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| -rw-r--r-- | doc/src/sgml/indices.sgml | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/doc/src/sgml/indices.sgml b/doc/src/sgml/indices.sgml index 5fa1e79fefb..9bb19c2cee0 100644 --- a/doc/src/sgml/indices.sgml +++ b/doc/src/sgml/indices.sgml @@ -1,4 +1,4 @@ -<!-- $PostgreSQL: pgsql/doc/src/sgml/indices.sgml,v 1.55 2005/11/07 17:36:44 tgl Exp $ --> +<!-- $PostgreSQL: pgsql/doc/src/sgml/indices.sgml,v 1.56 2006/01/18 21:29:45 momjian Exp $ --> <chapter id="indexes"> <title id="indexes-title">Indexes</title> @@ -141,17 +141,21 @@ CREATE INDEX test1_id_index ON test1 (id); <para> The optimizer can also use a B-tree index for queries involving the - pattern matching operators <literal>LIKE</>, - <literal>ILIKE</literal>, <literal>~</literal>, and - <literal>~*</literal>, <emphasis>if</emphasis> the pattern is a constant - and is anchored to the beginning of the string — for example, - <literal>col LIKE 'foo%'</literal> or <literal>col ~ '^foo'</literal>, - but not <literal>col LIKE '%bar'</literal>. However, if your server does - not use the C locale you will need to create the index with a - special operator class to support indexing of pattern-matching queries. - See <xref linkend="indexes-opclass"> below. + pattern matching operators <literal>LIKE</> and <literal>~</literal> + <emphasis>if</emphasis> the pattern is a constant and is anchored to + the beginning of the string — for example, <literal>col LIKE + 'foo%'</literal> or <literal>col ~ '^foo'</literal>, but not + <literal>col LIKE '%bar'</literal>. However, if your server does not + use the C locale you will need to create the index with a special + operator class to support indexing of pattern-matching queries. See + <xref linkend="indexes-opclass"> below. It is also possible to use + B-tree indexes for <literal>ILIKE</literal> and + <literal>~*</literal>, but only if the pattern starts with + non-alphabetic characters, i.e. characters that are not affected by + upper/lower case conversion. </para> + <para> <indexterm> <primary>index</primary> |