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https://issues.apache.org/jira/browse/FLINK-30452?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17652157#comment-17652157
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Jing Zhang commented on FLINK-30452:
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Fix in master: 207975b416c324c634f0620e049669afea8cb8db
> Wrong argument type of null literal is used when call Hive's function
> ---------------------------------------------------------------------
>
> Key: FLINK-30452
> URL: https://issues.apache.org/jira/browse/FLINK-30452
> Project: Flink
> Issue Type: Sub-task
> Components: Connectors / Hive
> Reporter: luoyuxia
> Priority: Major
> Labels: pull-request-available
> Fix For: 1.17.0
>
>
> While calling Hive function, if the argument is void type, it will be
> [considered as string
> type|[https://github.com/apache/flink/blob/2e5cac1f31aa571276df20e24889994672692a89/flink-connectors/flink-connector-hive/src/main/java/org/apache/flink/table/functions/hive/conversion/HiveInspectors.java#L553]]
> , which may bring wrong type inference and thus may well cause other
> problems.
>
> For example,
> {code:java}
> timestamp(if(a = 0, null, a))
> {code}
> the argument for function `if` is `null` and `a`, null is void type, `a` is
> bigint type represents a timestamp, so the inferred return type should be
> bigint for the `if` function will ignore void type and just consider the
> other argument type. But we consider the void type as string type, the
> return type inferred will be string according to the `if` function inference
> logic.
> And then when we try to converted the value returned by `if(a = 0, null, a)`
> to timestamp, the unexpected behavior will happen:
> Since we infer the returned value of `if(a = 0, null, a)` as string, so
> `if(a = 0, null, a)` will return some thing like "1671058803926"，but
> cast ("1671058803926" as timestamp) will return null.
>
>
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