The attached patch (against HEAD) implements

  COPY x (a,d,c,b) from stdin;
  COPY x (a,c) to stdout;

as well as the corresponding changes to pg_dump to use the new
functionality.  This functionality is not available when using
the BINARY option.  If a column is not specified in the COPY FROM
statement, its default values will be used.

In addition to this functionality, I tweaked a couple of the
error messages emitted by the new COPY <options> checks.

Brent Verner

doc/src/sgml/ref/copy.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/ref/copy.sgml,v 1.32 2002/06/20 16:00:43 momjian Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/ref/copy.sgml,v 1.33 2002/07/18 04:43:50 momjian Exp $
 PostgreSQL documentation
 -->
 
@@ -21,7 +21,8 @@ PostgreSQL documentation
    <date>1999-12-11</date>
   </refsynopsisdivinfo>
   <synopsis>
-COPY <replaceable class="parameter">table</replaceable>
+COPY <replaceable class="parameter">table</replaceable> 
+    [ ( <replaceable class="parameter">column</replaceable> [, ...] ) ]
     FROM { '<replaceable class="parameter">filename</replaceable>' | <filename>stdin</filename> }
     [ [ WITH ] 
           [ BINARY ] 
@@ -29,6 +30,7 @@ COPY <replaceable class="parameter">table</replaceable>
           [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter</replaceable>' ]
           [ NULL [ AS ] '<replaceable class="parameter">null string</replaceable>' ] ]
 COPY <replaceable class="parameter">table</replaceable>
+    [ ( <replaceable class="parameter">column</replaceable> [, ...] ) ]
     TO { '<replaceable class="parameter">filename</replaceable>' | <filename>stdout</filename> }
     [ [ WITH ] 
           [ BINARY ]
@@ -55,6 +57,16 @@ COPY <replaceable class="parameter">table</replaceable>
        </para>
       </listitem>
      </varlistentry>
+     
+		 <varlistentry>
+      <term><replaceable class="parameter">column list</replaceable></term>
+      <listitem>
+       <para>
+	An optional list of columns to be copied.  If no column list is
+	specified, all columns will be used.
+       </para>
+      </listitem>
+     </varlistentry>
 
      <varlistentry>
       <term><replaceable class="parameter">filename</replaceable></term>
@@ -187,6 +199,14 @@ ERROR: <replaceable>reason</replaceable>
    whatever is in the table already).
   </para>
 
+	<para>
+   When using the optional column list syntax, <command>COPY TO</command> 
+	 and <command>COPY FROM</command> will only copy the specified
+	 columns' values to/from the table. If a column in the table
+	 is not in the column list, <command>COPY FROM</command> will insert 
+	 default values for that column if a default value is defined.
+  </para>
+
   <para>
    <command>COPY</command> with a file name instructs the
    <productname>PostgreSQL</productname> backend to directly read from

src/backend/parser/gram.y

@@ -11,7 +11,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.343 2002/07/18 04:41:45 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/gram.y,v 2.344 2002/07/18 04:43:50 momjian Exp $
  *
  * HISTORY
  *	  AUTHOR			DATE			MAJOR EVENT
@@ -1262,31 +1262,32 @@ opt_id: 	ColId									{ $$ = $1; }
 /*****************************************************************************
  *
  *		QUERY :
- *				COPY <relname> FROM/TO [WITH options]
+ *				COPY <relname> ['(' columnList ')'] FROM/TO [WITH options]
  *
  *				BINARY, OIDS, and DELIMITERS kept in old locations
  *				for backward compatibility.  2002-06-18
  *
  *****************************************************************************/
 
