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https://issues.apache.org/jira/browse/CALCITE-2321?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16483878#comment-16483878
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Hequn Cheng edited comment on CALCITE-2321 at 5/22/18 2:23 PM:
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Hi [~julianhyde], thanks for your reply. I test Oracle/SqlServer/Mysql and they
all return the value without blank-padded. Also, it seems that there is no way
to turn blank-padded on. I found some clear descriptions in mysql reference
manual: "If all types are character string (CHAR or VARCHAR), the result is
VARCHAR with maximum length determined by the longest character length of the
operands". Maybe we should make
{{shouldRaggedFixedLengthValueUnionBeVariable()}} configurable meanwhile return
true by default?
As for creating a type system, other system can create their own type system by
extending {{RelDataTypeSystemImpl}}, and this may not be a hard work. I tried
to set it via dialect, but find it is hard to make use of it in
{{SqlTypeFactoryImpl}} during sql to rel conversion. It seems that dialect is
used during rel to sql conversion.
Thanks, Hequn
was (Author: hequn8128):
Hi [~julianhyde], thanks for your reply. I test Oracle/SqlServer/Mysql and they
all return the value without blank-padded. Also, it seems that there is no way
to turn blank-padded on. Maybe we should make
{{shouldRaggedFixedLengthValueUnionBeVariable()}} configurable meanwhile return
true by default?
As for creating a type system, other system can create their own type system by
extending {{RelDataTypeSystemImpl}}, and this may not be a hard work. I tried
to set it via dialect, but find it is hard to make use of it in
{{SqlTypeFactoryImpl}} during sql to rel conversion. It seems that dialect is
used during rel to sql conversion.
Thanks, Hequn
> Support ragged fixed length value union be variable
> ---------------------------------------------------
>
> Key: CALCITE-2321
> URL: https://issues.apache.org/jira/browse/CALCITE-2321
> Project: Calcite
> Issue Type: New Feature
> Components: core
> Reporter: Hequn Cheng
> Assignee: Hequn Cheng
> Priority: Major
>
> The {{shouldRaggedFixedLengthValueUnionBeVariable()}} function in
> {{SqlTypeFactoryImpl}} always return false now. It is good to make it
> configurable since some system may need the function to return true to
> provide pragmatic behavior. For example, for the sql: case 1 when 1 then 'a'
> when 2 then 'bcd' end, we need the return value to be 'a' instead of 'a ' of
> CHAR(3).
> I see one option to solve this issue: Add {{boolean
> shouldRaggedFixedLengthValueUnionBeVariable()}} in {{RelDataTypeSystem}}, so
> external system can override to configure the value.
> Any suggestions are welcomed. Thanks a lot.
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