<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >pg_class</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 9.2.13 Documentation" HREF="index.html"><LINK REL="UP" TITLE="System Catalogs" HREF="catalogs.html"><LINK REL="PREVIOUS" TITLE="pg_cast" HREF="catalog-pg-cast.html"><LINK REL="NEXT" TITLE="pg_constraint" HREF="catalog-pg-constraint.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="2015-06-13T20:07:41"></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 9.2.13 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="pg_cast" HREF="catalog-pg-cast.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_constraint" HREF="catalog-pg-constraint.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="CATALOG-PG-CLASS" >45.11. <TT CLASS="STRUCTNAME" >pg_class</TT ></A ></H1 ><P > The catalog <TT CLASS="STRUCTNAME" >pg_class</TT > catalogs tables and most everything else that has columns or is otherwise similar to a table. This includes indexes (but see also <TT CLASS="STRUCTNAME" >pg_index</TT >), sequences, views, composite types, and TOAST tables; see <TT CLASS="STRUCTFIELD" >relkind</TT >. Below, when we mean all of these kinds of objects we speak of <SPAN CLASS="QUOTE" >"relations"</SPAN >. Not all columns are meaningful for all relation types. </P ><DIV CLASS="TABLE" ><A NAME="AEN89259" ></A ><P ><B >Table 45-11. <TT CLASS="STRUCTNAME" >pg_class</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" >relname</TT ></TD ><TD ><TT CLASS="TYPE" >name</TT ></TD ><TD > </TD ><TD >Name of the table, index, view, etc.</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relnamespace</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 > The OID of the namespace that contains this relation </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reltype</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 > The OID of the data type that corresponds to this table's row type, if any (zero for indexes, which have no <TT CLASS="STRUCTNAME" >pg_type</TT > entry) </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reloftype</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 > For typed tables, the OID of the underlying composite type, zero for all other relations </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relowner</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-authid.html" ><TT CLASS="STRUCTNAME" >pg_authid</TT ></A >.oid</TT ></TD ><TD >Owner of the relation</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relam</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 >If this is an index, the access method used (B-tree, hash, etc.)</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relfilenode</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD > </TD ><TD >Name of the on-disk file of this relation; zero means this is a <SPAN CLASS="QUOTE" >"mapped"</SPAN > relation whose disk file name is determined by low-level state</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reltablespace</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-tablespace.html" ><TT CLASS="STRUCTNAME" >pg_tablespace</TT ></A >.oid</TT ></TD ><TD > The tablespace in which this relation is stored. If zero, the database's default tablespace is implied. (Not meaningful if the relation has no on-disk file.) </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relpages</TT ></TD ><TD ><TT CLASS="TYPE" >int4</TT ></TD ><TD > </TD ><TD > Size of the on-disk representation of this table in pages (of size <TT CLASS="SYMBOL" >BLCKSZ</TT >). This is only an estimate used by the planner. It is updated by <TT CLASS="COMMAND" >VACUUM</TT >, <TT CLASS="COMMAND" >ANALYZE</TT >, and a few DDL commands such as <TT CLASS="COMMAND" >CREATE INDEX</TT >. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reltuples</TT ></TD ><TD ><TT CLASS="TYPE" >float4</TT ></TD ><TD > </TD ><TD > Number of rows in the table. This is only an estimate used by the planner. It is updated by <TT CLASS="COMMAND" >VACUUM</TT >, <TT CLASS="COMMAND" >ANALYZE</TT >, and a few DDL commands such as <TT CLASS="COMMAND" >CREATE INDEX</TT >. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relallvisible</TT ></TD ><TD ><TT CLASS="TYPE" >int4</TT ></TD ><TD > </TD ><TD > Number of pages that are marked all-visible in the table's visibility map. This is only an estimate used by the planner. It is updated by <TT CLASS="COMMAND" >VACUUM</TT >, <TT CLASS="COMMAND" >ANALYZE</TT >, and a few DDL commands such as <TT CLASS="COMMAND" >CREATE INDEX</TT >. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reltoastrelid</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-class.html" ><TT CLASS="STRUCTNAME" >pg_class</TT ></A >.oid</TT ></TD ><TD > OID of the TOAST table associated with this table, 0 if none. The TOAST table stores large attributes <SPAN CLASS="QUOTE" >"out of line"</SPAN > in a secondary table. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reltoastidxid</TT ></TD ><TD ><TT CLASS="TYPE" >oid</TT ></TD ><TD ><TT CLASS="LITERAL" ><A HREF="catalog-pg-class.html" ><TT CLASS="STRUCTNAME" >pg_class</TT ></A >.oid</TT ></TD ><TD > For a TOAST table, the OID of its index. 