-CopyStmt:	COPY opt_binary qualified_name opt_oids copy_from
-			copy_file_name copy_delimiter opt_with copy_opt_list
+CopyStmt:	COPY opt_binary qualified_name opt_column_list opt_oids 
+			copy_from copy_file_name copy_delimiter opt_with copy_opt_list
 				{
 					CopyStmt *n = makeNode(CopyStmt);
 					n->relation = $3;
-					n->is_from = $5;
-					n->filename = $6;
+					n->attlist = $4;
+					n->is_from = $6;
+					n->filename = $7;
 
 					n->options = NIL;
 					/* Concatenate user-supplied flags */
 					if ($2)
 						n->options = lappend(n->options, $2);
-					if ($4)
-						n->options = lappend(n->options, $4);
-					if ($7)
-						n->options = lappend(n->options, $7);
-					if ($9)
-						n->options = nconc(n->options, $9);
+					if ($5)
+						n->options = lappend(n->options, $5);
+					if ($8)
+						n->options = lappend(n->options, $8);
+					if ($10)
+						n->options = nconc(n->options, $10);
 					$$ = (Node *)n;
 				}
 		;

src/backend/rewrite/rewriteHandler.c

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1994, Regents of the University of California
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.103 2002/06/20 20:29:34 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/rewrite/rewriteHandler.c,v 1.104 2002/07/18 04:43:50 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -43,7 +43,6 @@ static List *adjustJoinTreeList(Query *parsetree, bool removert, int rt_index);
 static void rewriteTargetList(Query *parsetree, Relation target_relation);
 static TargetEntry *process_matched_tle(TargetEntry *src_tle,
 										TargetEntry *prior_tle);
-static Node *build_column_default(Relation rel, int attrno);
 static void markQueryForUpdate(Query *qry, bool skipOldNew);
 static List *matchLocks(CmdType event, RuleLock *rulelocks,
 		   int varno, Query *parsetree);
@@ -411,7 +410,7 @@ process_matched_tle(TargetEntry *src_tle,
  *
  * If there is no default, return a NULL instead.
  */
-static Node *
+Node *
 build_column_default(Relation rel, int attrno)
 {
 	TupleDesc	rd_att = rel->rd_att;

src/bin/pg_dump/pg_dump.c

@@ -22,7 +22,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/bin/pg_dump/pg_dump.c,v 1.271 2002/07/12 18:43:18 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/bin/pg_dump/pg_dump.c,v 1.272 2002/07/18 04:43:50 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -133,6 +133,7 @@ static char *GetPrivileges(Archive *AH, const char *s, const char *type);
 static int	dumpBlobs(Archive *AH, char *, void *);
 static int	dumpDatabase(Archive *AH);
 static const char *getAttrName(int attrnum, TableInfo *tblInfo);
+static const char* fmtCopyColumnList(const TableInfo* ti);
 
 extern char *optarg;
 extern int	optind,
@@ -842,6 +843,7 @@ dumpClasses_nodumpData(Archive *fout, char *oid, void *dctxv)
 	int			ret;
 	bool		copydone;
 	char		copybuf[COPYBUFSIZ];
+  const char*   column_list;
 
 	if (g_verbose)
 		write_msg(NULL, "dumping out the contents of table %s\n", classname);
@@ -854,17 +856,19 @@ dumpClasses_nodumpData(Archive *fout, char *oid, void *dctxv)
 	 */
 	selectSourceSchema(tbinfo->relnamespace->nspname);
 
