Re: Rangejoin rebased - Mailing list pgsql-hackers

From Jeff Davis
Subject Re: Rangejoin rebased
Date
Msg-id CAMp0ubfDLLtnbaHUFEThK5gOx01j4gEAL65UD565oBYx1KszWA@mail.gmail.com
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In response to Re: Rangejoin rebased  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: Rangejoin rebased
List pgsql-hackers
On Fri, Jan 19, 2018 at 2:07 AM, Simon Riggs <simon@2ndquadrant.com> wrote:
> err... that isn't correct. An empty range matches nothing, so can be
> ignored in joins.
>
> So probably best to explain some more, please.

The semantics of R1 @> R2 will return true if R1 is a non-NULL range
and R2 is empty.

It's set semantics, and all sets contain the empty set.

But I understand @> is an important case so I am looking into it.

Regards,
    Jeff Davis


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