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https://issues.apache.org/jira/browse/FLINK-20386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17247790#comment-17247790
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jiawen xiao commented on FLINK-20386:
-------------------------------------
[~jark]
_share my method here which is a large_ _amount_ __ _of_ __ _work:_
_we can get jdbc/mysql scheme by DatabaseMetaData and map to flink datatype
at same time which can be validated with source table schema or sink table
schema. it will throw ValidationException("Field types of mysql-schema result
and registered TableSource do not match") ._
_This idea comes from TableSinkUtils.validateSchemaAndApplyImplicitCast
(release 1.11)_
_What do you think，jark_
> ClassCastException when lookup join a JDBC table on INT UNSIGNED column
> -----------------------------------------------------------------------
>
> Key: FLINK-20386
> URL: https://issues.apache.org/jira/browse/FLINK-20386
> Project: Flink
> Issue Type: Bug
> Components: Connectors / JDBC, Table SQL / Ecosystem
> Affects Versions: 1.12.0, 1.11.2
> Reporter: Jark Wu
> Assignee: jiawen xiao
> Priority: Major
> Time Spent: 336h
> Remaining Estimate: 0h
>
> The primary key of the MySQL is an INT UNSIGNED column, but declared INT in
> Flink.
> I know the
> [docs|https://ci.apache.org/projects/flink/flink-docs-release-1.11/dev/table/connectors/jdbc.html#data-type-mapping]
> say it should be decalred BIGINT in Flink, however, would be better not fail
> the job.
> At least, the exception is hard to understand for users. We can also check
> the schema before start the job.
> {code}
> java.lang.ClassCastException: java.lang.Long cannot be cast to
> java.lang.Integer
> at
> org.apache.flink.table.data.GenericRowData.getInt(GenericRowData.java:149)
> ~[flink-table-blink_2.11-1.11-vvr-2.1.1-SNAPSHOT.jar:1.11-vvr-2.1.1-SNAPSHOT]
> at JoinTableFuncCollector$6460.collect(Unknown Source) ~[?:?]
> at
> org.apache.flink.table.functions.TableFunction.collect(TableFunction.java:203)
> ~[flink-table-blink_2.11-1.11-vvr-2.1.1-SNAPSHOT.jar:1.11-vvr-2.1.1-SNAPSHOT]
> at
> org.apache.flink.connector.jdbc.table.JdbcRowDataLookupFunction.eval(JdbcRowDataLookupFunction.java:162)
> ~[?:?]
> {code}
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