[DRILL-2354] Documentation for Concat Function & Concat Operator

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Component/s: Documentation
• Assignee: Kris Hahn
• Reporter: Sean Hsuan-Yi Chu
• Created: 02/Mar/15 17:37
• Updated: 11/Sep/15 18:31
• Resolved: 24/Apr/15 21:18

Description

In Drill, we have two ways to concatenate Strings:
1. Concat Function: concat(c1, c2, c3, ...)
2. Concat Operator: c1 || c2 || c3 || ...

They are doing same thing except for dealing with NULL:
1. For concat function, NULL is treated as empty string

2. For concat operator: if any input is NULL, output NULL (no matter what other columns are)

These are subtle difference and would be better to be documented.
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Some discussion can be found from DRILL-2328

Issue Links

• duplicates: DRILL-1877 Throw unsupported error message for || operator early in the parsing stage