Re: The TODO List (Was: Re: Open 7.3 items)

"Marc G. Fournier" <scrappy(at)hub(dot)org> writes:
> I'm in agreement with Thomas here ... unless a problem has been defined a
> bit more specifically then 'it isn't posix compliant', it shouldn't be
> considered an open item ... please remove?

A quick review of SQL99 says that their notion of SIMILAR TO patterns
is an unholy witches' brew: it does *both* common-or-garden regexp
expressions and LIKE patterns. Specifically, I see these
metacharacters:

| OR (regexp-ish)

* repeat 0 or more times (regexp-ish)

+ repeat 1 or more times (regexp-ish)

% match any character sequence (like LIKE)

_ match any one character (like LIKE)

[...] almost-but-not-quite-regexp-ish character class

(...) grouping (regexp-ish)

plus a just-like-LIKE treatment of a selectable escape character.

But the most important variation from common regex practice is that
(if I'm reading the spec correctly) the pattern must match to the
entire target string --- ie, it's effectively both left- and right-
anchored. This is like LIKE patterns but utterly unlike common regexp
usage.

I could live with the fact that our regexp patterns don't implement all
of the spec-mandated metacharacters. But I do not think we can ignore
the difference in anchoring behavior. This is not a subset of the spec
behavior, it is just plain wrong.

I vote with Peter: we fix this or we disable it before 7.3 release.
It is not anywhere near spec compliant, and we will be doing no one
a favor by releasing it in the current state.

regards, tom lane