[jira] [Updated] (IMPALA-5929) Remove useless explicit casts to string

["Tim Armstrong (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/IMPALA-5929?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tim Armstrong updated IMPALA-5929:
----------------------------------
    Labels:   (was: newbie)

> Remove useless explicit casts to string
> ---------------------------------------
>
>                 Key: IMPALA-5929
>                 URL: https://issues.apache.org/jira/browse/IMPALA-5929
>             Project: IMPALA
>          Issue Type: Bug
>          Components: Frontend
>    Affects Versions: Impala 2.5.0, Impala 2.6.0, Impala 2.7.0, Impala 2.8.0, Impala 2.9.0, Impala 2.10.0
>            Reporter: Alexander Behm
>            Assignee: Bikramjeet Vig
>            Priority: Major
>
> Some BI tools like to generate expressions that look like this:
> {code}
> cast(numeric_col as string) = '123456'
> {code}
> Casting and comparing as string is expensive and we should convert such expressions to:
> {code}
> numeric_col = 123456
> {code}
> Such transformations may be applicable in other situations as well. We should be careful about transforming inequality predicates because the string and numeric comparison might not always be equivalent. For example, the following transformation would be wrong:
> {code}
> cast(numeric_col as string) = '0123456'
> {code}
> is *not* equivalent to 
> {code}
> numeric_col = 123456
> {code}



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