Re: AW: [HACKERS] Re: Subselects open issue Nr. NEW

Thomas Lockhart <lockhart@alumni.caltech.edu>

From: "Thomas G. Lockhart" <lockhart@alumni.caltech.edu>
To: "Vadim B. Mikheev" <vadim@sable.krasnoyarsk.su>
Cc: Zeugswetter Andreas SARZ <Andreas.Zeugswetter@telecom.at>, "'Bruce Momjian'" <maillist@candle.pha.pa.us>, "'pgsql-hackers@hub.org'" <pgsql-hackers@hub.org>
Date: 1998-02-17T16:48:27Z
Lists: pgsql-hackers
> But yes, I agree that the left-right approach would be intuitive (same as
> compound index).
> In mathematics it is called lexical order, I only thought this would be hard
> to implement.
> Also there are a lot of operators (all negated Op's that) will want an _OR_
> e.g. !=~, not only <>

We had started discussing this back when we implemented the general SQL92
syntax for multiple left-hand arguments in expressions.

One possibility was to make the generalization that any operator with "!" or
"<>" (others too?) in the operator string would be handled as a negation, and
all others otherwise. Then, many operators would "magically" work correctly or
intuitively, while a few, perhaps, would not behave correctly. However, imho
this is preferable to not allowing _any_ of these, and perhaps we would learn
over the next few months a way to tighten it up...

                                                       - Tom