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: http://www.sai.msu.su/~megera/wiki/relation_featur%C5s/DB/btree_gin
Дата изменения: Unknown Дата индексирования: Mon Apr 11 09:05:44 2016 Кодировка: |
Teodor Sigaev and Oleg Bartunov <!-- $PostgreSQL: pgsql/doc/src/sgml/btree-gin.sgml,v 1.1 2009/03/25 23:20:01 tgl Exp $ --> <sect1 id="btree-gin"> <title>btree_gin</title> <indexterm zone="btree-gin"> <primary>btree_gin</primary> </indexterm> <para> <filename>btree_gin</> provides sample GIN operator classes that implement B-Tree equivalent behavior for the data types <type>int2</>, <type>int4</>, <type>int8</>, <type>float4</>, <type>float8</>, <type>timestamp with time zone</>, <type>timestamp without time zone</>, <type>time with time zone</>, <type>time without time zone</>, <type>date</>, <type>interval</>, <type>oid</>, <type>money</>, <type>"char"</>, <type>varchar</>, <type>text</>, <type>bytea</>, <type>bit</>, <type>varbit</>, <type>macaddr</>, <type>inet</>, and <type>cidr</>. </para> <para> In general, these operator classes will not outperform the equivalent standard btree index methods, and they lack one major feature of the standard btree code: the ability to enforce uniqueness. However, they are useful for GIN testing and as a base for developing other GIN operator classes. Also, for queries that test both a GIN-indexable column and a btree-indexable column, it might be more efficient to create a multi-column GIN index that uses one of these opclasses than to create two separate indexes that would have to be combined via bitmap ANDing. </para> <sect2> <title>Example usage</title> <programlisting> CREATE TABLE test (a int4); -- create index CREATE INDEX testidx ON test USING gin (a); -- query SELECT * FROM test WHERE a < 10; </programlisting> </sect2> <sect2> <title>Authors</title> <para> Teodor Sigaev (<email>teodor@stack.net</email>) and Oleg Bartunov (<email>oleg@sai.msu.su</email>). See <ulink url="http://www.sai.msu.su/~megera/oddmuse/index.cgi/Gin"></ulink> for additional information. </para> </sect2> </sect1>