On Mon, Oct 28, 2019 at 11:20 AM Tom Lane <t...@sss.pgh.pa.us> wrote: > > I mean, do we have to break the extensions? If we just added == > > operators that behaved like IS NOT DISTINCT FROM to each datatype, why > > would anything get broken? > > Is that the proposal? I certainly assumed that Eugen had in mind a > parser-level hack, because adding dozens of new operators and their > underlying functions would be a Lot Of Tedious Work. But I agree > that if we did it like that, it (probably) wouldn't break anything.
I'm not sure we've yet converged on a single proposal yet. This seems to be at the spitballing stage. > I'd be somewhat inclined to adopt "===" and "!===" as the standard > names, trading off one more keystroke to get to a point where we > almost certainly aren't conflicting with anybody's existing usage. Maybe. It's an open question in my mind which of those is more likely to be taken already. Javascript uses === and !== for a certain kind of equality comparison, so I'd guess that the chance of someone having used === is better-than-average for that reason. Also, if we decide that the opposite of === is !=== rather than !==, someone may hate us. > One objection to proceeding like that is that there'd be no > visible connection between a datatype's "=" and "===" operators, > removing any hope of someday optimizing, for example, "x IS NOT > DISTINCT FROM 42" into an indexscan on x. We're certainly not > very bright about these constructs today, but at least there > exists the possibility of doing better in future. I suppose > we could think about extending btree opclasses to allow for > an === entry, but that'd be another pile of work ... Yeah. If we went this route, I think we'd probably have to do that extension of the btree operator class machinery first. Virtually nobody is gonna want a new spelling of IS NOT DISTINCT FROM that is shorter but performs terribly. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
