[IMPALA-2788] Impala returns wrong result for function 'conv(bigint, from_base, to_base)'

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: Impala 2.3.0
• Fix Version/s: Impala 2.5.0, Impala 2.3.4
• Component/s: Backend
• Labels: correctness ramp-up
• Target Version: Impala 2.5.0, Impala 2.3.4
• Assignee: Mala Chikka Kempanna
• Reporter: Yibing Shi
• Created: 21/Dec/15 05:25
• Updated: 04/Jan/17 23:58
• Resolved: 09/Feb/16 00:45

Description

Impala returns wrong result for function 'conv'. Please see below command as example:

[10.17.80.14:21000] > select 2061013007, conv(2061013007, 16, 10), conv('2061013007', 16, 10) ;
Query: select 2061013007, conv(2061013007, 16, 10), conv('2061013007', 16, 10)
+------------+--------------------------+----------------------------+
| 2061013007 | conv(2061013007, 16, 10) | conv('2061013007', 16, 10) |
+------------+--------------------------+----------------------------+
| 2061013007 | 1627467783               | 139066421255               |
+------------+--------------------------+----------------------------+
Fetched 1 row(s) in 0.65s
[10.17.80.14:21000] > select 2061013007, conv(cast(2061013007 as bigint), 16, 10), conv('2061013007', 16, 10) ;
Query: select 2061013007, conv(cast(2061013007 as bigint), 16, 10), conv('2061013007', 16, 10)
+------------+------------------------------------------+----------------------------+
| 2061013007 | conv(cast(2061013007 as bigint), 16, 10) | conv('2061013007', 16, 10) |
+------------+------------------------------------------+----------------------------+
| 2061013007 | 1627467783 | 139066421255 |
+------------+------------------------------------------+----------------------------+
Fetched 1 row(s) in 0.03s
[10.17.80.14:21000] > select 2061013007, conv(cast(2061013007 as string), 16, 10), conv('2061013007', 16, 10) ;
Query: select 2061013007, conv(cast(2061013007 as string), 16, 10), conv('2061013007', 16, 10)
+------------+------------------------------------------+----------------------------+
| 2061013007 | conv(cast(2061013007 as string), 16, 10) | conv('2061013007', 16, 10) |
+------------+------------------------------------------+----------------------------+
| 2061013007 | 139066421255                             | 139066421255               |
+------------+------------------------------------------+----------------------------+
Fetched 1 row(s) in 0.02s
[10.17.80.14:21000] > select 2061013007, conv(cast(cast(2061013007 as decimal(20,0)) as bigint), 16, 10), conv('2061013007', 16, 10) ;
Query: select 2061013007, conv(cast(cast(2061013007 as decimal(20,0)) as bigint), 16, 10), conv('2061013007', 16, 10)
+------------+-----------------------------------------------------------------+----------------------------+
| 2061013007 | conv(cast(cast(2061013007 as decimal(20,0)) as bigint), 16, 10) | conv('2061013007', 16, 10) |
+------------+-----------------------------------------------------------------+----------------------------+
| 2061013007 | 1627467783                                                      | 139066421255               |
+------------+-----------------------------------------------------------------+----------------------------+
Fetched 1 row(s) in 0.03s

Function conv(bigint, from_base, to_base) doesn't return correct result, while conv(string, from_base, to_base) returns correct value.

This happens in CDH5.5 as well.

Workaround
Cast value to string and use conv(string, from_base, to_base) for conversion.