NIIT SQL/PLSQL Interview Questions

Explain about Oracle Architecture?
What happens when query is executed?Explain.
What is library cache,Data Dictionary?
What is Result Cache?What is deterministic?
What is collection. Have u declared constructor in collections? Which collection have u used?
What is Multiset operator?
How to find lock on table? 
If application is working slow. what are the issues? (Data volume is not changed,No network issues).
What is explain plan. How do u read explain plan. What informtion does it show?
What is statistics.
If we create a new table say emp, no statistics is generated, no records are inserted than
whether explain plan will be generated?
What are anyalytical function? LAG,LEAD?
What is overloading? Can procedure be overloaded?
What is pragma Autonomous Transaction?
What is Trigger.Can we commit in trigger? Compound Trigger?
Can we commit in compound triggers?
Can function be called from Trigger?
Information about syntax check in library cache is obtained from?
Information about symantic check in library cache is obtained from?
What is Soft parse,Hard parse?
A table has record with value 20. updating the value as 30, what information would be in undo segment and what in redo logs.
What is the minimum no of redo logs required?
Whether Archiver process is necessary?