Alteryx-Core Data Transformation Practice Question
You have two streams of data: one with 100 rows and one with 50 rows. You want to match records based on a shared key. If you use a Join tool and want to keep all 100 rows from the left stream, even if no match is found in the right stream, which join type is required?
⚠ Common exam trap
Test-takers often select a standard Inner Join or Right Join when they need to preserve every record from the primary data stream regardless of matches.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Left Outer Join
A Left Outer Join is the specific relational operation that retains all records from the left input regardless of whether a corresponding key exists in the right input. This is critical for data completeness in reporting. If you were to use a standard Inner Join, you would inadvertently drop records that don't find a match, leading to an incomplete view of the primary dataset.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Inner Join
Why it's wrong here
An Inner Join only returns records that have matching keys in both the left and right inputs. Any record in the 100-row stream that does not have a corresponding key in the 50-row stream would be excluded, resulting in fewer than 100 rows.
- ✓
Left Outer Join
Why this is correct
A Left Outer Join preserves all records from the left input stream. If a match is found in the right stream, the data is joined; if no match exists, the right-side columns are populated with null values, ensuring the original 100-row count is maintained.
- ✗
Right Outer Join
Why it's wrong here
A Right Outer Join prioritizes the right input stream, ensuring all 50 records from the right side are preserved. This would not guarantee that all 100 records from the left side are kept, making it the incorrect choice for this specific business requirement.
- ✗
Full Outer Join
Why it's wrong here
A Full Outer Join returns all records from both streams, matching where possible. While this would keep the 100 left-side rows, it would also keep all 50 right-side rows, resulting in more records than required if the goal is only to maintain the left-side original count.
About these practice questions
Courseiva writes every Alteryx-Core question from scratch — 142 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Alteryx exam blueprint
This Alteryx-Core practice question is part of Courseiva's free Alteryx certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the Alteryx-Core exam.