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

On Wed, 18 Sep 2002, Bruce Momjian wrote:

>
> Re-added to open items:
>
> Fix SIMILAR TO to be ANSI compliant or remove it (Peter, Tom)

Tke that @#$(at)$@@$(at)#$ thing out of there until its actually been fully
discussed ... you are starting to remind me of Charlie Brown ... this, I
think, was Thomas' whole point, in that things are added way too faster
and easily without fully understanding all of the ramifications ... let a
discussion cool down *before* you take things off, or add things to, the
list ...

>
> ---------------------------------------------------------------------------
>
> Tom Lane wrote:
> > "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
> >
> > ---------------------------(end of broadcast)---------------------------
> > TIP 4: Don't 'kill -9' the postmaster
> >
>
> --
> Bruce Momjian | http://candle.pha.pa.us
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>