformation when you normalize a COBOL source. When you drag a COBOLsource into the Mapping Designer workspace, the Normalizer transformationautomatically appears, creating input and output ports for every column in the

source

140) What are the measure objects

Ans) Aggregate calculation like sum,avg,max,min these are the measure objetcs.

141) What is DTM process?

Ans) After the loadmanger performs validations for session,it creates the DTMprocess.DTM is to create and manage the threads that carry out the session tasks.Icreates the


31/5535


master thread.Master thread creates and manges all the other threads.DTM meansdata transformation manager.in informatica this is main back ground process.it runafter complition of load manager.in this process informatica server search sourceand tgt connection in repository if it correct then informatica server fetch the datafrom source and load it to target.

142)What are the options in the target session of update strategy transformation?Ans) InsertDeleteUpdateUpdate as updateUpdate as insertUpdate esle insert

Truncate table

143) What are the designer tools for creating tranformations?

Ans) Mapping designerTansformation developer

Mapplet designer.

144) What is Code Page used for?

Ans) Code Page is used to identify characters that might be in different languages.If you are importing Japanese data into mapping, you must select the Japanese codepage of source data.

145) Can i start and stop single session in concurent bstch?

Ans) Just right click on the particular session and going to recovery option or byusing event wait and event rise

146) What are the rank caches?Ans) During the session ,the informatica server compares an inout row with rows inthe datacache.If the input row out-ranks a stored row,the informatica serverreplaces thestored row with the input row.The informatica server stores group information in anindex cache and row data in a data cache.

147) Why and where we are using factless fact table?

Ans) Factless Fact Tables are the fact tables with no facts or measures(numericaldata). It contains only the foriegn keys of corresponding Dimensions. Factless fact isused to track the events by using the key values

148) How can you delete duplicate rows with out using Dynamic Lookup? Tell meany other ways using lookup delete the duplicate rows?

Ans) For example u have a table Emp_Name and it has two columns Fname, Lnamein the source table which has douplicate rows. In the mapping Create Aggregatortransformation. Edit the aggregator transformation select Ports tab select Fnamethen click the check box on GroupBy and uncheck the (O) out port. select Lnamethen uncheck the (O) out port and click the check box on GroupBy. Then create 2new ports Uncheck the (I) import then click Expression on each port. In the first new


32/5535


port Expression type Fname. Then second Newport type Lname. Then close theaggregator transformation link to the target table.

149) What are the different options used to configure the sequential batches?

Ans)Two optionsRun the session only if previous session completes sucessfully. Always runs the

session.

150) How to Generate the Metadata Reports in Informatica?

Ans)You can generate PowerCenter Metadata Reporter from a browser on anyworkstation, even a workstation that does not have PowerCenter tools installed.

151) How do we estimate the number of partitons that a mapping really requires?

Is it dependent on the machine configuration?

Ans) It depends upon the informatica version we r using. suppose if we r usinginformatica 6 it supports only 32 partitions where as informatica 7 supports 64partitions.

152) How the informatica server sorts the string values in Ranktransformation?Ans) When the informatica server runs in the ASCII data movement mode it sortssession data using Binary sortorder.If you configure the seeion to use a binary sortorder,theinformatica server caluculates the binary value of each string and returns thespecified number of rows with the higest binary values for the string.

153) How can U create or import flat file definition in to the warehouse designer?

Ans) U can create flat file definition in warehouse designer.in the warehousedesigner,u can create new target: select the type as flat file. save it and u can entervarious columns for that created target by editing its properties.Once the target iscreated, save it. u can import it from the mapping designer.

154) To provide support for Mainframes source data,which files r used as a sourcedefinitions?

Ans) COBOL Copy-book files

155) Can u copy the session to a different folder or repository?

Ans) In addition, you can copy the workflow from the Repository manager. This willautomatically copy the mapping, associated source,targets and session to thetarget folder.Yes it is possible. For copying a session to a folder in the samerepository or to another in a different repository, we can use the repositorymanager ( which is client sid etool).Simply by just dragging the session to the targetdestination, the session will be copied.

156) How to get two targets T1 containing distinct values and T2 containing

duplicate values from one source S1.

Ans) Use filter transformation for loading the target with no duplicates. and for theother transformation load it directly from source.The above requirement can be achivedusing Lookup transformation in Dynamic mode

157) What is worklet and what use of worklet and in which situation we can use it


33/5535


Ans) A set of worlflow tasks is called worklet,Workflow tasks means1)timer2)decesion3)command4)eventwait5)eventrise6)mail etc......

