Here is my much-promised patch to let people add UNIQUE constraints after

table creation time.  Big deal you say - but this patch is the basis of the
next thing which is adding PRIMARY KEYs after table creation time.  (Which
is currently impossible without twiddling catalogs)

Rundown
-------

* I have made the makeObjectName function of analyze.c non-static, and
exported it in analyze.h

* I have included analyze.h and defrem.h into command.c, to support
makingObjectNames and creating indices

* I removed the 'case CONSTR_PRIMARY' clause so that it properly fails and
says you can't add primary keys, rather than just doing nothing and
reporting nothing!!!

* I have modified the docs.

Algorithm
---------

* If name specified is null, search for a new valid constraint name.  I'm
not sure if I should "lock" my generated name somehow tho - should I open
the relation before doing this step?

* Open relation in access exclusive mode

* Check that the constraint does not already exist

* Define the new index

* Warn if they're doubling up on an existing index

Christopher Kings-Lynne

1 files changed, 11 insertions, 4 deletions

diff --git a/doc/src/sgml/ref/alter_table.sgml b/doc/src/sgml/ref/alter_table.sgml
index f5f22cb85dd..eb769468c66 100644
--- a/doc/src/sgml/ref/alter_table.sgml
+++ b/doc/src/sgml/ref/alter_table.sgml
@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.26 2001/09/03 12:57:49 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.27 2001/09/07 21:57:53 momjian Exp $
 Postgres documentation
 -->
 
@@ -211,9 +211,9 @@ ALTER TABLE <replaceable class="PARAMETER">table</replaceable>
    </para>
 
    <para>
-    In the current implementation, only FOREIGN KEY and CHECK constraints can
-    be added to a table.  To create a unique constraint, create 
-    a unique index (see <xref linkend="SQL-CREATEINDEX" 
+    In the current implementation, only UNIQUE, FOREIGN KEY and CHECK constraints can
+    be added to a table.  To create a primary constraint, create 
+    a unique, not null index (see <xref linkend="SQL-CREATEINDEX" 
     endterm="SQL-CREATEINDEX-title">).
    </para>
 
@@ -297,6 +297,13 @@ ALTER TABLE distributors DROP CONSTRAINT zipchk
 ALTER TABLE distributors ADD CONSTRAINT distfk FOREIGN KEY (address) REFERENCES addresses(address) MATCH FULL
    </programlisting>
   </para>
+
+  <para> 
+   To add a (multi-column) unique constraint to a table:
+   <programlisting>
+ALTER TABLE distributors ADD CONSTRAINT dist_id_zipcode_key UNIQUE (dist_id, zipcode)
+   </programlisting>
+  </para>
  </refsect1>
 
  <refsect1 id="R1-SQL-ALTERTABLE-3">