[
https://issues.apache.org/jira/browse/PHOENIX-1075?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14058067#comment-14058067
]
Kyle Buzsaki commented on PHOENIX-1075:
---------------------------------------
I ran the full suite of integration tests on the pre-addition/subtraction
changes version of the code and everything passed. As I'm fairly certain that
the symptoms won't affect addition and subtraction, I think it would be better
to just leave that part of the grammar as is and only use the changes to the
multiplication and division expression.
> Mathematical order of operations are improperly evaluated.
> ----------------------------------------------------------
>
> Key: PHOENIX-1075
> URL: https://issues.apache.org/jira/browse/PHOENIX-1075
> Project: Phoenix
> Issue Type: Bug
> Reporter: Kyle Buzsaki
> Attachments: PHOENIX-1075.patch
>
>
> The root of the issue is that, as things are now, multiplication and division
> don't actually have the same precedence in the grammar. Division is always
> grouped more tightly than multiplication and is evaluated first. Most of the
> time, this doesn't matter, but combined with the truncating integer division
> used by LongDivideExpression it produces some unexpected and probably wrong
> behavior. Below is an example:
> Expression: 6 * 4 / 3
> Evaluating left to right, this should reduce as follows:
> 6 * 4 / 3
> 24 / 3
> 8
> As phoenix is now, division has a higher precedence than multiplication.
> Therefore, the resulting expression tree looks like this:
> !http://i.imgur.com/2Zzsfpy.png!
> Because integer division in truncating, when the division evaluates the
> expression tree looks like this:
> !http://i.imgur.com/3cLGD0e.png!
> Which then evaluates to 6.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
