'Unknown datatype: JSON.' in ADO.NET Provider for Presto

Live Connectivity CData Drivers
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1

I’m getting the following exception when trying to run the following code.  Does the driver support the Trino JSON type?  I don’t see json referenced in GetResultTypeData method source.

string sql = "SELECT _id, CAST(extra_columns AS JSON) as extra_columns FROM hive.default.measures";PrestoCommand cmd = new PrestoCommand(sql, connection);PrestoDataReader rdr = cmd.ExecuteReader();


  Message: Test method Juniper.Test.Trino.TrinoClientTests.PrestoAdoRead threw exception: System.Data.CData.Presto.PrestoException: [500] Could not execute the specified command: Unknown datatype: JSON. ---> oro230j.TC: Unknown datatype: JSON.  Stack Trace: ZN.GetResultDataType(FormulaEvaluationContext )RqC.K(SqlFormulaColumn )RqC.mI(SqlTable , SqlColumn )Rod.C(SqlCollection`1 )Rod.Nd(LLB`2 )Roh.Nd(LLB`2 )KJ.U(SQLQuery , Int32 , RRq )KJ.d(IDataStatement , SQLQuery , QueryParameterCollection , Int32 , String , LeW )RUJ.ExecuteQuery(IDataStatement , QueryParameterCollection , Int32 )RUG.ExecuteQuery(IDataStatement , QueryParameterCollection , Int32 )<9 more frames...>PrestoCommand.ExecuteDataReader(CommandBehavior behavior)PrestoCommand.ExecuteDbDataReader(CommandBehavior behavior)DbCommand.ExecuteReader()PrestoCommand.ExecuteReader()<PrestoAdoRead>d__5.MoveNext() line 106--- End of stack trace from previous location where exception was thrown ---ExceptionDispatchInfo.Throw()TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)TaskAwaiter.GetResult()ThreadOperations.ExecuteWithAbortSafety(Action action)

2

Our SQL engine does not support casting to a JSON type at this time. However, this looks like a syntax that Presto does support so to work around the issue here you might want to use NativeQuery.

SELECT * FROM NativeQuery(‘SELECT id, CAST(extra_columns AS JSON) FROM [TableName]’)

You can read more about it here: https://community.cdata.com/editions-90/using-nativequery-568?tid=568&fid=90

In case you have any other questions or issues feel free to send those over at support@cdata.com or you can always submit a support case here.