[doc] improve tableoid description
Hi
Attached patch aims to improve the description of the tableoid system column [1]
by:
- mentioning it's useful for determining table names for partitioned tables as
well as for those in inheritance hierarchies
- mentioning the possibility of casting tableoid to regclass (which is simpler
than the currently suggested join on pg_class, which is only needed if
the schema name is absolutely required)
[1] https://www.postgresql.org/docs/current/ddl-system-columns.html
Regards
Ian Barwick
--
EnterpriseDB: https://www.enterprisedb.com
diff --git a/doc/src/sgml/ddl.sgml b/doc/src/sgml/ddl.sgml
index c4897d68c9..f916f0bd70 100644
--- a/doc/src/sgml/ddl.sgml
+++ b/doc/src/sgml/ddl.sgml
@@ -1144,12 +1144,18 @@ CREATE TABLE circles (
<para>
The OID of the table containing this row. This column is
- particularly handy for queries that select from inheritance
+ particularly handy for queries that select from partitioned
+ tables (see <xref linkend="ddl-partitioning"/>) or inheritance
hierarchies (see <xref linkend="ddl-inherit"/>), since without it,
it's difficult to tell which individual table a row came from. The
- <structfield>tableoid</structfield> can be joined against the
+ <structfield>tableoid</structfield> can be cast to <type>regclass</type>
+ to obtain the table name. However the table's schema will only be shown
+ if the table is <emphasis>not</emphasis> in the default path, otherwise
+ <structfield>tableoid</structfield> will need to be joined against the
<structfield>oid</structfield> column of
- <structname>pg_class</structname> to obtain the table name.
+ <link linkend="catalog-pg-class"><structname>pg_class</structname></link>
+ to obtain the <structfield>relnamespace</structfield> OID (which itself
+ can be cast to <type>regnamespace</type> to obtain the schema name).
</para>
</listitem>
</varlistentry>
