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https://issues.apache.org/jira/browse/FLINK-13503?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jark Wu updated FLINK-13503:
----------------------------
    Fix Version/s:     (was: 1.9.1)
                   1.9.2

> Add contract in `LookupableTableSource` to specify the behavior when 
> lookupKeys contains null
> ---------------------------------------------------------------------------------------------
>
>                 Key: FLINK-13503
>                 URL: https://issues.apache.org/jira/browse/FLINK-13503
>             Project: Flink
>          Issue Type: Task
>          Components: Connectors / JDBC, Table SQL / API
>    Affects Versions: 1.9.0, 1.10.0
>            Reporter: Jing Zhang
>            Assignee: Jing Zhang
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.10.0, 1.9.2
>
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> I think we should add contract in `LookupableTableSource` to specify expected 
> behavior when the lookupKeys contains null value.  
> For example, one input record of eval method is (null,1) which means to look 
> up data in (a,b) columns which key satisfy the requirement.  there are at 
> least three possibility here.
>   * to ignore null value, that is, in the above example, only looks `b = 1`
>   * to lookup `is value`, that is, in the above example, only looks `a is 
> null and b = 1`
>   * to return empty records, that is, in the above example, only looks `a = 
> null and b = 1`
> In fact, there are different behavior in current code. 
> For example, in Jdbc connector,
> The query template in `JdbcLookUpFunction` like:
> SELECT c, d, e, f from T where a = ? and b = ?
> If pass (null, 1) to `eval` method, it will generate the following query:
> SELECT c, d, e, f from T where a = null and b = 1
> Which always outputs empty records.
> BTW, Is this behavior reasonable?
> and the `InMemoryLookupableTableSource` behaviors like point 2 in the above 
> list.
> some private connector in Blink behaviors like point 1



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