0 if not a TOAST table. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relhasindex</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD > True if this is a table and it has (or recently had) any indexes </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relisshared</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD > True if this table is shared across all databases in the cluster. Only certain system catalogs (such as <TT CLASS="STRUCTNAME" >pg_database</TT >) are shared. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relpersistence</TT ></TD ><TD ><TT CLASS="TYPE" >char</TT ></TD ><TD > </TD ><TD > <TT CLASS="LITERAL" >p</TT > = permanent table, <TT CLASS="LITERAL" >u</TT > = unlogged table, <TT CLASS="LITERAL" >t</TT > = temporary table </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relkind</TT ></TD ><TD ><TT CLASS="TYPE" >char</TT ></TD ><TD > </TD ><TD > <TT CLASS="LITERAL" >r</TT > = ordinary table, <TT CLASS="LITERAL" >i</TT > = index, <TT CLASS="LITERAL" >S</TT > = sequence, <TT CLASS="LITERAL" >v</TT > = view, <TT CLASS="LITERAL" >c</TT > = composite type, <TT CLASS="LITERAL" >t</TT > = TOAST table, <TT CLASS="LITERAL" >f</TT > = foreign table </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relnatts</TT ></TD ><TD ><TT CLASS="TYPE" >int2</TT ></TD ><TD > </TD ><TD > Number of user columns in the relation (system columns not counted). There must be this many corresponding entries in <TT CLASS="STRUCTNAME" >pg_attribute</TT >. See also <TT CLASS="LITERAL" >pg_attribute.attnum</TT >. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relchecks</TT ></TD ><TD ><TT CLASS="TYPE" >int2</TT ></TD ><TD > </TD ><TD > Number of <TT CLASS="LITERAL" >CHECK</TT > constraints on the table; see <A HREF="catalog-pg-constraint.html" ><TT CLASS="STRUCTNAME" >pg_constraint</TT ></A > catalog </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relhasoids</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD > True if we generate an OID for each row of the relation </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relhaspkey</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD > True if the table has (or once had) a primary key </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relhasrules</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD > True if table has (or once had) rules; see <A HREF="catalog-pg-rewrite.html" ><TT CLASS="STRUCTNAME" >pg_rewrite</TT ></A > catalog </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relhastriggers</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD > True if table has (or once had) triggers; see <A HREF="catalog-pg-trigger.html" ><TT CLASS="STRUCTNAME" >pg_trigger</TT ></A > catalog </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relhassubclass</TT ></TD ><TD ><TT CLASS="TYPE" >bool</TT ></TD ><TD > </TD ><TD >True if table has (or once had) any inheritance children</TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relfrozenxid</TT ></TD ><TD ><TT CLASS="TYPE" >xid</TT ></TD ><TD > </TD ><TD > All transaction IDs before this one have been replaced with a permanent (<SPAN CLASS="QUOTE" >"frozen"</SPAN >) transaction ID in this table. This is used to track whether the table needs to be vacuumed in order to prevent transaction ID wraparound or to allow <TT CLASS="LITERAL" >pg_clog</TT > to be shrunk. Zero (<TT CLASS="SYMBOL" >InvalidTransactionId</TT >) if the relation is not a table. </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >relacl</TT ></TD ><TD ><TT CLASS="TYPE" >aclitem[]</TT ></TD ><TD > </TD ><TD > Access privileges; see <A HREF="sql-grant.html" >GRANT</A > and <A HREF="sql-revoke.html" >REVOKE</A > for details </TD ></TR ><TR ><TD ><TT CLASS="STRUCTFIELD" >reloptions</TT ></TD ><TD ><TT CLASS="TYPE" >text[]</TT ></TD ><TD > </TD ><TD > Access-method-specific options, as <SPAN CLASS="QUOTE" >"keyword=value"</SPAN > strings </TD ></TR ></TBODY ></TABLE ></DIV ><P > Several of the Boolean flags in <TT CLASS="STRUCTNAME" >pg_class</TT > are maintained lazily: they are guaranteed to be true if that's the correct state, but may not be reset to false immediately when the condition is no longer true. For example, <TT CLASS="STRUCTFIELD" >relhasindex</TT > is set by <TT CLASS="COMMAND" >CREATE INDEX</TT >, but it is never cleared by <TT CLASS="COMMAND" >DROP INDEX</TT >. Instead, <TT CLASS="COMMAND" >VACUUM</TT > clears <TT CLASS="STRUCTFIELD" >relhasindex</TT > if it finds the table has no indexes. This arrangement avoids race conditions and improves concurrency. </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-cast.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-constraint.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><TT CLASS="STRUCTNAME" >pg_cast</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_constraint</TT ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >