[IMPALA-2749] Impala returns NULL when decimal and double values are multiplied in a specific order

• Type: Bug
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Affects Version/s: Impala 2.2, Impala 2.3.0
• Fix Version/s: Impala 2.5.0, Impala 2.3.4
• Component/s: Frontend
• Labels: correctness ramp-up
• Target Version: Impala 2.5.0, Impala 2.3.4
• Assignee: Lars Volker
• Reporter: Yibing Shi
• Created: 08/Dec/15 01:07
• Updated: 22/Mar/18 22:58
• Resolved: 26/Jan/16 20:44

Description

For an expression like double_value * decimal_value * double_value and some specific values, impala returns NULL. But for the same value, expression double_value * double_value * decimal_value returns correct result. Please see below example for details:

[10.17.80.14:21000] > create table dec_test (dbl1 double, dec decimal(9,4), dbl2 double);
Query: create table dec_test (dbl1 double, dec decimal(9,4), dbl2 double)

Fetched 0 row(s) in 0.18s
[10.17.80.14:21000] > insert overwrite table dec_test values
                    > (0.0017,90,1.0113),
                    > (0.0342,90,1.0113),
                    > (0.0128,90,1.0113),
                    > (0.0163,90,1.0113);
Query: insert overwrite table dec_test values
(0.0017,90,1.0113),
(0.0342,90,1.0113),
(0.0128,90,1.0113),
(0.0163,90,1.0113)
Inserted 4 row(s) in 0.43s
[10.17.80.14:21000] > select dbl1 * dec * dbl2 from dec_test;
Query: select dbl1 * dec * dbl2 from dec_test
+------------------------------------------+
| dbl1 * dec * dbl2                        |
+------------------------------------------+
| 0.15472890000000002448000000000000000000 |
| NULL                                     |
| NULL                                     |
| NULL                                     |
+------------------------------------------+
WARNINGS: UDF WARNING: Expression overflowed, returning NULL
UDF WARNING: Expression overflowed, returning NULL
UDF WARNING: Expression overflowed, returning NULL

Fetched 4 row(s) in 0.50s
[10.17.80.14:21000] > select dbl1 * dbl2 * dec from dec_test;
Query: select dbl1 * dbl2 * dec from dec_test
+-------------------------+
| dbl1 * dbl2 * dec       |
+-------------------------+
| 0.154728900000000000000 |
| 3.112781400000000000000 |
| 1.165017600000000000000 |
| 1.483577100000000000000 |
+-------------------------+
Fetched 4 row(s) in 0.43s
[10.17.80.14:21000] >

Issue Links

• relates to: IMPALA-2681 Improve Decimal arithmetic performance by using a cheaper overflow check