<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >pg_opclass</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 8.0.11 Documentation" HREF="index.html"><LINK REL="UP" TITLE="System Catalogs" HREF="catalogs.html"><LINK REL="PREVIOUS" TITLE="pg_namespace" HREF="catalog-pg-namespace.html"><LINK REL="NEXT" TITLE="pg_operator" HREF="catalog-pg-operator.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="2007-02-02T03:57:22"></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" >PostgreSQL 8.0.11 Documentation</TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="catalog-pg-namespace.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="catalogs.html" >Fast Backward</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 41. System Catalogs</TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="catalogs.html" >Fast Forward</A ></TD ><TD WIDTH="10%" ALIGN="right" VALIGN="top" ><A HREF="catalog-pg-operator.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="CATALOG-PG-OPCLASS" >41.22. <TT CLASS="STRUCTNAME" >pg_opclass</TT ></A ></H1 ><A NAME="AEN53875" ></A ><P > The catalog <TT CLASS="STRUCTNAME" >pg_opclass</TT > defines index access method operator classes. Each operator class defines semantics for index columns of a particular data type and a particular index access method. Note that there can be multiple operator classes for a given data type/access method combination, thus supporting multiple behaviors. </P ><P > Operator classes are described at length in <A HREF="xindex.html" >Section 31.14</A >. </P ><DIV CLASS="TABLE" ><A NAME="AEN53881" ></A ><P ><B >Table 41-22. <TT CLASS="STRUCTNAME" >pg_opclass</TT > Columns</B ></P ><TABLE BORDER="1" CLASS="CALSTABLE" ><COL><COL><COL><COL><THEAD ><TR ><TH >Name</TH ><TH >Type</TH ><TH >References</TH ><TH >Description</TH ></TR ></THEAD ><TBODY ><TR ><TD ><TT CLASS="STRUCTFIELD" >opcamid</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-am.html" ><TT CLASS="STRUCTNAME" >pg_am</TT ></A >.oid</TT ></TD ><TD >Index access method operator class is for</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >opcname</TT ></TD ><TD ><TT CLASS="TYPE" >name</TT ></TD ><TD > </TD ><TD >Name of this operator class</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >opcnamespace</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-namespace.html" ><TT CLASS="STRUCTNAME" >pg_namespace</TT ></A >.oid</TT ></TD ><TD >Namespace of this operator class</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >opcowner</TT ></TD ><TD ><TT CLASS="TYPE" >int4</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-shadow.html" ><TT CLASS="STRUCTNAME" >pg_shadow</TT ></A >.usesysid</TT ></TD ><TD >Operator class owner</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >opcintype</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-type.html" ><TT CLASS="STRUCTNAME" >pg_type</TT ></A >.oid</TT ></TD ><TD >Data type that the operator class indexes</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >opcdefault</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD >True if this operator class is the default for <TT CLASS="STRUCTFIELD" >opcintype</TT ></TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >opckeytype</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-type.html" ><TT CLASS="STRUCTNAME" >pg_type</TT ></A >.oid</TT ></TD ><TD >Type of data stored in index, or zero if same as <TT CLASS="STRUCTFIELD" >opcintype</TT ></TD ></TR ></TBODY ></TABLE ></DIV ><P > The majority of the information defining an operator class is actually not in its <TT CLASS="STRUCTNAME" >pg_opclass</TT > row, but in the associated rows in <TT CLASS="STRUCTNAME" >pg_amop</TT > and <TT CLASS="STRUCTNAME" >pg_amproc</TT >. Those rows are considered to be part of the operator class definition — this is not unlike the way that a relation is defined by a single <TT CLASS="STRUCTNAME" >pg_class</TT > row plus associated rows in <TT CLASS="STRUCTNAME" >pg_attribute</TT > and other tables. </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="catalog-pg-namespace.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="catalog-pg-operator.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><TT CLASS="STRUCTNAME" >pg_namespace</TT ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="catalogs.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><TT CLASS="STRUCTNAME" >pg_operator</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >