<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >Introduction</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 9.0.15 Documentation" HREF="index.html"><LINK REL="UP" TITLE="GIN Indexes" HREF="gin.html"><LINK REL="PREVIOUS" TITLE="GIN Indexes" HREF="gin.html"><LINK REL="NEXT" TITLE="Extensibility" HREF="gin-extensibility.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2014-01-24T13:16:52"></HEAD ><BODY CLASS="SECT1" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" ><A HREF="index.html" >PostgreSQL 9.0.15 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="GIN Indexes" HREF="gin.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="gin.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 53. GIN Indexes</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="Extensibility" HREF="gin-extensibility.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="GIN-INTRO" >53.1. Introduction</A ></H1 ><P > <ACRONYM CLASS="ACRONYM" >GIN</ACRONYM > stands for Generalized Inverted Index. It is an index structure storing a set of (key, posting list) pairs, where a <SPAN CLASS="QUOTE" >"posting list"</SPAN > is a set of rows in which the key occurs. Each indexed value can contain many keys, so the same row ID can appear in multiple posting lists. </P ><P > It is generalized in the sense that a <ACRONYM CLASS="ACRONYM" >GIN</ACRONYM > index does not need to be aware of the operation that it accelerates. Instead, it uses custom strategies defined for particular data types. </P ><P > One advantage of <ACRONYM CLASS="ACRONYM" >GIN</ACRONYM > is that it allows the development of custom data types with the appropriate access methods, by an expert in the domain of the data type, rather than a database expert. This is much the same advantage as using <ACRONYM CLASS="ACRONYM" >GiST</ACRONYM >. </P ><P > The <ACRONYM CLASS="ACRONYM" >GIN</ACRONYM > implementation in <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN > is primarily maintained by Teodor Sigaev and Oleg Bartunov. There is more information about <ACRONYM CLASS="ACRONYM" >GIN</ACRONYM > on their <A HREF="http://www.sai.msu.su/~megera/wiki/Gin" TARGET="_top" >website</A >. </P ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="gin.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="gin-extensibility.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >GIN Indexes</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="gin.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >Extensibility</TD ></TR ></TABLE ></DIV ></BODY ></HTML >