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INFORMATICA INTERVIEW QUESTIONS - Extracted from GeekInterview.com by Deepak Babuhttp://prdeepakbabu.wordpress.com
1.Informatica - Why we use lookup transformations?
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QUESTION #1 Lookup Transformations can access data from relational tables that are not sources in mapping. With Lookup transformation, we can accomplish the following tasks: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 transformation to determine whether the records already exist in the target or not. Click Here to view complete document No best answer available. Please pick the good answer available or submit your answer. January 19, 2006 01:12:33 sithusithu Member Since: December 2005 Contribution: 161 #1
RE: Why we use lookup transformations?
======================================= Nice Question If we don't have a look our datawarehouse will be have more unwanted duplicates Use a Lookup transformation in your mapping to look up data in a relational table view or synonym. Import a lookup definition from any relational database to which both the Informatica Client and Server can connect. You can use multiple Lookup transformations in a mapping Cheers Sithu
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======================================= Lookup Transformations used to search data from relational tables/FLAT Files that are not used in mapping. Types of Lookup: 1. Connected Lookup 2. UnConnected Lookup ======================================= The main use of lookup is to get a related value either from a relational sources or flat files ======================================= The following reasons for using lookups.....
1)We use Lookup transformations that query the largest amounts of data to improve overall performance. By doing that we can reduce the number of lookups on the same table.
2)If a mapping contains Lookup transformations we will enable lookup caching if this option is not enabled . We will use a persistent cache to improve performance of the lookup whenever possible. We will explore the possibility of using concurrent caches to improve session performance. We will use the Lookup SQL Override option to add a WHERE clause to the default SQL statement if it is not defined We will add ORDER BY clause in lookup SQL statement if there is no order by defined. We will use SQL override to suppress the default ORDER BY statement and enter an override ORDER BY with fewer columns. Indexing the Lookup Table We can improve performance for the following types of lookups: For cached lookups we will index the lookup table using the columns in the lookup ORDER BY statement. For Un-cached lookups we will Index the lookup table using the columns in the lookup where condition.file:///C|/Perl/bin/result.html (2 of 363)4/1/2009 7:50:58 PM
3)In some cases we use lookup instead of Joiner as lookup is faster than joiner in some cases when lookup contains the master data only.
4)This lookup helps in terms of performance tuning of the mappings also.
======================================= Look up Transformation is like a set of Reference for the traget table.For example suppose you are travelling by an auto ricksha..In the morning you notice that the auto driver showing you some card and saying that today onwards there is a hike in petrol.so you have to pay more. So the card which he is showing is a set of reference for there costumer..In the same way the lookup transformation works. These are of 2 types : a) Connected Lookup b) Un-connected lookup Connected lookup is connected in a single pipeline from a source to a target where as Un Connected Lookup is isolated with in the mapping and is called with the help of a Expression Transformation.
======================================= Look up tranformations are used to Get a related value Updating slowly changing dimension Caluculating expressions =======================================
2.Informatica - While importing the relational source definition from database, what are the meta data of source U iQUESTION #2 Source name Database location Column names Datatypes Key constraints
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September 28, 2006 06:30:08 srinvas vadlakonda RE: While importing the relational source defintion fr...
======================================= source name data types key constraints database location ======================================= Relational sources are tables views synonyms. Source name Database location Column name Datatype Key Constraints. For synonyms you will have to manually create the constraints. =======================================
3.Informatica - How many ways you can update a relational source defintion and what r they?QUESTION #3 Two ways 1. Edit the definition 2. Reimport the defintion
Click Here to view complete document No best answer available. Please pick the good answer available or submit your answer. January 30, 2006 04:59:06 gazulas Member Since: January 2006 Contribution: 17 #1
RE: How many ways you can update a relational source d...
======================================= in 2 ways we can do it 1) by reimport the source definition 2) by edit the source definition
4.Informatica - Where should U place the flat file to import thefile:///C|/Perl/bin/result.html (4 of 363)4/1/2009 7:50:58 PM
flat file defintion to the designer?QUESTION #4 Place it in local folderClick Here to view complete document No best answer available. Please pick the good answer available or submit your answer. December 13, 2005 08:42:59 rishi RE: Where should U place the flat file to import the f... #1
======================================= There is no such restrication to place the source file. In performance point of view its better to place the file in server local src folder. if you need path please check the server properties availble at workflow manager. It doesn't mean we should not place in any other folder if we place in server src folder by default src will be selected at time session creation.
======================================= file must be in a directory local to the client machine. ======================================= Basically the flat file should be stored in the src folder in the informatica server folder. Now logically it should pick up the file from any location but it gives an error of invalid identifier or not able to read the first row. So its better to keep the file in the src folder.which is already created when the informatica is installed ======================================= We can place source file any where in network but it will consume more time to fetch data from source file but if the source file is present on server srcfile then it will fetch data from source upto 25 times faster than previous. =======================================
5.Informatica - To provide support for Mainframes source data, which files r used as a source definitions?QUESTION #5 COBOL filesClick Here to view complete document
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No best answer available. Please pick the good answer available or submit your answer. October 07, 2005 11:49:42 Shaks Krishnamurthy RE: To provide support for Mainframes source data,whic... #1
======================================= COBOL Copy-book files ======================================= The mainframe files are Used as VSAM files in Informatica by using the Normaliser transformation =======================================
6.Informatica - Which transformation should u need while using the cobol sources as source defintions?
QUESTION #6 Normalizer transformaiton which is used to normalize the data. Since cobol sources r oftenly consists of Denormailzed data.Click Here to view complete document Submitted by: sithusithu
Normalizer transformaiton Cheers, Sithu
Above answer was rated as good by the following members: ramonasiraj ======================================= Normalizer transformaiton Cheers Sithu
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======================================= Normalizer transformaiton which is used to normalize the data =======================================
7.Informatica - How can U create or import flat file definition in to the warehouse designer?
QUESTION #7 U can not create or import flat file defintion in to warehouse designer directly.Instead U must analyze the file in source analyzer,then drag it into the warehouse designer.When U drag the flat file source defintion into warehouse desginer workspace,the warehouse designer creates a relational target defintion not a file defintion.If u want to load to a file,configure the session to write to a flat file.When the informatica server runs the session,it creates and loads the flatfile.Click Here to view complete document No best answer available. Please pick the good answer available or sub