LATEST INFORMATICA FAQ”S
Question.1 What will happen if you are using Update Strategy Transformation and your session is configured for “insert”?
Answer: If U 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 update or delete ,, then the info server will not consider UPD for performing any DB operations.ELSE U can use the UDP session level options instead of using a UPD in mapping just select the update inn 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.
Question.2 How to get two targets T1 containing distinct values and T2 containing duplicate values from one source S1.
Answer: Use filter transformation for loading the target with no duplicates and for the other transformation load it directly from source.
Question.3 Where is the cache stored in INFORMATICA?
Answer: INFORMATICA Server.
Question.4 In a Joiner transformation ,you should specify the source with fewer rows as the master source Why?
Answer: Joiner transformation compares each row of the master source against the detail source . The fewer unique rows in the master the fewer iterations of the join comparison occur, which speeds the join process.
Question.5 What are the various test procedures used to check whether the data is loaded in the backend, performance of the mapping ,and quality of the data loaded in INFORMATICA.
Answer: Some of the steps could be:
Check in the workflow monitor status ,whether no of records in source and no. of actual records loaded are equal.
Check for the duration for a workflow to succeed.
Check in the session logs for data loaded.
Question.6 What is polling?
Answer: 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.
Question.7 Partitioning ,Bitmap Indexing (when to use ), how will the bitmap indexing will effect the Performance.
Answer: 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 used bitmap indexers for de—normalized data or low cardinalities. The condition is the amount of DISTINCE rows should be less than 4 % of the total rows. If it satisfies the given condition then bitmap indexers will optimize the performance for this kind of tables.
Question.8 Where do we use MQ series source qualifier, application multi group source qualifier Just give an example for a better understanding.
Answer: We can use a MQ Series SQ when we have a MQ messaging system as source (queue.) system as source (QUEQE) When there is need to extend data from a QUEQUE, which will basically have messages in XML format we will use a JMS or a MQ SQ depending on the messaging system . If you have a TIBCO EMS QUEQE, use a JMS source and JMS SQ and an XML Parser ,or if you have a MQ series QUEQE, then use a MQ SQ which will be associated with a Flat file or a Cobol file.
Question.9 What is meant by junk Attribute in INFORNATICA?
Answer: Junk Dimension a Dimension is called junk dimension if it contains attribute which are rarely changed or modified example In Banking Domain ,we can fetch four attributes accounting to a junk dimensions like from the Overall_ Transaction_ master table t put flag t CMP flag del flag advance flag all these attributes can be a part of a junk dimensions.
Question.10 Explain about incremental aggregation with an example?
Answer: Incremental aggregation is specially used for tune the performance of the aggregator . It captures the change each time (incrementally) you run the transformation and then performs the aggregation function to the changed rows and not to the entire rows. This improves the performance because you are not reading the entire source, each time you run the session.
Question.11 What are the hierarchies in DWH?
Answer: Data sources, Data acquisition, Warehouse Front end tools, Metadata management, Datawarehouseo operation management.
Question.12 Explain real time complain mappings or complex transformations in INFORMATICA
Answer: Most complex logic we use is de—normalization We don’t have any De—NORMALIZER transformation in INFORMATICA So we will have to use an aggregator followed by an expression. Apart from this ,we use most of the COMPLEXICITY in expression transformation involving lot of nested LIF’s and Decode statements another one is the union transformation and joiner.
Question.13 What are the enhancements made to INFORMATICA 7.1.1 version when compared to 6.2.2 version?
Answer: 1. union & custom transformation 2 Lookup on flat file 3 using PMCMD command.
4 Exporting independent and dependent repository objects. 5. Version controlling 6. Data profiting . 7. Supporting of 64 MB Architecture. 8. Authentication
Question.14 What is the logic will you implement to load the data in to one fact from ‘n’ number of dimension tables?
Answer: To load data into one fact table more than one dimension tables firstly U need to create a fact table and dimension tables later load data into individual dimensions by using sources and transformations (aggregator ,sequence generator, lookup) in mapping designer then to the fact table connect the surrogate to the foreign key and the columns from dimensions to the fact.
Question.15 What are mapping parameters and variables in which situation we can use it?
Answer: If we need to change certain attribution of a mapping after every time the session is run, 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 could edit the parameter file to change the attribute values. This makes the process simple.
Question.16 What is meant by complex mapping?
Answer: Complex mapping means having more business rules.
Question.17 Can we run a group of sessions without using workflow manager?
Answer: Using PMCMD command.
Question.18 IF U had to split the source level key going into two separate tables. One as surrogate and other as primary. Since INFORMATICA does not guarantee keys are loaded property (order) into those tables. What are the different ways you could handle this type of situation?
Answer: Foreign keys.
Question.19 How do I import VSAM files from source to target ? Do I need a special plug —in?
Answer: Using power exchange tool convert VSAM file to oracle tables then do mapping as usual
to the target table.