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From Prabhakar Bhosaale <bhosale....@gmail.com>
Subject Json Schma change error
Date Fri, 24 Sep 2021 11:36:02 GMT
Hi Team,
I am getting following error while querying JSON file

"(java.lang.Exception) UNSUPPORTED_OPERATION ERROR: Schema changes not
supported in External Sort."

I have identified the root cause as one of the column has NULL value for
certain rows and STRING value for certain rows

I am trying to find out How drill decides the datatype of columns and
identify the schema changes.

 I tried following changes in data and got different results.

Case 1  - If I remove order by clause in the query then I don't the error.
Point to note, this specific column is not part of order by clause. But it
is part of select list

Case 2 - If I keep only two rows in file, one with NULL data and other with
STRING data for given column then no error. Query returns the data
successfully

Case 3 - I change the value of given column in first to from NULL to empty
string that is two double quotes then no error

Previously somewhere I has read that drill reads initial certain rows of
JSON and decides the datatype but not able to find the same now in the
documentation.

Thanks and Regards
Prabhakar

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