Question { Cap Gemini, 9661 }

what is fact and what types of fact tables is there

Answer

Fact: It is an object that is being analyzed.

Fact table: It consists of a composite key and facts, where ever attribute of the composite key is a foreign key to the dimension table or summarized information.

Two Types Of Fact Tables:
1) Cumulative Fact Table: Describes what was happened over the period of time. They contain addition facts.
2) Snap shot Fact Table: Deals with the particular period time. They contain non-additive and semi-additive facts.

Question { TCS, 10153 }

which is better perfomancewise lookup or joiner and why?can anyone give example?

Answer

R u looking for flat or database file?
Generally sorted joiner more effective on flat files than lookup, because sorted joiner uses merge join and cache less rows. Lookup caches always whole file. If the file is not sorted, it can be comparable. Lookups into DB table can be effective if the DB can return sorted data fast and the amount of data is small, because lookup can create whole cache in memory. If DB responses slowly or big amt of data r processed, lookup cache initialization can be really slow.
Then it can be better use sorted joiner, which throws data to output as reads them on input.

Question { EXL, 18641 }

What is use of batch file in informatica?
How many types of batch file in informatica?

Answer

With the batch file , we can run sessions either in sequential or in concurrently.

Grouping of Sessions is known as Batch.

Two types of batches :
1)Sequential: Runs Sessions one after another.
2)Concurrent: Run the Sessions at the same time.


If u have sessions with source-target dependencies u have to go for sequential batch to start the sessions one after another. If u have several independent sessions u can use concurrent batches Which run all the sessions at the same time.