Hello, While reading [1] I notice $subject operators lacks of explanation in documentation.
They where introduced in this commit :
commit 2c0556068fc308ed9cce06c85de7e42305d34b86
Author: Peter Eisentraut <pete...@gmx.net>
Date: Thu May 15 15:50:21 2003 +0000
Indexing support for pattern matching operations via separate operator
class when lc_collate is not C
Comment from this commit :
/*
* The following operators support character-by-character comparison
* of text data types, to allow building indexes suitable for LIKE
* clauses.
*/
So if I understand correctly :
~<~ less than
~>~ greater than
~<=~ less than or equal to
~>=~ greater than or equal to
For all, it is a character-by-character comparison regardless of collation. We
encounter them when we use text_pattern_ops for example :
create index ON users ( location text_pattern_ops);
explain select * from users where location like 'test%';
QUERY PLAN
------------------------------------------------------------------------------------
Index Scan using users_location_idx1 on users (cost=0.43..2.46 rows=54
width=201)
Index Cond: ((location ~>=~ 'test'::text) AND (location ~<~ 'tesu'::text))
Filter: (location ~~ 'test%'::text)
(3 lignes)
Should we add them on this page?
https://www.postgresql.org/docs/devel/static/functions-string.html
Thanks!
1: https://www.postgresql.org/docs/current/static/spgist-builtin-opclasses.html
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Adrien NAYRAT
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