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https://issues.apache.org/jira/browse/DRILL-8136?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17601846#comment-17601846
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ASF GitHub Bot commented on DRILL-8136:
---------------------------------------
jnturton commented on PR #2638:
URL: https://github.com/apache/drill/pull/2638#issuecomment-1240784918
> >
>
> That brings a tear to me eye!
A piece I haven't added is a cast function implementation going from BIT to
INT using the normal 0 = false, 1 = true correspondence to enable little
conveniences like taking the sum or average of a boolean. I enjoyed using
tricks like that in Impala IIRC. But the new casting logic here does provide
for this, all that's missing is the cast function itself:
```
Error: Missing function implementation: [castINT(BIT-OPTIONAL)]
``
> Overhaul implict type casting logic
> -----------------------------------
>
> Key: DRILL-8136
> URL: https://issues.apache.org/jira/browse/DRILL-8136
> Project: Apache Drill
> Issue Type: Improvement
> Reporter: Esther Buchwalter
> Assignee: James Turton
> Priority: Minor
>
> The existing implicit casting system is built on simplistic total ordering of
> data types[1] that yields oddities such as TINYINT being regarded as the
> closest numeric type to VARCHAR or DATE the closest type to FLOAT8. This, in
> turn, hurts the range of data types with which SQL functions can be used.
> E.g. `select sqrt('3.1415926')` works in many RDBMSes but not in Drill while,
> confusingly, `select '123' + 456` does work in Drill. In addition the
> limitations of the existing type precedence list mean that it has been
> supplmented with ad hoc secondary casting rules that go in the opposite
> direction.
> This Issue proposes a new, more flexible definition of casting distance based
> on a weighted directed graph built over the Drill data types.
> [1]
> [https://drill.apache.org/docs/supported-data-types/#implicit-casting-precedence-of-data-types]
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