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https://issues.apache.org/jira/browse/CALCITE-3017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16827655#comment-16827655
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Hongze Zhang edited comment on CALCITE-3017 at 5/9/19 7:10 AM:
---------------------------------------------------------------
I am about to finish a patch resolving this (the work is at
https://github.com/zhztheplayer/calcite/tree/3017). The main approach is to
remove the implicit add of calls to {{JsonValueExpressionOperator}}, and use
Java method overload instead. This way a dejsonized NULL can be wrapped and
represent by a {{JsonValueContext}} object.
A downside of removing implicit calls is that users should implement the
implicit behavior by themselves. In a sense this is not quite a bad thing
because:
* It reduces complexity;
* "Implicit" behavior is reasonable to be considered in a lower level/layer.
Also, some minor refactors/changes done:
* Remove {{JsonApiCommonSyntaxOperator}}, the reason to do this is similar:
complexity reduced, and more flexibility gained;
* Move JSON processing functions out from {{SqlFunctions}}, create new one
named {{JsonFunctions}};
* Rex2Lix: Add explicit cast to Java type for null literal, to avoid error on
calling overloaded methods.
was (Author: zhztheplayer):
I am about to finished a patch resolving this (the work is at
https://github.com/zhztheplayer/calcite/tree/3017). The main approach is to
remove the implicit add of calls to {{JsonValueExpressionOperator}}, and use
Java method overload instead. This way a dejsonized NULL can be wrapped and
represent by a {{JsonValueContext}} object.
A downside of removing implicit calls is that users should implement the
implicit behavior by themselves. In a sense this is not quite a bad thing
because:
* It reduces complexity;
* "Implicit" behavior is reasonable to be considered in a lower level/layer.
Also, some minor refactors/changes done:
* Remove {{JsonApiCommonSyntaxOperator}}, the reason to do this is similar:
complexity reduced, and more flexibility gained;
* Move JSON processing functions out from {{SqlFunctions}}, create new one
named {{JsonFunctions}};
* Rex2Lix: Add explicit cast to Java type for null literal, to avoid error on
calling overloaded methods.
> Improve null handling of JsonValueExpressionOperator
> ----------------------------------------------------
>
> Key: CALCITE-3017
> URL: https://issues.apache.org/jira/browse/CALCITE-3017
> Project: Calcite
> Issue Type: Sub-task
> Reporter: Hongze Zhang
> Assignee: Hongze Zhang
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.20.0
>
> Time Spent: 0.5h
> Remaining Estimate: 0h
>
> In Calcite's implementation, {{JsonValueExpressionOperator}} currently
> returns a null value no matter the argument is JSON NULL value or SQL NULL
> value. But in MySQL, some JSON functions behave differently on different null
> inputs. For instance for a MySQL JSON function {{JSON_STORAGE_SIZE}}, if we
> execute:
> {code:sql}
> SELECT JSON_STORAGE_SIZE(null), JSON_STORAGE_SIZE('null')
> {code}
> The result should be:
> ||JSON_STORAGE_SIZE(null)||JSON_STORAGE_SIZE('null')||
> |null|2|
> We should improve the operator a bit to support different behaviors.
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