From 710d90da1fd8c1d028215ecaf7402062079e99e9 Mon Sep 17 00:00:00 2001
From: Teodor Sigaev <teodor@sigaev.ru>
Date: Tue, 3 Apr 2018 19:46:45 +0300
Subject: Add prefix operator for TEXT type.

The prefix operator along with SP-GiST indexes can be used as an alternative
for LIKE 'word%' commands  and it doesn't have a limitation of string/prefix
length as B-Tree has.

Bump catalog version

Author: Ildus Kurbangaliev with some editorization by me
Review by: Arthur Zakirov, Alexander Korotkov, and me
Discussion: https://www.postgresql.org/message-id/flat/20180202180327.222b04b3@wp.localdomain
---
 doc/src/sgml/func.sgml   | 21 +++++++++++++++++++++
 doc/src/sgml/spgist.sgml |  1 +
 2 files changed, 22 insertions(+)

(limited to 'doc/src')

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 5abb1c46fbb..9a1efc14cf7 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -2274,6 +2274,21 @@
        <entry><literal>ph</literal></entry>
       </row>
 
+      <row>
+       <entry>
+        <indexterm>
+         <primary>starts_with</primary>
+        </indexterm>
+        <literal><function>starts_with(<parameter>string</parameter>, <parameter>prefix</parameter>)</function></literal>
+       </entry>
+       <entry><type>bool</type></entry>
+       <entry>
+        Returns true if <parameter>string</parameter> starts with <parameter>prefix</parameter>.
+       </entry>
+       <entry><literal>starts_with('alphabet', 'alph')</literal></entry>
+       <entry><literal>t</literal></entry>
+      </row>
+
       <row>
        <entry>
         <indexterm>
@@ -4033,6 +4048,12 @@ cast(-44 as bit(12))           <lineannotation>111111010100</lineannotation>
     ILIKE</function>, respectively.  All of these operators are
     <productname>PostgreSQL</productname>-specific.
    </para>
+
+   <para>
+    There is also the prefix operator <literal>^@</literal> and corresponding
+    <function>starts_with</function> function which covers cases when only
+    searching by beginning of the string is needed.
+   </para>
   </sect2>
 
 
diff --git a/doc/src/sgml/spgist.sgml b/doc/src/sgml/spgist.sgml
index e47f70be89b..06b75190522 100644
--- a/doc/src/sgml/spgist.sgml
+++ b/doc/src/sgml/spgist.sgml
@@ -161,6 +161,7 @@
        <literal>~&lt;~</literal>
        <literal>~&gt;=~</literal>
        <literal>~&gt;~</literal>
+       <literal>^@</literal>
       </entry>
      </row>
      <row>
-- 
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