Re: Question about rtrees (overleft replacing left in nodes)

From: William White <bwhite(at)frognet(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re: Question about rtrees (overleft replacing left in nodes)
Date: 2004-03-31 21:21:19
Message-ID: 406B364F.2040000@frognet.net
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Tom Lane wrote:

> Right, but what about the existing operators --- what is a more correct
> way to document them?

Ouch.

Appealing to J.F. Allen's terminology ("An Interval-Based Representation
of Temporal Knowledge", Comm ACM 26(11) 832-43), overleft could be
called "left or finishes" (implying all other related conditions, of
which there are a bunch) but this relies too heavily on time notation I
think. "right boundary left of right boundary" is accurate but rather
verbose, "rightoverleft" too confusing. Of course, I suspect most
people will see the operator, not the C function name; if they see the
latter they can read the code anyway.

Perhaps document as S &< T iff S "does not extend to the right
of/beyond" (the right boundary of) T? And either leave the C functions
as-is or give them reasonable names; in either case, "a.high.x <=
b.high.x" is just as clear as any comment.

-- Bill

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