+	column_list = fmtCopyColumnList(tbinfo);
+
 	if (oids && hasoids)
 	{
-		appendPQExpBuffer(q, "COPY %s WITH OIDS TO stdout;",
+		appendPQExpBuffer(q, "COPY %s %s WITH OIDS TO stdout;",
 						  fmtQualifiedId(tbinfo->relnamespace->nspname,
-										 classname));
+										 classname),column_list);
 	}
 	else
 	{
-		appendPQExpBuffer(q, "COPY %s TO stdout;",
+		appendPQExpBuffer(q, "COPY %s %s TO stdout;",
 						  fmtQualifiedId(tbinfo->relnamespace->nspname,
-										 classname));
+										 classname), column_list);
 	}
 	res = PQexec(g_conn, q->data);
 	if (!res ||
@@ -1189,8 +1193,9 @@ dumpClasses(const TableInfo *tblinfo, const int numTables, Archive *fout,
 			{
 				/* Dump/restore using COPY */
 				dumpFn = dumpClasses_nodumpData;
-				sprintf(copyBuf, "COPY %s %sFROM stdin;\n",
-						fmtId(tblinfo[i].relname, force_quotes),
+				sprintf(copyBuf, "COPY %s %s %sFROM stdin;\n",
+						fmtQualifiedId(tblinfo[i].relnamespace->nspname,tblinfo[i].relname),
+						fmtCopyColumnList(&(tblinfo[i])),
 						(oids && tblinfo[i].hasoids) ? "WITH OIDS " : "");
 				copyStmt = copyBuf;
 			}
@@ -5860,3 +5865,38 @@ fmtQualifiedId(const char *schema, const char *id)
 
 	return id_return->data;
 }
+
+/*
+ * return a column list clause for the qualified relname.
+ * returns an empty string if the remote server is older than
+ * 7.3.
+ */
+static const char*
+fmtCopyColumnList(const TableInfo* ti)
+{
+	static PQExpBuffer q = NULL;
+	int			numatts = ti->numatts;
+	char**  attnames = ti->attnames;
+	int i;
+
+	if (g_fout->remoteVersion < 70300 )
+		return "";
+
+	if (q)				/* first time through? */
+		resetPQExpBuffer(q);
+	else
+		q = createPQExpBuffer();
+
+	resetPQExpBuffer(q);
+	
+	appendPQExpBuffer(q,"(");
+	for (i = 0; i < numatts; i++)
+	{
+		if( i > 0 )
+			appendPQExpBuffer(q,",");
+		appendPQExpBuffer(q, fmtId(attnames[i], force_quotes));
+	}
+	appendPQExpBuffer(q, ")");
+	return q->data;
+}
+

src/include/nodes/parsenodes.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: parsenodes.h,v 1.189 2002/07/18 04:42:29 momjian Exp $
+ * $Id: parsenodes.h,v 1.190 2002/07/18 04:43:51 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -884,6 +884,7 @@ typedef struct CopyStmt
 {
 	NodeTag		type;
 	RangeVar   *relation;		/* the relation to copy */
+	List *attlist;
 	bool		is_from;		/* TO or FROM */
 	char	   *filename;		/* if NULL, use stdin/stdout */
 	List	   *options;		/* List of DefElem nodes */

src/include/rewrite/rewriteHandler.h

@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2002, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $Id: rewriteHandler.h,v 1.19 2002/06/20 20:29:52 momjian Exp $
+ * $Id: rewriteHandler.h,v 1.20 2002/07/18 04:43:51 momjian Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,7 +16,7 @@
 
 #include "nodes/parsenodes.h"
 
-
 extern List *QueryRewrite(Query *parsetree);
+extern Node *build_column_default(Relation rel, int attrno);
 
 #endif   /* REWRITEHANDLER_H */

src/test/regress/parallel_schedule

@@ -74,4 +74,4 @@ test: select_views alter_table portals_p2 rules foreign_key
 # The sixth group of parallel test
 # ----------
 # "plpgsql" cannot run concurrently with "rules"
-test: limit plpgsql temp domain rangefuncs
+test: limit plpgsql temp domain rangefuncs copy2

src/test/regress/serial_schedule

-# $Header: /cvsroot/pgsql/src/test/regress/serial_schedule,v 1.10 2002/06/20 17:09:42 momjian Exp $
+# $Header: /cvsroot/pgsql/src/test/regress/serial_schedule,v 1.11 2002/07/18 04:43:51 momjian Exp $
 # This should probably be in an order similar to parallel_schedule.
 test: boolean
 test: char
@@ -80,6 +80,7 @@ test: rules
 test: foreign_key
 test: limit
 test: plpgsql
+test: copy2
 test: temp
 test: domain
 test: rangefuncs