p kirti <kirtip92(at)gmail(dot)com> writes:
> We have recently upgraded our project with a huge DB from Postgres v9.1 to
> v9.4. The whole system performance has degraded alarmingly after the
> upgrade. Simple operations that were taking only a few seconds in Postgres
> 9.1 are now taking minutes of time.
Are you certain nothing else changed? Same hardware, same OS, same
database configuration settings?
Once you've eliminated issues like that, you'd need to drill down deeper.
There's useful advice to help crystallize the situation at
https://wiki.postgresql.org/wiki/Slow_Query_Questions
regards, tom lane