Re: text_pattern_ops index *not* used in field = value condition?

hubert depesz lubaczewski <depesz(at)depesz(dot)com> writes:
> On Sat, Sep 15, 2007 at 11:09:39AM -0400, Tom Lane wrote:
>> = is not one of the members of the text_pattern_ops operator class.

> ok, but is there any reason for this?

Well, at the time those opclasses were invented, the regular = operator
didn't necessarily yield the same result --- in some locales strcoll()
can return "equal" for not-bitwise-equal strings.

As of a couple years ago, the regular text = operator only yields true
for bitwise-equal strings, so we could perhaps drop ~=~ and use = in its
place. But I'd be worried about breaking existing queries that expect
the strangely-named operator to be there.

The operator class structure only permits one equality operator per
opclass, so supporting both is not feasible.

regards, tom lane