Re: [PATCH] Support empty ranges with bounds information

[Mark Dilger]

> On Mar 2, 2021, at 11:34 AM, Joel Jacobson <j...@compiler.org> wrote:
> 
> Yes. It's random, since equality isn't changed, the sort operation cannot 
> tell the difference, and nor could a user who isn't aware of upper() / 
> lower() could reveal differences.

This sounds unworkable even just in light of the original motivation for this 
whole thread.  If I use your proposed regexp_positions(string text, pattern 
text, flags text) function to parse a large number of "positions" from a 
document, store all those positions in a table, and do a join of those 
positions against something else, it's not going to work.  Positions will 
randomly vanish from the results of that join, which is going to be really 
surprising.  I'm sure there are other examples of Tom's general point about 
compares-equal-but-not-equal datatypes.

—
Mark Dilger
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