This patch implements ORACLE's COMMENT SQL command.

>From the ORACLE 7 SQL Language Reference Manual:
-----------------------------------------------------
COMMENT

Purpose:

To add a comment about a table, view, snapshot, or
column into the data dictionary.

Prerequisites:

The table, view, or snapshot must be in your own
schema
or you must have COMMENT ANY TABLE system privilege.

Syntax:

COMMENT ON [ TABLE table ] |
           [ COLUMN table.column] IS 'text'

You can effectively drop a comment from the database
by setting it to the empty string ''.
-----------------------------------------------------

Example:

COMMENT ON TABLE workorders IS
   'Maintains base records for workorder information';

COMMENT ON COLUMN workorders.hours IS
   'Number of hours the engineer worked on the task';

to drop a comment:

COMMENT ON COLUMN workorders.hours IS '';

The current patch will simply perform the insert into
pg_description, as per the TODO. And, of course, when
the table is dropped, any comments relating to it
or any of its attributes are also dropped. I haven't
looked at the ODBC source yet, but I do know from
an ODBC client standpoint that the standard does
support the notion of table and column comments.
Hopefully the ODBC driver is already fetching these
values from pg_description, but if not, it should be
trivial.

Hope this makes the grade,

Mike Mascari
(mascarim@yahoo.com)

5 files changed, 23 insertions, 5 deletions

diff --git a/src/include/catalog/heap.h b/src/include/catalog/heap.h
index faa708ff24..4720013160 100644
--- a/src/include/catalog/heap.h
+++ b/src/include/catalog/heap.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: heap.h,v 1.22 1999/10/03 23:55:35 tgl Exp $
+ * $Id: heap.h,v 1.23 1999/10/15 01:49:44 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -32,6 +32,9 @@ extern void heap_destroy_with_catalog(char *relname);
 extern void heap_truncate(char *relname);
 extern void heap_destroy(Relation rel);
 
+extern void CreateComments(Oid object, char *comments);
+extern void DeleteComments(Oid object);
+
 extern void AddRelationRawConstraints(Relation rel,
 									  List *rawColDefaults,
 									  List *rawConstraints);
diff --git a/src/include/catalog/pg_description.h b/src/include/catalog/pg_description.h
index d50da53d92..5db9204669 100644
--- a/src/include/catalog/pg_description.h
+++ b/src/include/catalog/pg_description.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: pg_description.h,v 1.8 1999/02/13 23:21:09 momjian Exp $
+ * $Id: pg_description.h,v 1.9 1999/10/15 01:49:44 momjian Exp $
  *
  * NOTES
  *		the genbki.sh script reads this file and generates .bki
@@ -65,3 +65,4 @@ typedef FormData_pg_description *Form_pg_description;
  */
 
 #endif	 /* PG_DESCRIPTION_H */
+
diff --git a/src/include/commands/creatinh.h b/src/include/commands/creatinh.h
index ffb111937a..11d5fdb7a0 100644
--- a/src/include/commands/creatinh.h
+++ b/src/include/commands/creatinh.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: creatinh.h,v 1.10 1999/09/23 17:03:16 momjian Exp $
+ * $Id: creatinh.h,v 1.11 1999/10/15 01:49:46 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -18,5 +18,6 @@
 extern void DefineRelation(CreateStmt *stmt, char relkind);
 extern void RemoveRelation(char *name);
 extern void TruncateRelation(char *name);
+extern void CommentRelation(char *name, char *attr, char *comment);
 
 #endif	 /* CREATINH_H */
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index 08705ea9f6..09f60466f4 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: nodes.h,v 1.54 1999/10/02 21:33:33 tgl Exp $
+ * $Id: nodes.h,v 1.55 1999/10/15 01:49:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -152,6 +152,7 @@ typedef enum NodeTag
 	T_DefineStmt,
 	T_DestroyStmt,
 	T_TruncateStmt,
+	T_CommentStmt,
 	T_ExtendStmt,
 	T_FetchStmt,
 	T_IndexStmt,
diff --git a/src/include/nodes/parsenodes.h b/src/include/nodes/parsenodes.h
index 1556bf3869..208b31d740 100644
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@@ -6,7 +6,7 @@
  *
  * Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parsenodes.h,v 1.84 1999/10/07 04:23:17 tgl Exp $
+ * $Id: parsenodes.h,v 1.85 1999/10/15 01:49:47 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -309,6 +309,18 @@ typedef struct TruncateStmt
         NodeTag         type;
         char	   *relName;            /* relation to be truncated */
 } TruncateStmt;
+
+/* ----------------------
+ *              Comment On Statement
+ * ----------------------
+ */
+typedef struct CommentStmt
+{
+  NodeTag         type;
+  char *relname;                       /* relation to create/drop comment */
+  char *attrname;                      /* attribute to comment on */
+  char *comment;                       /* the actual comment */
+} CommentStmt;
       
 /* ----------------------
  *		Extend Index Statement