THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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There're Sessions and Operations in SqlGateway. SqlGateway will open a Session for each external connection FlinkConnection , and then do multiple Operations in one Session. When users create a FlinkSession by FlinkConnection by FlinkDriver with SqlGateway, it will open an exist or a new Session. Any time users want to issue SQL statements to the database, they require a FlinkStatement instance from FlinkConnection. Once users have a FlinkStatement , they can use issue a query. This will return a FlinkResultSet instance, which contains the entire result. Each operation such as the execution query(Flink job), fetching results in FlinkResultSet will be an Operation in the Session of SqlGateway .
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When an error occurs, Flink Jdbc Driver mainly throws the following exceptions
| SQLState Class | SQLState SubClass | Reason | Exception | Operations |
|---|---|---|---|---|
| 22 | 000 to 02H according to different errors | Description of data conversion error | SQLDataException | Get data error from ResultSet in methods getXXX |
| 0A | 000 | Specific feature is not supported | SQLFeatureNotSupportedException | All unimplemented methods will throw this exception |
| 58 | 004 | The exception or error message from Gateway | SQLNonTransientException | Gateway throws an exception or returns an error message when executing the query |
| 08 | 006 | The session is not exist in Gateway and client need to create new connection to it | SQLNonTransientConnectionException | Gateway is restarted and the client need to create new connection |
We can continue to subdivide and throw different exceptions according to the error information returned by the Gateway in Flink Jdbc Driver in the future
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