[ this doesn't seem especially on-topic for pgsql-jdbc, but whatever ... ]
TANWEER ALAM <tanweer76.alam@gmail.com> writes:
> 4. After some more findings. it seems that the parameter
> checkpoint_segments is gone, and has been replaced by min_wal_size
> and max_wal_size.
Indeed, it's gone in 9.5.
> So if the above configuration is deprecated in 9.5 then why this property
> comes as enabled with 9.5 is it a bug?
There is no reference to checkpoint_segments in the postgresql.conf that
9.5 initdb installs. You must have overwritten that with your
configuration file from your older installation, or modified it with some
tuning tool that hasn't been updated for 9.5.
regards, tom lane