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Fix pg_dump to dump serial columns as serials. Per pghackers discussion,

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cause SERIAL column declaration not to imply UNIQUE, so that this can be
done without creating an extra index.
This commit is contained in:
Tom Lane
2002-08-19 19:33:36 +00:00
parent 6ebc90b045
commit a0bf1a7f2e
8 changed files with 249 additions and 100 deletions
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42
doc/src/sgml/datatype.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.98 2002/08/13 20:40:43 momjian Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.99 2002/08/19 19:33:33 tgl Exp $
-->
<chapter id="datatype">
@ -665,14 +665,17 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (
<programlisting>
CREATE SEQUENCE <replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq;
CREATE TABLE <replaceable class="parameter">tablename</replaceable> (
<replaceable class="parameter">colname</replaceable> integer DEFAULT nextval('<replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq') UNIQUE NOT NULL
<replaceable class="parameter">colname</replaceable> integer DEFAULT nextval('<replaceable class="parameter">tablename</replaceable>_<replaceable class="parameter">colname</replaceable>_seq') NOT NULL
);
</programlisting>
Thus, we have created an integer column and arranged for its default
values to be assigned from a sequence generator. UNIQUE and NOT NULL
constraints are applied to ensure that explicitly-inserted values
will never be duplicates, either.
values to be assigned from a sequence generator. A <literal>NOT NULL</>
constraint is applied to ensure that a NULL value cannot be explicitly
inserted, either. In most cases you would also want to attach a
<literal>UNIQUE</> or <literal>PRIMARY KEY</> constraint to prevent
duplicate values from being inserted by accident, but this is
not automatic.
</para>
<para>
@ -685,20 +688,23 @@ CREATE TABLE <replaceable class="parameter">tablename</replaceable> (
</para>
<para>
Implicit sequences supporting the <type>serial</type> types are
not automatically dropped when a table containing a serial type
is dropped. So, the following commands executed in order will likely fail:
<programlisting>
CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceable class="parameter">colname</replaceable> SERIAL);
DROP TABLE <replaceable class="parameter">tablename</replaceable>;
CREATE TABLE <replaceable class="parameter">tablename</replaceable> (<replaceable class="parameter">colname</replaceable> SERIAL);
</programlisting>
The sequence will remain in the database until explicitly dropped using
<command>DROP SEQUENCE</command>. (This annoyance will probably be
fixed in some future release.)
The sequence created by a <type>serial</type> type is automatically
dropped when
the owning column is dropped, and cannot be dropped otherwise.
(This was not true in <productname>PostgreSQL</productname> releases
before 7.3. Note that this automatic drop linkage will not occur for a
sequence created by reloading a dump from a pre-7.3 database; the dump
file does not contain the information needed to establish the dependency
link.)
</para>
<note><para>
Prior to <productname>PostgreSQL</productname> 7.3, <type>serial</type>
implied <literal>UNIQUE</literal>. This is no longer automatic. If
you wish a serial column to be <literal>UNIQUE</literal> or a
<literal>PRIMARY KEY</literal> it must now be specified, same as with
any other datatype.
</para></note>
</sect2>
</sect1>

3
doc/src/sgml/release.sgml
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@ -1,5 +1,5 @@
<!--
$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.147 2002/08/18 09:36:25 petere Exp $
$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.148 2002/08/19 19:33:34 tgl Exp $
-->
<appendix id="release">
@ -24,6 +24,7 @@ CDATA means the content is "SGML-free", so you can write without
worries about funny characters.
-->
<literallayout><![CDATA[
SERIAL no longer implies UNIQUE; specify explicitly if index is wanted
pg_dump -n and -N options have been removed. The new behavior is like -n but knows about key words.
CLUSTER is no longer hazardous to your schema
COPY accepts a list of columns to copy