Arrange for CASE or UNION with only untyped literal constants as input

tglsfdc · tglsfdc · commit 372e598c44a9 · 2000-11-09T04:14:32.000Z
to resolve the unknown constants as type TEXT.
diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.47 2000/10/05 19:11:33 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.48 2000/11/09 04:14:32 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -374,6 +374,22 @@ select_common_type(List *typeids, const char *context)
 			}
 		}
 	}
+
+	/*
+	 * If all the inputs were UNKNOWN type --- ie, unknown-type literals ---
+	 * then resolve as type TEXT.  This situation comes up with constructs
+	 * like
+	 *			SELECT (CASE WHEN foo THEN 'bar' ELSE 'baz' END);
+	 *			SELECT 'foo' UNION SELECT 'bar';
+	 * It might seem desirable to leave the construct's output type as
+	 * UNKNOWN, but that really doesn't work, because we'd probably end up
+	 * needing a runtime coercion from UNKNOWN to something else, and we
+	 * usually won't have it.  We need to coerce the unknown literals while
+	 * they are still literals, so a decision has to be made now.
+	 */
+	if (ptype == UNKNOWNOID)
+		ptype = TEXTOID;
+
 	return ptype;
 }
 

Original file line number	Diff line number	Diff line change
`@@ -8,7 +8,7 @@`
`8`	`8`	`*`
`9`	`9`	`*`
`10`	`10`	`* IDENTIFICATION`
`11`		`- * $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.47 2000/10/05 19:11:33 tgl Exp $`
	`11`	`+ * $Header: /cvsroot/pgsql/src/backend/parser/parse_coerce.c,v 2.48 2000/11/09 04:14:32 tgl Exp $`
`12`	`12`	`*`
`13`	`13`	`*-------------------------------------------------------------------------`
`14`	`14`	`*/`
`@@ -374,6 +374,22 @@ select_common_type(List typeids, const char context)`
`374`	`374`	`}`
`375`	`375`	`}`
`376`	`376`	`}`
	`377`	`+`
	`378`	`+ /*`
	`379`	`+ * If all the inputs were UNKNOWN type --- ie, unknown-type literals ---`
	`380`	`+ * then resolve as type TEXT. This situation comes up with constructs`
	`381`	`+ * like`
	`382`	`+ * SELECT (CASE WHEN foo THEN 'bar' ELSE 'baz' END);`
	`383`	`+ * SELECT 'foo' UNION SELECT 'bar';`
	`384`	`+ * It might seem desirable to leave the construct's output type as`
	`385`	`+ * UNKNOWN, but that really doesn't work, because we'd probably end up`
	`386`	`+ * needing a runtime coercion from UNKNOWN to something else, and we`
	`387`	`+ * usually won't have it. We need to coerce the unknown literals while`
	`388`	`+ * they are still literals, so a decision has to be made now.`
	`389`	`+ */`
	`390`	`+ if (ptype == UNKNOWNOID)`
	`391`	`+ ptype = TEXTOID;`
	`392`	`+`
`377`	`393`	`return ptype;`
`378`	`394`	`}`
`379`	`395`