[IMPALA-4915] Unbounded DECIMAL casts from floating point to decimal trigger undefined behavior

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 2.9.0
• Fix Version/s: Impala 2.9.0
• Component/s: Backend
• Assignee: Zach Amsden
• Reporter: Zachary
• Created: 11/Feb/17 03:05
• Updated: 14/Mar/17 18:36
• Resolved: 24/Feb/17 19:43

Description

Here's an example of using Impala as an ASCII art generator:

[localhost:21000] > select power(2, 1023) * 100;
Query: select power(2, 1023) * 100
Query submitted at: 2017-02-11 02:58:50 (Coordinator: http://impala-dev:25000)
Query progress can be monitored at: http://impala-dev:25000/query_plan?query_id=2346bde04782aabd:3466c05900000000
+----------------------+
| power(2, 1023) * 100 |
+----------------------+
| Infinity             |
+----------------------+
Fetched 1 row(s) in 0.01s
[localhost:21000] > select cast(power(2, 1023) * 100 AS decimal(10,10));
Query: select cast(power(2, 1023) * 100 AS decimal(10,10))
Query submitted at: 2017-02-11 02:59:20 (Coordinator: http://impala-dev:25000)
Query progress can be monitored at: http://impala-dev:25000/query_plan?query_id=de46ef0a381bc968:66f76aa600000000
+----------------------------------------------+
| cast(power(2, 1023) * 100 as decimal(10,10)) |
+----------------------------------------------+
| --.*(+,))+(0(                                |
+----------------------------------------------+
Fetched 1 row(s) in 0.01s
[localhost:21000] > set disable_codegen=1;
DISABLE_CODEGEN set to 1
[localhost:21000] > select cast(power(2, 1023) * 100 AS decimal(10,10));
Query: select cast(power(2, 1023) * 100 AS decimal(10,10))
Query submitted at: 2017-02-11 03:00:00 (Coordinator: http://impala-dev:25000)
Query progress can be monitored at: http://impala-dev:25000/query_plan?query_id=b64823307d95c477:5d8b586b00000000
+----------------------------------------------+
| cast(power(2, 1023) * 100 as decimal(10,10)) |
+----------------------------------------------+
| --.*(+,))+(0(                                |
+----------------------------------------------+
Fetched 1 row(s) in 0.01s
[localhost:21000] > set decimal_v2=1;
DECIMAL_V2 set to 1
[localhost:21000] > select cast(power(2, 1023) * 100 AS decimal(10,10));
Query: select cast(power(2, 1023) * 100 AS decimal(10,10))
Query submitted at: 2017-02-11 03:00:34 (Coordinator: http://impala-dev:25000)
Query progress can be monitored at: http://impala-dev:25000/query_plan?query_id=b24376cb151d7203:35baf9b300000000
+----------------------------------------------+
| cast(power(2, 1023) * 100 as decimal(10,10)) |
+----------------------------------------------+
| --.*(+,))+(0(                                |
+----------------------------------------------+
Fetched 1 row(s) in 0.01s