[HIVE-5800] Hive is inconsistent when handling strings in arithmetic operations

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.12.0
• Fix Version/s: 0.13.0
• Component/s: Types
• Assignee: Xuefu Zhang
• Reporter: Xuefu Zhang
• Created: 12/Nov/13 06:14
• Updated: 09/Dec/13 21:38
• Resolved: 09/Dec/13 21:38

Description

Currently Hive is inconsistent in dealing with strings involved in arithmetic operations. For instance:

hive> desc test;
OK
i                   	int                 	None                
b                   	boolean             	None                
d                   	double              	None                
s                   	string              	None                
dec                 	decimal(5,2)        	None                
Hive> explain select dec/s from test;
...
STAGE PLANS:
  Stage: Stage-1
    Map Reduce
      Alias -> Map Operator Tree:
        test 
          TableScan
            alias: test
            Select Operator
              expressions:
                    expr: (dec / s)
                    type: decimal(65,30)
              outputColumnNames: _col0
hive> explain select dec*s from test;
...
STAGE PLANS:
  Stage: Stage-1
    Map Reduce
      Alias -> Map Operator Tree:
        test 
          TableScan
            alias: test
            Select Operator
              expressions:
                    expr: (dec * s)
                    type: double

MySQL consistently treats string in arithmetic operations as double (not an exact numeric type) and derives the operator result type accordingly. Hive should also be consistent.