Re: how is text-equality handled in postgresql?

Ivan Voras <ivoras(at)freebsd(dot)org> writes:
> On 15/01/2014 12:36, Amit Langote wrote:
>> Just to add to this, whenever strcoll() (a locale aware comparator)
>> says two strings are equal, postgres re-compares them using strcmp().

> That seems odd and inefficient. Why would it be necessary? I would think
> indexing (and other collation-sensitive operations) don't care what the
> actual collation result is for arbitrary blobs of strings, as long as
> they are stable?

If we didn't do it like this, we could not use hashing techniques for
text --- at least not unless we could find a hash function guaranteed
to yield the same values for any two strings that strcoll() claims are
equal.

regards, tom lane