Interview Question : How you will find the reason if your Query Execution is very slow.

You will be asked in many interviews

" if user come to you and asked, my query execution is very slow . 

  As a DBA what are the analysis and necessery steps you will take?? "

This is the most blood sucking question in all interviews.  J  

AnyWays, I will tell you the proper Answer here

Possible Answers : 

You Need to check wait event for that session. if query is running & slowness could be due to different reasons...such as -  IO,  Network, High CPU on Other process,. etc.

So, Check initially two points:

blocking sessions and sql elapsed time. Then you can get the direction to follow. With blocking sessions, before do a simple kill, you must identify the reason of the lock, could be a poor tuning sql.

First you have to check is there network traffic or not, second you have to check is the path change check actual path and previous path and also do full table scan, is there any locking on table

Find if there is blocking session. ..second the used tables in query got updated statistics or not....use sql tuning advisor.. implement recomendation after discussion with application team..