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

to resolve the unknown constants as type TEXT.

diff --git a/src/backend/parser/parse_coerce.c b/src/backend/parser/parse_coerce.c
index ef13d67cf1c63afb864abe2862ea0890a4afac87..f0d3427d17ef5fc99c267bad7febe1bdbb7250f9 100644 (file)
--- 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;
 }