<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.58 2006/07/02 01:58:36 momjian Exp $ -->

<!-- $PostgreSQL: pgsql/doc/src/sgml/ddl.sgml,v 1.59 2006/07/03 16:43:14 tgl Exp $ -->

<chapter id="ddl">

<title>Data Definition</title>

parent. Similarly an inheritance link can be removed from a child using the

<command>ALTER TABLE</command> using the <command>NO INHERIT</command>

subform.

</para>

<para>

One convenient way to create a compatible table to be a new child is using

caveat below regarding constraints). Alternatively a compatible table can

be created by first creating a new child using <command>CREATE

TABLE</command> then removing the inheritance link with <command>ALTER

TABLE</command>. </para>

TABLE</command>.

</para>

<para>

A parent table cannot be dropped while any

be accessed for a query. Whereas the alternative, adding those columns

to every index, increases space usage which can erase any

performance gain.

<para>

</para>

<para>

When most of the heavily accessed area of the table is in a single