Patch of 2004-03-30 corrected date_part(timestamp) for extracting

the year from a BC date, but failed to make the same fix in
date_part(timestamptz).

src/backend/utils/adt/timestamp.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.114 2004/11/01 22:00:30 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/adt/timestamp.c,v 1.115 2004/11/20 22:12:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -3534,7 +3534,11 @@ timestamptz_part(PG_FUNCTION_ARGS)
 				break;
 
 			case DTK_YEAR:
-				result = tm->tm_year;
+				if (tm->tm_year > 0)
+					result = tm->tm_year;
+				else
+					/* there is no year 0, just 1 BC and 1 AD */
+					result = tm->tm_year - 1;
 				break;
 
 			case DTK_DECADE: