[DRILL-5757] CONVERT_TO_JSON function is failed while using non-existence field as a parameter.

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.11.0
• Fix Version/s: 1.12.0
• Component/s: Execution - Data Types
• Labels: ready-to-commit
• Assignee: Vitalii Diravka
• Reporter: Vitalii Diravka
• Reviewer: Arina Ielchiieva
• Created: 31/Aug/17 16:11
• Updated: 03/Sep/17 06:55
• Resolved: 03/Sep/17 06:55

Description

Using of non-existence field as parameter (or field with null values across a whole batch) of CONVERT_TO_JSON function leads to failure.

simple.json

{"id": 0}

0: jdbc:drill:zk=local> select `id`, convert_to(`complex_field`, 'JSON') from dfs.`/tmp/simple.json`;
Error: SYSTEM ERROR: UnsupportedOperationException: Unable to get holder type for minor type [LATE] and mode [OPTIONAL]

Fragment 0:0

[Error Id: a13a1ed0-f8fe-4d4a-ba35-ab17c3a2f171 on vitalii-pc:31010] (state=,code=0)

The root cause of the issue and fix:
If there isn't a particular vector for the field, "NullExpression" is created as an argument for the Drill function. That argument can be replaced later in "ExpressionTreeMaterializer.visitFunctionCall()" with "TypedNullConstant" logical expression, but LATE type shouldn't be used for this case, the data type of the field is still unknown.

Note: the issue is reproduced not only for json (for example mongo or mapr-db json tables have the same issue)

Issue Links

• links to: GitHub Pull Request #929