There is a sentence in btree.sgml:
<productname>PostgreSQL</productname> includes an implementation of the
standard <acronym>btree</acronym> (multi-way binary tree) index data
structure.
I think the term "btree" here means "multi-way balanced tree", rather
than "multi-way binary tree". In fact in our btree, there could be
more than one key in a node. Patch attached.
Best regards,
--
Tatsuo Ishii
SRA OSS, Inc. Japan
English: http://www.sraoss.co.jp/index_en.php
Japanese:http://www.sraoss.co.jp
diff --git a/doc/src/sgml/btree.sgml b/doc/src/sgml/btree.sgml
index c16825e2ea..996932e35d 100644
--- a/doc/src/sgml/btree.sgml
+++ b/doc/src/sgml/btree.sgml
@@ -13,7 +13,7 @@
<para>
<productname>PostgreSQL</productname> includes an implementation of the
- standard <acronym>btree</acronym> (multi-way binary tree) index data
+ standard <acronym>btree</acronym> (multi-way balanced tree) index data
structure. Any data type that can be sorted into a well-defined linear
order can be indexed by a btree index. The only limitation is that an
index entry cannot exceed approximately one-third of a page (after TOAST