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Adjust contrib/seg &< and &> operators so that r-tree indexing logic

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works properly for 1-D comparisons.  Fix some other errors such as
bogus commutator specifications.
This commit is contained in:
Tom Lane
2005-06-27 00:48:07 +00:00
parent 06ae88a82e
commit 54c80a3434
5 changed files with 60 additions and 54 deletions
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20
contrib/seg/README.seg
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@ -214,7 +214,7 @@ have just 2 significant digits.
USAGE
=====
The access method for SEG is a GiST (gist_seg_ops), which is a
The access method for SEG is a GiST index (gist_seg_ops), which is a
generalization of R-tree. GiSTs allow the postgres implementation of
R-tree, originally encoded to support 2-D geometric types such as
boxes and polygons, to be used with any data type whose data domain
@ -236,23 +236,27 @@ The operators supported by the GiST access method include:
[a, b] >> [c, d] Is right of
[a, b] is occurs entirely to the right of [c, d].
[a, b] >> [c, d] is true if b > c and false otherwise
[a, b] >> [c, d] is true if a > d and false otherwise
[a, b] &< [c, d] Over left
[a, b] &< [c, d] Overlaps or is left of
The segment [a, b] overlaps the segment [c, d] in such a way
that a <= c <= b and b <= d
This might be better read as "does not extend to right of".
It is true when b <= d.
[a, b] &> [c, d] Over right
[a, b] &> [c, d] Overlaps or is right of
The segment [a, b] overlaps the segment [c, d] in such a way
that a > c and b <= c <= d
This might be better read as "does not extend to left of".
It is true when a >= c.
[a, b] = [c, d] Same as
The segments [a, b] and [c, d] are identical, that is, a == b
and c == d
[a, b] && [c, d] Overlaps
The segments [a, b] and [c, d] overlap.
[a, b] @ [c, d] Contains
The segment [a, b] contains the segment [c, d], that is,