Hi all,
This was the question recently I encountered in an interview. I gave the
answers below but that doesn't seem to satisfy the interviewer.

QUESTION:-
SELECT COUNT (*) FROM TABLE_NAME:
The query ran fine and I got the output in less than 25 seconds.
The next day I ran the same query and I got the output after 15 minutes.
What is the reason for this? As a DBA what is that you will check
immediately?

My Answer:-
1. Mass insert or mass delete would have happened in the table,
Statistics were not gathered after that .So the performance has
degraded.
2. Statistics would have been deleted.

Are there any other reasons for the performance degradation?

Thanks in advance

JAIMURUGAN
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