1. Explain Dynamic lookup and its need? Why we use dynamic lookup when everything can be done by static lookup?
2. Explain Subquery and correlated subquery?
3. What all tasks have you used in workflow manager?
4. Explain the complex mapping that you have done?
5. Tell me about performance tuning in informatica.?
6. Can you use WHERE clause with HAVING clause in SQL?
Deloitte:
1. What is the difference between View and Materialized View? Explain both.
2. What is the diff between star-schema and snow flake schema?
3. How many schemas did you have in your project? Explain
4. Did you use aggregator transformation in your mapping? How does it work?
Mindtree:
1. In expression transf if you have an input port,variable port1,output port1,variable port2,output port 2 then what is the order of execution?
2. What is aggregator cache size?
3. Explain the need for dynamic lookup?
4. Explin SCD type 2 mapping?
5. Performance tuning?
6. What is the use of sorted input in aggregator transf?How does it work?
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7 comments:
Mindtree Answers:
1)Order of execution is first to last.
2) Default cache size is 2,000,000(around 2MB).
Thanks a lot Balaji
SCD TYPE 2 TABLE MAINTAINS CURRENT DATA+COMPLETE HISTORY.
IT CAN BE IMPLEMENT IN 3 TYPES
1.FLAG CURRENT DATA
2.VERSIONING
3.TIME STAMPING
DIFFERENCE BETWEEN STAR FLAKE STAR SCHEMA AND SNOW FLAKE STAR SCHEMA IS
...IN STAR FLAKE STAR SCHEMA DIMENSION TABLES ARE DENORMALISED AND FACT TABLES ARE NORMALIZED...
///IN SNOW FLAKE STAR SCHEMA BOTH THE DIMENSION AND FACT TABLES ARE NORMALISED///
THE GOAL OF PERFORMANCE TUNING IS TO OPTIMISE SESSION PERFORMANCE BY ELIMINATING PERFORMANCE BOTTLENECKS.TO TUNE THE PERFORMANCE OF A SESSION,FIRST U IDENTIFY APERFORMANCE BOTTLENECK ,ELIMINATE IT,AND THEN IDENTIFY THE NEXT PERFORMANCE BOTTLENECK UNTIL U ARE SATISFIED WITH THE SESSION PERFORMANCE .U CAN USE THE TEST LOAD OPTION TO RUN SESSIONS WHEN U TUNE SESSION PERFORMANCE.
STEPS FOR PERFORMANCE TUNING
1.RUNNING TEST SESSIONS
2.STUDYING PERFORMANCE DETAILS
3.MONITORING SYSTEM PERFORMANCE
4.ELIMINATE SOURCE AND TARGET DATABASE BOTTLENECKS
5.ELIMINATE MAPPING BOTTLENECKS
6.ELIMINATE SESSION BOTTLENECKS
7.ELIMINATE SYSTEM BOTTLENECKS
Mindtree answer
6)Sorted input is used in Aggregator transformation to improve session performance.
Inorder to use sorted input the data must be passed to the Aggr transf sorted by group by port in ascending or descending order.
How sorted input improves session performance?
Sorted input is used to decrease the use of aggregate caches.
It reduces the amount of data cached during the session.
The sorted data must be passed to aggregator transformation by using sorter transformation when we use Sorted Input.
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