diff options
Diffstat (limited to 'doc/src')
| -rw-r--r-- | doc/src/sgml/datatype.sgml | 42 | ||||
| -rw-r--r-- | doc/src/sgml/release.sgml | 3 |
2 files changed, 26 insertions, 19 deletions
diff --git a/doc/src/sgml/datatype.sgml b/doc/src/sgml/datatype.sgml index bf53769a1e0..aa4e25ccb60 100644 --- a/doc/src/sgml/datatype.sgml +++ b/doc/src/sgml/datatype.sgml @@ -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> diff --git a/doc/src/sgml/release.sgml b/doc/src/sgml/release.sgml index 9bfc6de17b0..1878fd356ef 100644 --- a/doc/src/sgml/release.sgml +++ b/doc/src/sgml/release.sgml @@ -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 |