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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >pg_amop</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 9.2.24 Documentation" HREF="index.html"><LINK REL="UP" TITLE="System Catalogs" HREF="catalogs.html"><LINK REL="PREVIOUS" TITLE="pg_am" HREF="catalog-pg-am.html"><LINK REL="NEXT" TITLE="pg_amproc" HREF="catalog-pg-amproc.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="2017-11-06T22:43:11"></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 9.2.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="pg_am" HREF="catalog-pg-am.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="catalogs.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Chapter 45. System Catalogs</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="pg_amproc" HREF="catalog-pg-amproc.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="CATALOG-PG-AMOP" >45.4. <TT CLASS="STRUCTNAME" >pg_amop</TT ></A ></H1 ><P > The catalog <TT CLASS="STRUCTNAME" >pg_amop</TT > stores information about operators associated with access method operator families. There is one row for each operator that is a member of an operator family. A family member can be either a <I CLASS="FIRSTTERM" >search</I > operator or an <I CLASS="FIRSTTERM" >ordering</I > operator. An operator can appear in more than one family, but cannot appear in more than one search position nor more than one ordering position within a family. (It is allowed, though unlikely, for an operator to be used for both search and ordering purposes.) </P ><DIV CLASS="TABLE" ><A NAME="AEN88923" ></A ><P ><B >Table 45-4. <TT CLASS="STRUCTNAME" >pg_amop</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" >amopfamily</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-opfamily.html" ><TT CLASS="STRUCTNAME" >pg_opfamily</TT ></A >.oid</TT ></TD ><TD >The operator family this entry is for</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amoplefttype</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 >Left-hand input data type of operator</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amoprighttype</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 >Right-hand input data type of operator</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amopstrategy</TT ></TD ><TD ><TT CLASS="TYPE" >int2</TT ></TD ><TD > </TD ><TD >Operator strategy number</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amoppurpose</TT ></TD ><TD ><TT CLASS="TYPE" >char</TT ></TD ><TD > </TD ><TD >Operator purpose, either <TT CLASS="LITERAL" >s</TT > for search or <TT CLASS="LITERAL" >o</TT > for ordering</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amopopr</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-operator.html" ><TT CLASS="STRUCTNAME" >pg_operator</TT ></A >.oid</TT ></TD ><TD >OID of the operator</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amopmethod</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 family is for</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >amopsortfamily</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-opfamily.html" ><TT CLASS="STRUCTNAME" >pg_opfamily</TT ></A >.oid</TT ></TD ><TD >The btree operator family this entry sorts according to, if an ordering operator; zero if a search operator</TD ></TR ></TBODY ></TABLE ></DIV ><P > A <SPAN CLASS="QUOTE" >"search"</SPAN > operator entry indicates that an index of this operator family can be searched to find all rows satisfying <TT CLASS="LITERAL" >WHERE</TT > <TT CLASS="REPLACEABLE" ><I >indexed_column</I ></TT > <TT CLASS="REPLACEABLE" ><I >operator</I ></TT > <TT CLASS="REPLACEABLE" ><I >constant</I ></TT >. Obviously, such an operator must return boolean, and its left-hand input type must match the index's column data type. </P ><P > An <SPAN CLASS="QUOTE" >"ordering"</SPAN > operator entry indicates that an index of this operator family can be scanned to return rows in the order represented by <TT CLASS="LITERAL" >ORDER BY</TT > <TT CLASS="REPLACEABLE" ><I >indexed_column</I ></TT > <TT CLASS="REPLACEABLE" ><I >operator</I ></TT > <TT CLASS="REPLACEABLE" ><I >constant</I ></TT >. Such an operator could return any sortable data type, though again its left-hand input type must match the index's column data type. The exact semantics of the <TT CLASS="LITERAL" >ORDER BY</TT > are specified by the <TT CLASS="STRUCTFIELD" >amopsortfamily</TT > column, which must reference a btree operator family for the operator's result type. </P ><DIV CLASS="NOTE" ><BLOCKQUOTE CLASS="NOTE" ><P ><B >Note: </B > At present, it's assumed that the sort order for an ordering operator is the default for the referenced opfamily, i.e., <TT CLASS="LITERAL" >ASC NULLS LAST</TT >. This might someday be relaxed by adding additional columns to specify sort options explicitly. </P ></BLOCKQUOTE ></DIV ><P > An entry's <TT CLASS="STRUCTFIELD" >amopmethod</TT > must match the <TT CLASS="STRUCTNAME" >opfmethod</TT > of its containing operator family (including <TT CLASS="STRUCTFIELD" >amopmethod</TT > here is an intentional denormalization of the catalog structure for performance reasons). Also, <TT CLASS="STRUCTFIELD" >amoplefttype</TT > and <TT CLASS="STRUCTFIELD" >amoprighttype</TT > must match the <TT CLASS="STRUCTFIELD" >oprleft</TT > and <TT CLASS="STRUCTFIELD" >oprright</TT > fields of the referenced <TT CLASS="STRUCTNAME" >pg_operator</TT > entry. </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-am.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-amproc.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><TT CLASS="STRUCTNAME" >pg_am</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_amproc</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >