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Document problems with hash indexes compared to btree.

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This commit is contained in:
Bruce Momjian
2002-06-21 03:25:53 +00:00
parent db650b451e
commit ebe4375fa1
3 changed files with 14 additions and 12 deletions
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7
doc/src/sgml/ref/create_index.sgml
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@@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_index.sgml,v 1.31 2002/05/18 15:44:47 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_index.sgml,v 1.32 2002/06/21 03:25:53 momjian Exp $
PostgreSQL documentation
-->
@@ -329,6 +329,11 @@ ERROR: Cannot create index: 'index_name' already exists.
an indexed attribute is involved in a comparison using
the <literal>=</literal> operator.
</para>
<para>
Testing has shown that hash indexes are slower than btree indexes,
and the size and build time for hash indexes is much worse. For
these reasons, hash index use is discouraged.
</para>
<para>
Currently, only the B-tree and gist access methods support multicolumn