[DRILL-7818] SplitPart (SPLIT_PART) UDF work correct only with one-row data

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.18.0
• Fix Version/s: 1.19.0
• Component/s: Functions - Drill
• Assignee: Unassigned
• Reporter: Mykhailo Surnyk
• Created: 10/Dec/20 16:28
• Updated: 16/Dec/20 14:27
• Resolved: 16/Dec/20 14:27

Description

SPLIT_PART UDF from https://github.com/apache/drill/blob/eb63eadda9a7836d70513e10caec4664c42a1237/exec/java-exec/src/main/java/org/apache/drill/exec/expr/fn/impl/StringFunctions.java#L389

Don't work for the query that returns two or more rows, for example:

SELECT SPLIT_PART(A, ' ', 1) FROM (SELECT 'key1 value1' as A UNION SELECT 'key2 value2'

will throw an error, but 

SELECT SPLIT_PART(A, ' ', 1) FROM (SELECT 'key1 value1' as A UNION SELECT 'key2 value2') limit 1

Will return the correct result.

It's reproducing also for real data without `union`, I add it's just for example.