Perumal Raj <perucinci(at)gmail(dot)com> writes:
> We have recently upgraded postgres from 9.2 to 11.6 and started seeing
> performance issue immediately and able to fix the performance issue after
> disabling parameter: enable_seqscan.
> Question :
> Should i keep the above parameter always disabled ? If not why the behavior
> changed in Higher version ?
This is unanswerable with the amount of information you've given.
Yes, turning off enable_seqscan is a bad idea in general, but why
you got a worse plan without that requires details.
https://wiki.postgresql.org/wiki/Slow_Query_Questions
regards, tom lane