Op 16-08-2022 om 13:46 schreef Daniel Gustafsson:
On 16 Aug 2022, at 12:54, Erik Rijkers <e...@xs4all.nl> wrote:
Op 16-08-2022 om 12:36 schreef Daniel Gustafsson:
On 16 Aug 2022, at 12:17, PG Doc comments form <nore...@postgresql.org> wrote:
I have a question regarding the trigram algorithm and I can not find any
information about it in your documentation:
Maybe we should add something about this?
Yeah, it's a bit strange that none of the following strings yield any info on
that page: 'case', 'sensitiv', 'upper', 'lower', and that there is no mention
of the ~ versus ~* difference.
Maybe worth to (already in pgtrgm.html) give the simple hint:
~ is case-sensitive
~* is case-insensitive
In any case a link to functions-matching.html seems indicated.
Yeah, I think there is room for improvements here. Are you up for drafting a
patch for this?
How is this?
(bluntly stating 'similarity comparisons are case-insensitive' -
although I'm not really sure..)
Erik
--
Daniel Gustafsson https://vmware.com/
--- ./doc/src/sgml/pgtrgm.sgml.orig 2022-08-16 14:50:08.586555358 +0200
+++ ./doc/src/sgml/pgtrgm.sgml 2022-08-16 14:56:39.358617804 +0200
@@ -416,6 +416,8 @@
the above-described similarity operators, and additionally support
trigram-based index searches for <literal>LIKE</literal>, <literal>ILIKE</literal>,
<literal>~</literal>, <literal>~*</literal> and <literal>=</literal> queries.
+ The similarity comparisons are case-insensitive, but these queries can be
+ case-sensitive (see <xref linkend="functions-matching"/>).
Inequality operators are not supported.
Note that those indexes may not be as efficient as regular B-tree indexes
for equality operator.
@@ -534,7 +536,8 @@
<para>
Beginning in <productname>PostgreSQL</productname> 9.3, these index types also support
index searches for regular-expression matches
- (<literal>~</literal> and <literal>~*</literal> operators), for example
+ (<literal>~</literal> and <literal>~*</literal> operators, resp. case-sensitive and
+ case-insensitive), for example
<programlisting>
SELECT * FROM test_trgm WHERE t ~ '(foo|bar)';
</programlisting>
