From 1e16a8107db9a50435b39e09c6f9c52c45e63e1a Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 10 Apr 2011 18:02:17 -0400
Subject: Teach regular expression operators to honor collations.

This involves getting the character classification and case-folding
functions in the regex library to use the collations infrastructure.
Most of this work had been done already in connection with the upper/lower
and LIKE logic, so it was a simple matter of transposition.

While at it, split out these functions into a separate source file
regc_pg_locale.c, so that they can be correctly labeled with the Postgres
project's license rather than the Scriptics license.  These functions are
100% Postgres-written code whereas what remains in regc_locale.c is still
mostly not ours, so lumping them both under the same copyright notice was
getting more and more misleading.
---
 doc/src/sgml/charset.sgml | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

(limited to 'doc/src')

diff --git a/doc/src/sgml/charset.sgml b/doc/src/sgml/charset.sgml
index 72ba3337902..6b0793e2197 100644
--- a/doc/src/sgml/charset.sgml
+++ b/doc/src/sgml/charset.sgml
@@ -221,17 +221,21 @@ initdb --locale=sv_SE
 
      <listitem>
       <para>
-       The ability to use indexes with <literal>LIKE</> clauses
-       <indexterm><primary>LIKE</><secondary>and locales</></indexterm>
+       The <function>upper</>, <function>lower</>, and <function>initcap</>
+       functions
+       <indexterm><primary>upper</><secondary>and locales</></indexterm>
+       <indexterm><primary>lower</><secondary>and locales</></indexterm>
       </para>
      </listitem>
 
      <listitem>
       <para>
-       The <function>upper</>,  <function>lower</>,  and <function>initcap</>
-       functions
-       <indexterm><primary>upper</><secondary>and locales</></indexterm>
-       <indexterm><primary>lower</><secondary>and locales</></indexterm>
+       Pattern matching operators (<literal>LIKE</>, <literal>SIMILAR TO</>,
+       and POSIX-style regular expressions); locales affect both case
+       insensitive matching and the classification of characters by
+       character-class regular expressions
+       <indexterm><primary>LIKE</><secondary>and locales</></indexterm>
+       <indexterm><primary>regular expressions</><secondary>and locales</></indexterm>
       </para>
      </listitem>
 
@@ -241,6 +245,12 @@ initdb --locale=sv_SE
        <indexterm><primary>to_char</><secondary>and locales</></indexterm>
       </para>
      </listitem>
+
+     <listitem>
+      <para>
+       The ability to use indexes with <literal>LIKE</> clauses
+      </para>
+     </listitem>
     </itemizedlist>
    </para>
 
@@ -319,8 +329,8 @@ initdb --locale=sv_SE
   <indexterm zone="collation"><primary>collation</></>
 
   <para>
-   The collation feature allows specifying the sort order and certain
-   other locale aspects of data per-column, or even per-operation.
+   The collation feature allows specifying the sort order and character
+   classification behavior of data per-column, or even per-operation.
    This alleviates the restriction that the
    <symbol>LC_COLLATE</symbol> and <symbol>LC_CTYPE</symbol> settings
    of a database cannot be changed after its creation.
@@ -351,8 +361,8 @@ initdb --locale=sv_SE
    </para>
 
    <para>
-    When the database system has to perform an ordering or a
-    comparison, it uses the collation of the input expression.  This
+    When the database system has to perform an ordering or a character
+    classification, it uses the collation of the input expression.  This
     happens, for example, with <literal>ORDER BY</literal> clauses
     and function or operator calls such as <literal>&lt;</literal>.
     The collation to apply for an <literal>ORDER BY</literal> clause
@@ -361,7 +371,8 @@ initdb --locale=sv_SE
     below.  In addition to comparison operators, collations are taken into
     account by functions that convert between lower and upper case
     letters, such as <function>lower</>, <function>upper</>, and
-    <function>initcap</>.
+    <function>initcap</>; by pattern matching operators; and by
+    <function>to_char</> and related functions.
    </para>
 
    <para>
-- 
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