Preliminary code review for domain CHECK constraints patch: add documentation,

make VALUE a non-reserved word again, use less invasive method of passing
ConstraintTestValue into transformExpr, fix problems with nested constraint
testing, do correct thing with NULL result from a constraint expression,
remove memory leak.  Domain checks still need much more work if we are going
to allow ALTER DOMAIN, however.

Author: tglsfdc

doc/src/sgml/ref/create_domain.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.8 2002/11/21 23:34:43 petere Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/create_domain.sgml,v 1.9 2002/12/12 20:35:07 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -30,7 +30,7 @@ CREATE DOMAIN <replaceable class="parameter">domainname</replaceable> [AS] <repl
 where <replaceable class="PARAMETER">constraint</replaceable> is:
 
 [ CONSTRAINT <replaceable class="PARAMETER">constraint_name</replaceable> ]
-{ NOT NULL | NULL }
+{ NOT NULL | NULL | CHECK (<replaceable class="PARAMETER">expression</replaceable>) }
   </synopsis>
 
   <refsect2 id="R2-SQL-CREATEDOMAIN-1">
@@ -128,6 +128,25 @@ where <replaceable class="PARAMETER">constraint</replaceable> is:
       </listitem>
      </varlistentry>
 
+   <varlistentry>
+    <term><literal>CHECK (<replaceable class="PARAMETER">expression</replaceable>)</literal></term>
+    <listitem>
+     <para>
+      <literal>CHECK</> clauses specify integrity constraints or tests
+      which values of the domain must satisfy.
+      Each constraint must be an expression
+      producing a Boolean result.  It should use the name <literal>VALUE</>
+      to refer to the value being tested.
+     </para>
+
+     <para>
+      Currently, <literal>CHECK</literal> expressions cannot contain
+      subselects nor refer to variables other than <literal>VALUE</>.
+     </para>
+
+    </listitem>
+   </varlistentry>
+
     </variablelist>
    </para>
   </refsect2>

doc/src/sgml/release.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.168 2002/11/26 22:04:03 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/release.sgml,v 1.169 2002/12/12 20:35:07 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[
+Domains now support CHECK constraints
 ]]></literallayout>
 
  </sect1>

src/backend/catalog/heap.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.236 2002/12/12 15:49:23 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/heap.c,v 1.237 2002/12/12 20:35:08 tgl Exp $
  *
  *
  * INTERFACE ROUTINES
@@ -1567,7 +1567,7 @@ AddRelationRawConstraints(Relation rel,
 		/*
 		 * Transform raw parsetree to executable expression.
 		 */
-		expr = transformExpr(pstate, cdef->raw_expr, NULL);
+		expr = transformExpr(pstate, cdef->raw_expr);
 
 		/*
 		 * Make sure it yields a boolean result.
@@ -1691,7 +1691,7 @@ cookDefault(ParseState *pstate,
 	/*
 	 * Transform raw parsetree to executable expression.
 	 */
-	expr = transformExpr(pstate, raw_default, NULL);
+	expr = transformExpr(pstate, raw_default);
 
 	/*
 	 * Make sure default expr does not refer to any vars.

src/backend/catalog/pg_constraint.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/catalog/pg_constraint.c,v 1.11 2002/12/06 05:00:10 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/catalog/pg_constraint.c,v 1.12 2002/12/12 20:35:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -439,18 +439,16 @@ RemoveConstraintById(Oid conId)
 	con = (Form_pg_constraint) GETSTRUCT(tup);
 
 	/*
-	 * If the constraint is for a relation, open and exclusive-lock
-	 * the relation it's for.
-	 *
-	 * If the constraint is for a domain, open and lock the pg_type entry
-	 * tye constraint is used on.
-	 *
-	 * XXX not clear what we should lock, if anything, for assert constraints.
+	 * Special processing depending on what the constraint is for.
 	 */
 	if (OidIsValid(con->conrelid))
 	{
 		Relation	rel;
 
+		/*
+		 * If the constraint is for a relation, open and exclusive-lock the
+		 * relation it's for.
+		 */
 		rel = heap_open(con->conrelid, AccessExclusiveLock);
 
 		/*
@@ -490,34 +488,14 @@ RemoveConstraintById(Oid conId)
 		/* Keep lock on constraint's rel until end of xact */
 		heap_close(rel, NoLock);
 	}
-	/* Lock the domain row in pg_type */
 	else if (OidIsValid(con->contypid))
 	{
-		Relation	typRel;
-		HeapTuple	typTup;
-		ScanKeyData typKey[1];
-		SysScanDesc typScan;
-		int			nkeys = 0;
-
-		typRel = heap_openr(TypeRelationName, RowExclusiveLock);
-
-		ScanKeyEntryInitialize(&typKey[nkeys++], 0x0,
-							   ObjectIdAttributeNumber, F_OIDEQ,
-							   ObjectIdGetDatum(con->contypid));
-
-		typScan = systable_beginscan(typRel, TypeOidIndex, true,
-									 SnapshotNow, nkeys, typKey);
-
-		typTup = systable_getnext(typScan);
-
-		if (!HeapTupleIsValid(typTup))
-			elog(ERROR, "RemoveConstraintById: Type %d does not exist",
-				 con->contypid);
-
-		systable_endscan(typScan);
-
-		/* Keep lock on domain type until end of xact */
-		heap_close(typRel, NoLock);
+		/*
+		 * XXX for now, do nothing special when dropping a domain constraint
+		 *
+		 * Probably there should be some form of locking on the domain type,
+		 * but we have no such concept at the moment.
+		 */
 	}
 	else
 	{

src/backend/commands/tablecmds.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.58 2002/12/12 15:49:24 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/commands/tablecmds.c,v 1.59 2002/12/12 20:35:12 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -2737,7 +2737,7 @@ AlterTableAddCheckConstraint(Relation rel, Constraint *constr)
 	/*
 	 * Convert the A_EXPR in raw_expr into an EXPR
 	 */
-	expr = transformExpr(pstate, constr->raw_expr, NULL);
+	expr = transformExpr(pstate, constr->raw_expr);
 
 	/*
 	 * Make sure it yields a boolean result.