158) We are using Update Strategy Transformation in mapping how can we know

whether insert or update or reject or delete option has been selected during

running of sessions in Informatica.Ans) In Designer while creating Update Strategy Transformation uncheck "forwardto next transformation". If any rejected rows are there automatically it will beupdated to the session log file.Update or insert files are known by checking the target file or table only.

159) What are the different types of Type2 dimension maping?

Ans)Type2 Dimension/Version Data Maping: In this maping the updated dimensionin the source will gets inserted in target along with a new version number. Newlyaddeddimension in source will inserted into target with a primary key.

Type2 Dimension/Flag current Maping: This maping is also used for slowly changingdimensions.In addition it creates a flag value for changed or new dimension.

Flag indiactes the dimension is new or newlyupdated.Recent dimensions will getssaved with cuurent flag value 1. And updated dimensions are saved with the value0.

Type2 Dimension/Effective Date Range Maping: This is also one flavour of Type2maping used for slowly changing dimensions.This maping also inserts both new andchanged dimensions in to the target. And changes are tracked by the effective daterange for each version of each dimension.

160) Can you use the maping parameters or variables created in one maping intoany other reusable transformation?

Ans)Yes.Because reusable tranformation is not contained with any maplet ormaping.

161) What is tracing level?

Ans)Ya its the level of information storage in session log.The option comes in the properties tab of transformations. By default it remains"Normal". Can beVerbose InitialisationVerbose DataNormal

or Terse.

162) What is meant by EDW?

Ans) EDW is Enterprise Datawarehouse which means that its a centralised DW forthe whole organization.

this apporach is the apporach on Imon which relies on the point of having a singlewarehouse/centralised where the kimball apporach says to have seperate datamarts for each vertical/department.


34/5535


Advantages of having a EDW:

1. Golbal view of the Data

2. Same point of source of data for all the users acroos the organization.

3. able to perform consistent analysis on a single Data Warehouse.

to over come is the time it takes to develop and also the management that isrequired to build a centralised database.

163) There are 1000 source tables containing the same data with different file

formats,now i want to load into a single target table ..how to achieve ?

Ans) first u should convert diff. file format to one format then create 1 to 1mapping,run it and see the o/p in unix whether file is posted or not.

164) Where is the cache stored in informatica?

Ans) Cache is stored in the Informatica server memory and over flowed data isstored on the disk in file format which will be automatically deleted after thesuccessful completion of the session run. If you want to store that data you have touse a persistant cache.

165) Can you start a batches with in a batch?

Ans)You can not. If you want to start batch that resides in a batch,create a newindependent batch and copy the necessary sessions into the new batch.

166) What is a command that used to run a batch?

Ans) pmcmd is used to start a batch.

167) What are the unsupported repository objects for a mapplet?Ans) COBOL source definition

Joiner transformationsNormalizer transformationsNon reusable sequence generator transformations.Pre or post session stored procedures

Target defintionsPower mart 3.5 style Look Up functionsXML source definitionsIBM MQ source defintions.

168) What r the types of metadata that stores in repository?

Ans) Source definitions. Definitions of database objects (tables, views, synonyms) orfiles that provide source data.

Target definitions. Definitions of database objects or files that contain the targetdata.Multi-dimensional metadata. Target definitions that are configured as cubes anddimensions.Mappings. A set of source and target definitions along with transformationscontaining business logic that you build into the transformation. These are theinstructions that the Informatica Server uses to transform and move data.


35/5535


Reusable transformations. Transformations that you can use in multiple mappings.Mapplets. A set of transformations that you can use in multiple mappings.Sessions and workflows. Sessions and workflows store information about how andwhen the Informatica Server moves data. A workflow is a set of instructions thatdescribes how and when to run tasks related to extracting, transforming, andloading data. A session is a type of task that you can put in a workflow. Each

session corresponds to a single mapping.

169) How do we analyse the data at database level?

Ans) Data can be viewed using Informatica's designer tool.If you want to view the data on source/target we can preview the data but withsome limitations.We can use data profiling too.

170) In my source table 1000 rec's r there.I want to load 501 rec to 1000 rec intomy Target table ? how can u do this ?

Ans) You can overide the sql Query in Wofkflow Manager. LIke

select * from tab_name where rownum


36/5535


mappingsessionsystem

174) Identifying bottlenecks in various components of Informatica and resolving

them.

Ans)The best way to find out bottlenecks is writing to flat file and see where thebottle neck is .

175) Can we lookup a table from a source qualifer transformation-unconnectedlookup

Ans) No. we can't do.

I will

47703453 FAQs on Informatica Final

Documents

Transcript of 47703453 FAQs on Informatica Final