Informatica Interview Questions – Part – 1

1. Difference between static and dynamic cache and explain with one example?
Answer : Static – once the data is cached , it will not change, example unconnected lookup uses static cache.
Dynamic – the cache is updated as to reflect the update in the table (or source) for which it is reffering to.(ex. Connected lookup).

2. What is update strategy transformation ?
Answer : The model you choose constitutes your update strategy, how to handle changes to existing rows. In powercenter and powermart, you set your update strategy at two different levels:
Within a session : when you configure a session, you can instruct the informatica server to either treat all rows in the same way (for example, treat all rows as inserts), or use instructions coded into the session mapping to flag rows for different database operations.
Within a mapping : within a mapping, you use the update strategy transformation to flag rows for insert, delete, update, or reject. Update strategy is used to update the target.

3. What is the procedure to load the fact table. Give in detail?
Answer : Based on the requirement to your fact table, choose the sources and data and transform it based on 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 with the foreign keys from the source tables.

4. When we create a target as flat file and source as oracle. How can I specify first rows as column names in flat files?
Answer : Use a pre sql statement., but this is a hard coding method. If you change the column names or put in extra columns in the flat file, you will have to change the insert statement.
You can also achieve this by changing the setting in the informatica repository manager to display the columns heading. The only disadvantage of this is that it will be applied on all the files that will be generated by this server.

5. When to use Abort, Decode functions?
Answer : Abort can be used to Abort / stop the session on an error condition. If the primary key column contains NULL, and you need to stop the session from continuing then you may use ABORT function in the default value for the port. It can be used with IIF and DECODE function to Abort the session.