[CASSANDRA-15232] Arithmetic operators over decimal truncate results

• Type: Improvement
• Status: Resolved
• Priority: Normal
• Resolution: Fixed
• Fix Version/s: 4.0-alpha1, 4.0
• Component/s: CQL/Semantics
• Labels: pull-request-available
• Change Category: Semantic
• Complexity: Low Hanging Fruit
• Platform: All

Source Control Link

d60e7988736ed4358595e9c781b110a5bbb5f812

Test and Documentation Plan

I did not run tests except OperationFctsTest

• Assignee: Liudmila Kornilova
• Reporter: Benedict Elliott Smith

Authors

Liudmila Kornilova

Reviewers

Benedict Elliott Smith

• Created: 17/Jul/19 07:15
• Updated: 15/May/20 08:01
• Resolved: 15/Aug/19 13:22

Description

The decimal operators hard-code a 128 bit precision for their computations. Probably a precision needs to be configured or decided somehow, but it’s not clear why 128bit was chosen. Particularly for multiplication and addition, it’s very unclear why we truncate, which is different to our behaviour for e.g. sum() aggregates. Probably for division we should also ensure that we do not reduce the precision of the two operands. A minimum of decimal128 seems reasonable, but a maximum does not.

Issue Links

• links to: GitHub Pull Request #334