Kyle Buzsaki created PHOENIX-1206:
-------------------------------------
Summary: Decimal arithmetic with negative numbers rounds
incorrectly
Key: PHOENIX-1206
URL: https://issues.apache.org/jira/browse/PHOENIX-1206
Project: Phoenix
Issue Type: Bug
Reporter: Kyle Buzsaki
Our decimal type is supposed to support 38 digits of precision, but arithmetic
with negative numbers at any precision higher than 19 digits produces incorrect
results.
I have reproduced the error below. In the first two (incorrect) queries, the
right hand side is 1^-20 (19 zeros, then a 1). In the last two (correct)
queries, the right hand side is 1^-19 (18 zeros, then a 1).
Here's a reproduction in sqline:
{code}
0: jdbc:phoenix:localhost> create table demo (dec DECIMAL primary key);
No rows affected (0.264 seconds)
0: jdbc:phoenix:localhost> upsert into demo values(0.5);
1 row affected (0.006 seconds)
0: jdbc:phoenix:localhost> upsert into demo values(-0.5);
1 row affected (0.005 seconds)
0: jdbc:phoenix:localhost> select dec, dec + 0.00000000000000000001 from demo;
+------------+--------------------------------+
| DEC | (DEC + 0.00000000000000000001) |
+------------+--------------------------------+
| -0.5 | -0.50000000000000000057 |
| 0.5 | 0.50000000000000000001 |
+------------+--------------------------------+
2 rows selected (0.03 seconds)
0: jdbc:phoenix:localhost> select dec, dec - 0.00000000000000000001 from demo;
+------------+--------------------------------+
| DEC | (DEC - 0.00000000000000000001) |
+------------+--------------------------------+
| -0.5 | -0.49999999999999999999 |
| 0.5 | 0.49999999999999999999 |
+------------+--------------------------------+
2 rows selected (0.032 seconds)
0: jdbc:phoenix:localhost>
0: jdbc:phoenix:localhost> select dec, dec + 0.0000000000000000001 from demo;
+------------+-------------------------------+
| DEC | (DEC + 0.0000000000000000001) |
+------------+-------------------------------+
| -0.5 | -0.4999999999999999999 |
| 0.5 | 0.5000000000000000001 |
+------------+-------------------------------+
2 rows selected (0.032 seconds)
0: jdbc:phoenix:localhost> select dec, dec - 0.0000000000000000001 from demo;
+------------+-------------------------------+
| DEC | (DEC - 0.0000000000000000001) |
+------------+-------------------------------+
| -0.5 | -0.5000000000000000001 |
| 0.5 | 0.4999999999999999999 |
+------------+-------------------------------+
2 rows selected (0.029 seconds)
0: jdbc:phoenix:localhost>
{code}
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