Informatica interview questions and answers
1.What is difference between Star and Snowflake schema?
2.What is parallel processing or partitioning a session and what is benefit of it?
- Partitioning a session means solo implementation sequences within the session.
- Partitioning option will increase the performance through parallel data processing.
- It will let you split the large data set into smaller subsets which can be processed in parallel to get a better session performance.
3. What are different ways to implement parallel processing in informatica?
- Database partition
- Round Robin partitioning
- Hash auto-keys partitioning
- Hash user-keys partitioning
- Key range partitioning
- Pass through partitioning
4. What is the difference between OLTP and OLAP?
5. What is a surrogate key?
Answer: Surrogate key is a unique identification key, which can be declared as the primary key instead of a “real” or natural key. There can be several natural keys that can be declared as the primary key and these all are called as candidate key. So surrogate key is a candidate key.
Informatica interview questions on Transformation:
6. What is the difference between active and passive transformation?
Active Transformation: They either change the number or rows that pass through the transformation, change the transformation boundary or change the row type.
Passive Transformation: They do not change the number of rows that pass through the transformation, transaction boundary or the row type.
7. What is the difference between ROUTER and FILTER?
8. How do you increase the performance of Joiner Transformation?
Answer: We can increase the performance of Joiner Transformation in following ways:
- Performs Join in database when it is possible.
- For an unsorted transformation, designate the source with fewer rows as the master source.
- For a sorted transformation, designate the source with fewer duplicate key values as the master source.
9. What is an update strategy Transformation in informatica?
Answer: It helps us to tag each record passed through it for insert, update, delete or reject. This information lets the information service know how to treat each record passed to a target. You can set the update strategy at two different levels:
- Session level: Instruct the integration service to either treat all rows in the same way or use instruction coded in the session mappings to flag for different database operations.
- Mapping Level: Use update strategy transformation to flag rows for insert, update, delete or reject.
DD_INSERT(0): Tag the records as an Insert for Target table.
DD_UPDATE(1): Tag the records as an Update for Target table.
DD_DELETE(2): Tag the records as a Delete for Target table.
DD_REJECT(3); Tag the records to be rejected.
10. What are the different types of joins can be performed using Joiner Transformation?
- Normal: It selects only those rows from Master and Detail source which fulfils the conditions.
- Master Outer: It keeps all the rows detail source and matching rows from master.
- Detail Outer: It keeps all rows from master and matching from details.
- Full Outer Join: Keeps all rows from master and detail source.
11. What do you mean by reusable transformation?
Answer: If we have similar mappings to implement across multiple mappings. We can use the reusable transformation, which allows us to reuse the same transformation across mappings. It can be reused only if the metadata requirements are exactly same.
12. What is the difference between mappings and mapplet?
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