From 8ee076325f3069787f311fd5c0fcdba7747abef1 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 2 Dec 2007 04:36:40 +0000
Subject: [PATCH] Mention hash opclasses in 'System Dependencies on Operator
Classes', which previously only talked about btree opclasses.
---
doc/src/sgml/xindex.sgml | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/doc/src/sgml/xindex.sgml b/doc/src/sgml/xindex.sgml
index 0e92b3c6552..68d3123ef85 100644
--- a/doc/src/sgml/xindex.sgml
+++ b/doc/src/sgml/xindex.sgml
@@ -1,4 +1,4 @@
-<!-- $PostgreSQL: pgsql/doc/src/sgml/xindex.sgml,v 1.60 2007/04/25 19:48:27 neilc Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/xindex.sgml,v 1.61 2007/12/02 04:36:40 tgl Exp $ -->
<sect1 id="xindex">
<title>Interfacing Extensions To Indexes</title>
@@ -893,6 +893,13 @@ ALTER OPERATOR FAMILY integer_ops USING btree ADD
any assumption about the behavior of operators with particular names.
</para>
</note>
+
+ <para>
+ Another important point is that an operator that
+ appears in a hash operator family is a candidate for hash joins,
+ hash aggregation, and related optimizations. The hash operator family
+ is essential here since it identifies the hash function(s) to use.
+ </para>
</sect2>
<sect2 id="xindex-opclass-features">
@@ -950,7 +957,7 @@ CREATE OPERATOR CLASS polygon_ops
is used. In GIN, the <literal>STORAGE</> type identifies the type of
the <quote>key</> values, which normally is different from the type
of the indexed column — for example, an operator class for
- integer array columns might have keys that are just integers. The
+ integer-array columns might have keys that are just integers. The
GIN <function>extractValue</> and <function>extractQuery</> support
routines are responsible for extracting keys from indexed values.
</para>
--
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