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https://issues.apache.org/jira/browse/FLINK-20986?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17322865#comment-17322865
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Flink Jira Bot commented on FLINK-20986:
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This issue is assigned but has not received an update in 7 days so it has been
labeled "stale-assigned". If you are still working on the issue, please give an
update and remove the label. If you are no longer working on the issue, please
unassign so someone else may work on it. In 7 days the issue will be
automatically unassigned.
> GenericTypeInfo equality issue
> ------------------------------
>
> Key: FLINK-20986
> URL: https://issues.apache.org/jira/browse/FLINK-20986
> Project: Flink
> Issue Type: Sub-task
> Components: Table SQL / Planner
> Affects Versions: 1.12.0
> Reporter: Tianshi Zhu
> Assignee: Timo Walther
> Priority: Major
> Labels: pull-request-available, stale-assigned
>
> When trying to use Flink REST api to run a job that uses Flink table api with
> blink planner, we encountered an issue about `Incompatible types of
> expression and result type.` from
> org.apache.flink.table.planner.codegen.ExprCodeGenerator$$anonfun$generateResultExpression$1.apply(ExprCodeGenerator.scala:311).
> This issue only happens after the first request has been handled
> successfully.
>
> After digging, we found that there are two static caches used inside calcite's
> RelDataTypeFactoryImpl (
> https://github.com/apache/calcite/blob/d9a81b88ad561e7e4cedae93e805e0d7a53a7f1a/core/src/main/java/org/apache/calcite/rel/type/RelDataTypeFactoryImpl.java#L352-L376
> ), which will remember the types they have seen. The `canonize` method is
> called from FlinkTypeFactory
> https://github.com/apache/flink/blob/89f9dcd70dc3a1433055e17775b2b2a2c796ca94/flink-table/flink-table-planner-blink/src/main/scala/org/apache/flink/table/planner/calcite/FlinkTypeFactory.scala#L292
>
> This causes problem for us because in our experience, we have seen
> GenericTypeInfo<T> containing different Class<T> instances in two different
> REST requests, and they do not equal, because
> [https://github.com/apache/flink/blob/89f9dcd70dc3a1433055e17775b2b2a2c796ca94/flink-core/src/main/java/org/apache/flink/api/java/typeutils/GenericTypeInfo.java#L124]
> is using object equality. After `canonize`, the GenericTypeInfo for other
> REST requests would be changed to the GenericTypeInfo used for the first REST
> request, which is cached in RelDataTypeFactoryImpl. And this leads to the
> incompatible type error mentioned above.
>
> I want to propose using class name for equality comparison inside
> GenericTypeInfo, and change hashCode method accordingly.
>
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