Sandeep Joshi <sjoshi(at)Zambeel(dot)com> writes:
> When we specify "primary key" while creating a table, what kind of
> index is created?
btree.
btree is the default index type in all cases in Postgres. It's
considerably better tested than the other types, as well as better-
performing under concurrent access. That's not necessarily an
inherent property of btrees in general, but I think it's a safe
comment about the code that actually exists in Postgres...
regards, tom lane