<!--
-$PostgreSQL: pgsql/doc/src/sgml/release.sgml,v 1.381 2005/10/02 23:50:06 tgl Exp $
+$PostgreSQL: pgsql/doc/src/sgml/release.sgml,v 1.382 2005/10/03 01:57:59 momjian Exp $
Typical markup:
<listitem>
<para>
+ <varname>Add proper sequence function dependencies (Tom)
+ </para>
+ <para>
+ In previous releases, <function>nextval()</>,
+ <function>currval</>, and <function>setval()</> recorded
+ sequence names as simple text strings, meaning that renaming or
+ dropping a sequence used in a <command>DEFAULT</> made the
+ clause invalid. This release stores all newly-created sequence
+ function arguments using internal oids, allowing them to handle
+ sequence renaming, and adding dependency information that
+ </para>
+ </listitem>
+
+ <listitem>
+ <para>
<varname>add_missing_from</> is now false by default (Neil)
</para>
<para>
</para>
<para>
When an expression like <literal>nextval('myseq')</> appears in a
- column default expression or view, the referenced sequence (here
- <literal>myseq</>) is now looked up immediately, and its pg_class
- OID is placed in the stored expression. This representation will
- survive renaming of the referenced sequence, as well as changes in
- schema search paths. The system also understands that the sequence
- reference represents a dependency, so the sequence cannot be dropped
- without dropping the referencing object. To get the old behavior of
- run-time lookup of the sequence by name, cast the argument to
- <type>text</>, for example <literal>nextval('myseq'::text)</>.
+ column <command>DEFAULT</> expression or view, the referenced
+ sequence (here <literal>myseq</>) is now looked up immediately,
+ and its pg_class OID is placed in the stored expression. This
+ representation will survive renaming of the referenced sequence,
+ as well as changes in schema search paths. The system also
+ understands that the sequence reference represents a dependency,
+ so the sequence cannot be dropped without dropping the
+ referencing object. Previous releases stored this information as
+ a simple text string, with none of the benefits outlined above.
+ To get the old text-based behavior of run-time lookup of the
+ sequence name, cast the argument to <type>text</>, for example
+ <literal>nextval('myseq'::text)</>.
</para>
+ <para>
+ Pre-8.1 schemas loaded into 8.1 will use the previous, text-based
+ representation and therefore will not have these protections.
+ However, it is possible to upgrade a database to the newer
+ OID-based arguments. First, save this query into a file, such as
+ <filename>fixseq.sql</>:
+<programlisting>
+SELECT 'ALTER TABLE ' ||
+ pg_catalog.quote_ident(n.nspname) || '.' ||
+ pg_catalog.quote_ident(c.relname) ||
+ ' ALTER COLUMN ' || pg_catalog.quote_ident(a.attname) ||
+ ' SET DEFAULT ' ||
+ regexp_replace(d.adsrc, '(nextval\\(''[^'']*'')::text', '\\1', 'g') ||
+ ';'
+FROM pg_namespace n, pg_class c, pg_attribute a, pg_attrdef d
+WHERE n.oid = c.relnamespace AND
+ c.oid = a.attrelid AND
+ a.attrelid = d.adrelid AND
+ a.attnum = d.adnum AND
+ d.adsrc ~ '.*nextval\\(''[^'']*''::text';
+</programlisting>
+ Next, run the query against a database to find what
+ adjustments are required, like this for database <literal>db1</>:
+<programlisting>
+psql -aT -f fixseq.sql db1
+</programlisting>
+ This will show the <command>ALTER TABLE</> commands needed to
+ convert the database to the newer OID-based representation.
+ Finally, run this to update the database:
+<programlisting>
+psql -aT -f fixseq.sql db1 | psql -e db1
+</programlisting>
+ This process should be done for each database loaded with pre-8.1
+ schemas.
</listitem>
<listitem>