Back out patch added during 8.2.X development:

bmomjian · bmomjian · commit 94cf48d72b2d · 2006-09-10T22:54:47.000Z
Allow to_char() "D" format specifiers for interval/time.

It doesn't work, and I doubt it is useful enough to fix ("D" = day of
week).
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
@@ -1,7 +1,7 @@
 /* -----------------------------------------------------------------------
  * formatting.c
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.111 2006/09/03 01:22:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.112 2006/09/10 22:54:47 momjian Exp $
  *
  *
  *	 Portions Copyright (c) 1999-2006, PostgreSQL Global Development Group
@@ -2367,6 +2367,7 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,
 			}
 			break;
 		case DCH_D:
+			INVALID_FOR_INTERVAL;
 			if (is_to_char)
 			{
 				sprintf(inout, "%d", tm->tm_wday + 1);

Original file line number	Diff line number	Diff line change
`@@ -1,7 +1,7 @@`
`1`	`1`	`/* -----------------------------------------------------------------------`
`2`	`2`	`* formatting.c`
`3`	`3`	`*`
`4`		`- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.111 2006/09/03 01:22:56 momjian Exp $`
	`4`	`+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.112 2006/09/10 22:54:47 momjian Exp $`
`5`	`5`	`*`
`6`	`6`	`*`
`7`	`7`	`* Portions Copyright (c) 1999-2006, PostgreSQL Global Development Group`
`@@ -2367,6 +2367,7 @@ dch_date(int arg, char *inout, int suf, bool is_to_char, bool is_interval,`
`2367`	`2367`	`}`
`2368`	`2368`	`break;`
`2369`	`2369`	`case DCH_D:`
	`2370`	`+ INVALID_FOR_INTERVAL;`
`2370`	`2371`	`if (is_to_char)`
`2371`	`2372`	`{`
`2372`	`2373`	`sprintf(inout, "%d", tm->tm_wday + 1);`