[IMPALA-1000] Casting all integer types to a legal Decimal is broken.

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: Impala 1.4
• Fix Version/s: Impala 1.4
• Labels: decimal
• Assignee: Nong Li
• Reporter: Ishaan Joshi
• Created: 12/May/14 22:11
• Updated: 20/Dec/15 00:05
• Resolved: 14/May/14 21:52

Description

Casting from an integer type to a legal Decimal type breaks down frequently.

I've used the following constraints to define what a legal decimal is:

smallint: 5 <= precision <= 38 && precision - scale >= 5
int: 10 <= precision <= 38 && precision - scale >= 10
bigint: 19 <= precision <= 38 && precision - scale >= 19

Example with smallint:

[localhost:21000] > select cast(-26659 as Decimal(27,18));
Query: select cast(-26659 as Decimal(27,18))
+--------------------------------+
| cast(-26659 as decimal(27,18)) |
+--------------------------------+
| -3.454813489697914880          |
+--------------------------------+
Returned 1 row(s) in 0.18s
[localhost:21000] > select cast(-32130 as Decimal(36,29));
Query: select cast(-32130 as Decimal(36,29))
+----------------------------------+
| cast(-32130 as decimal(36,29))   |
+----------------------------------+
| -0.00000000005300179331568369664 |
+----------------------------------+