Implement the new DECIMAL return type rules for divide and modulo
expressions, active when query option DECIMAL_V2=1. See the comment
in the code for more details. A couple of examples that show why new
return type rules for divide are desirable.
For modulo, the return types are actually equivalent, though the
rules are expressed differently to have consistency with how
precision fixups are handled for each version.
DECIMAL Version 1:
+-------------------------------------------------------+
| cast(1 as decimal(20,0)) / cast(3 as decimal(20,0)) |
+-----------------------------------------------------+
| 0 |
+-------------------------------------------------------+
DECIMAL Version 2:
+-------------------------------------------------------+
| cast(1 as decimal(20,0)) / cast(3 as decimal(20,0)) |
+-----------------------------------------------------+
| 0.333333333333333333 |
+-------------------------------------------------------+
DECIMAL Version 1:
+-------------------------------------------------------+
| cast(1 as decimal(6,0)) / cast(0.1 as decimal(38,38)) |
+-------------------------------------------------------+
| NULL |
+-------------------------------------------------------+
WARNINGS: UDF WARNING: Expression overflowed, returning NULL
DECIMAL Version 2:
+-------------------------------------------------------+
| cast(1 as decimal(6,0)) / cast(0.1 as decimal(38,38)) |
+-------------------------------------------------------+
| 10.000000 |
+-------------------------------------------------------+
Change-Id: I83e7f7787edfa4b4bddc25945090542a0e90881b
Reviewed-on: http://gerrit.cloudera.org:8080/5952
Reviewed-by: Dan Hecht <dhecht@cloudera.com>
Tested-by: Impala Public Jenkins
a53eeb2068