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https://issues.apache.org/jira/browse/DRILL-7426?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16961297#comment-16961297
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Charles Givre commented on DRILL-7426:
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[~paul-rogers]. I wonder if it might be worthwhile to have something in Drill
where it ignores or does something other than dump the stack trace when it
encounters unreadable data? For instance, what if in this case, it read the
entire field as a string?
> Json support lists of different types
> -------------------------------------
>
> Key: DRILL-7426
> URL: https://issues.apache.org/jira/browse/DRILL-7426
> Project: Apache Drill
> Issue Type: Improvement
> Components: Documentation
> Affects Versions: 1.16.0
> Reporter: benj
> Priority: Trivial
>
> With a file.json like
> {code:json}
> {
> "name": "toto",
> "info": [["LOAD", []]],
> "response": 1
> }
> {code}
> A simple SELECT gives an error
> {code:sql}
> apache drill> SELECT * FROM dfs.test.`file.json`;
> Error: UNSUPPORTED_OPERATION ERROR: In a list of type VARCHAR, encountered a
> value of type LIST. Drill does not support lists of different types.
> {code}
> But there is an option _exec.enable_union_type_ that allows these request
> {code:sql}
> apache drill> ALTER SESSION SET `exec.enable_union_type` = true;
> apache drill> SELECT * FROM dfs.test.`file.json`;
> +------+---------------+----------+
> | name | info | response |
> +------+---------------+----------+
> | toto | [["LOAD",[]]] | 1 |
> +------+---------------+----------+
> 1 row selected (0.283 seconds)
> {code}
> The usage of this option is not evident. So, it will be useful to mention
> after the error message the possibility to set it.
> {noformat}
> Error: UNSUPPORTED_OPERATION ERROR: In a list of type VARCHAR, encountered a
> value of type LIST. Drill does not support lists of different types. .... SET
> the option 'exec.enable_union_type' to true and try again;
> {noformat}
> This behaviour is used for other error, example:
> {noformat}
> ...
> Error: UNSUPPORTED_OPERATION ERROR: This query cannot be planned possibly due
> to either a cartesian join or an inequality join.
> If a cartesian or inequality join is used intentionally, set the option
> 'planner.enable_nljoin_for_scalar_only' to false and try again.
> {noformat}
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