Do a pass of code review for the ALTER TABLE ADD INHERITS patch. Keep

the read lock we hold on the table's parent relation until commit.
Update equalfuncs.c for the new field in AlterTableCmd. Various
improvements to comments, variable names, and error reporting.

There is room for further improvement here, but this is at least
a step in the right direction.

src/backend/nodes/copyfuncs.c

@@ -15,7 +15,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.340 2006/07/02 02:23:20 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.341 2006/07/02 05:17:26 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1801,8 +1801,8 @@ _copyAlterTableCmd(AlterTableCmd *from)
 
 	COPY_SCALAR_FIELD(subtype);
 	COPY_STRING_FIELD(name);
-	COPY_NODE_FIELD(def);
 	COPY_NODE_FIELD(parent);
+	COPY_NODE_FIELD(def);
 	COPY_NODE_FIELD(transform);
 	COPY_SCALAR_FIELD(behavior);
 

src/backend/nodes/equalfuncs.c

@@ -18,7 +18,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.274 2006/07/02 02:23:20 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.275 2006/07/02 05:17:26 neilc Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -765,6 +765,7 @@ _equalAlterTableCmd(AlterTableCmd *a, AlterTableCmd *b)
 {
 	COMPARE_SCALAR_FIELD(subtype);
 	COMPARE_STRING_FIELD(name);
+	COMPARE_NODE_FIELD(parent);
 	COMPARE_NODE_FIELD(def);
 	COMPARE_NODE_FIELD(transform);
 	COMPARE_SCALAR_FIELD(behavior);

src/test/regress/expected/alter_table.out

@@ -342,9 +342,11 @@ alter table atacc3 inherit atacc2;
 alter table atacc3 inherit atacc2;
 ERROR:  inherited relation "atacc2" duplicated
 alter table atacc2 inherit atacc3;
-ERROR:  circular inheritance structure found, "atacc3" is already a child of "atacc2"
+ERROR:  circular inheritance structure found
+DETAIL:  "atacc3" is already a child of "atacc2".
 alter table atacc2 inherit atacc2;
-ERROR:  circular inheritance structure found, "atacc2" is already a child of "atacc2"
+ERROR:  circular inheritance structure found
+DETAIL:  "atacc2" is already a child of "atacc2".
 -- test that we really are a child now (should see 4 not 3 and cascade should go through)
 select test2 from atacc2;
  test2