Code and docs review for ALTER TABLE INHERIT/NO INHERIT patch.

doc/src/sgml/ref/alter_table.sgml

 <!--
-$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.90 2006/09/16 00:30:16 momjian Exp $
+$PostgreSQL: pgsql/doc/src/sgml/ref/alter_table.sgml,v 1.91 2006/10/13 21:43:18 tgl Exp $
 PostgreSQL documentation
 -->
 
@@ -294,28 +294,22 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
     <term><literal>INHERIT <replaceable class="PARAMETER">parent_table</replaceable></literal></term>
     <listitem>
      <para>
-      This form adds a new parent table to the table. This won't add new
-      columns to the child table, instead all columns of the parent table must
-      already exist in the child table. They must have matching data types,
+      This form adds the target table as a new child of the specified parent
+      table.  Subsequently, queries against the parent will include records
+      of the target table.  To be added as a child, the target table must
+      already contain all the same columns as the parent (it could have
+      additional columns, too).  The columns must have matching data types,
       and if they have <literal>NOT NULL</literal> constraints in the parent
       then they must also have <literal>NOT NULL</literal> constraints in the
       child.
      </para>
 
      <para>
-      There must also be matching table constraints for all
-      <literal>CHECK</literal> table constraints of the parent. Currently
+      There must also be matching child-table constraints for all
+      <literal>CHECK</literal> constraints of the parent. Currently
       <literal>UNIQUE</literal>, <literal>PRIMARY KEY</literal>, and
-      <literal>FOREIGN KEY</literal> constraints are ignored however this may
-      change in the future.
-     </para>
-
-     <para>
-      The easiest way to create a suitable table is to create a table using
-      <literal>INHERITS</literal> and then remove it via <literal>NO
-      INHERIT</literal>. Alternatively create a table using
-      <literal>LIKE</literal> however note that <literal>LIKE</literal> does
-      not create the necessary constraints.
+      <literal>FOREIGN KEY</literal> constraints are not considered, but
+      this may change in the future.
      </para>
     </listitem>
    </varlistentry>
@@ -324,7 +318,8 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
     <term><literal>NO INHERIT <replaceable class="PARAMETER">parent_table</replaceable></literal></term>
     <listitem>
      <para>
-      This form removes a parent table from the list of parents of the table.
+      This form removes the target table from the list of children of the
+      specified parent table.
       Queries against the parent table will no longer include records drawn
       from the target table.
      </para>
@@ -392,6 +387,8 @@ where <replaceable class="PARAMETER">action</replaceable> is one of:
    You must own the table to use <command>ALTER TABLE</>.
    To change the schema of a table, you must also have
    <literal>CREATE</literal> privilege on the new schema.
+   To add the table as a new child of a parent table, you must own the
+   parent table as well.
    To alter the owner, you must also be a direct or indirect member of the new
    owning role, and that role must have <literal>CREATE</literal> privilege on
    the table's schema.  (These restrictions enforce that altering the owner

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 1.351 2006/10/04 00:29:53 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/copyfuncs.c,v 1.352 2006/10/13 21:43:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1821,7 +1821,6 @@ _copyAlterTableCmd(AlterTableCmd *from)
 
 	COPY_SCALAR_FIELD(subtype);
 	COPY_STRING_FIELD(name);
-	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 1.285 2006/10/04 00:29:53 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/nodes/equalfuncs.c,v 1.286 2006/10/13 21:43:18 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -768,7 +768,6 @@ _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/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.566 2006/09/28 20:51:42 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/gram.y,v 2.567 2006/10/13 21:43:19 tgl Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -1506,20 +1506,20 @@ alter_table_cmd:
 					n->subtype = AT_DisableTrigUser;
 					$$ = (Node *)n;
 				}
-			/* ALTER TABLE <name> ALTER INHERITS ADD <parent> */
+			/* ALTER TABLE <name> INHERIT <parent> */
 			| INHERIT qualified_name
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
-					n->subtype = AT_AddInherits;
-					n->parent = $2;
+					n->subtype = AT_AddInherit;
+					n->def = (Node *) $2;
 					$$ = (Node *)n;
 				}
-			/* ALTER TABLE <name> alter INHERITS DROP <parent> */
+			/* ALTER TABLE <name> NO INHERIT <parent> */
 			| NO INHERIT qualified_name
 				{
 					AlterTableCmd *n = makeNode(AlterTableCmd);
-					n->subtype = AT_DropInherits;
-					n->parent = $3;
+					n->subtype = AT_DropInherit;
+					n->def = (Node *) $3;
 					$$ = (Node *)n;
 				}
 			| alter_rel_cmd

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.332 2006/10/11 16:42:59 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/nodes/parsenodes.h,v 1.333 2006/10/13 21:43:19 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -905,8 +905,8 @@ typedef enum AlterTableType
 	AT_DisableTrigAll,			/* DISABLE TRIGGER ALL */
 	AT_EnableTrigUser,			/* ENABLE TRIGGER USER */
 	AT_DisableTrigUser,			/* DISABLE TRIGGER USER */
-	AT_AddInherits,				/* ADD INHERITS parent */
-	AT_DropInherits				/* DROP INHERITS parent */
+	AT_AddInherit,				/* INHERIT parent */
+	AT_DropInherit				/* NO INHERIT parent */
 } AlterTableType;
 
 typedef struct AlterTableCmd	/* one subcommand of an ALTER TABLE */
@@ -915,9 +915,8 @@ typedef struct AlterTableCmd	/* one subcommand of an ALTER TABLE */
 	AlterTableType subtype;		/* Type of table alteration to apply */
 	char	   *name;			/* column, constraint, or trigger to act on,
 								 * or new owner or tablespace */
-	RangeVar   *parent;			/* Parent table for add/drop inherits */
 	Node	   *def;			/* definition of new column, column type,
-								 * index, or constraint */
+								 * index, constraint, or parent table */
 	Node	   *transform;		/* transformation expr for ALTER TYPE */
 	DropBehavior behavior;		/* RESTRICT or CASCADE for DROP cases */
 } AlterTableCmd;

src/test/regress/expected/alter_table.out

@@ -324,7 +324,7 @@ select test2 from atacc2;
 -- fail due to missing constraint
 alter table atacc2 add constraint foo check (test2>0);
 alter table atacc3 inherit atacc2;
-ERROR:  child table missing constraint matching parent table constraint "foo"
+ERROR:  child table is missing constraint "foo"
 -- fail due to missing column
 alter table atacc3 rename test2 to testx;
 alter table atacc3 inherit atacc2;
@@ -342,10 +342,10 @@ 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
+ERROR:  circular inheritance not allowed
 DETAIL:  "atacc3" is already a child of "atacc2".
 alter table atacc2 inherit atacc2;
-ERROR:  circular inheritance structure found
+ERROR:  circular inheritance not allowed
 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;