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https://issues.apache.org/jira/browse/TAJO-797?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13983986#comment-13983986
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Hyunsik Choi commented on TAJO-797:
-----------------------------------
Currently, Tajo partially supports implicit type conversion by using Datum's
arithmetic/comparable operation. This patch adds full implicit type conversion
feature. This feature inserts cast expressions to some operation whose operands
are compatible but need casting. Also, it is used in function invocation,
BETWEEN, and other kinds operations.
In addition, the patch fixes casting bugs. Currently, if there is some
arithmetic operation between FLOAT and LONG, both terms were casted to double
values and then were computed so far. But, it is different to the operation
based on IEEE 754. In such case, LONG should be casted float and then should be
computed.
Besides, the patch separates EvalNode into unary, binary, and others.
Currently, EvalNode has been always a binary expr and we have used some messy
hack to use EvalNode as unary, binary or others.
> Implicit type conversion support
> --------------------------------
>
> Key: TAJO-797
> URL: https://issues.apache.org/jira/browse/TAJO-797
> Project: Tajo
> Issue Type: Improvement
> Affects Versions: 0.8.0
> Reporter: Hyunsik Choi
> Assignee: Hyunsik Choi
> Fix For: 0.9.0
>
> Attachments: TAJO-797.patch
>
>
> Arithmetic and logical operations between different operands are usual in SQL
> queries. Function invocations with parameters which are different to the
> parameters of function definition are also usual. Implicit type conversion
> should occur in such cases.
> Currently, however, Tajo does not support implicit type conversion. We should
> implement this feature.
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