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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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Jing Zhang updated FLINK-13503:
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Component/s: Table SQL / API
> 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
> Reporter: Jing Zhang
> Priority: Minor
>
> I think we should add contract in `LookupableTableSource` to specify expected
> behavior when the lookupKeys contains null value. Because there is ambiguity
> here, 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.
> * 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.
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