Wells Fargo Data Engineer Interview Guide

The Wells Fargo data engineer loop, round by round: what each stage tests, example questions with the guidance interviewers actually score, the mistakes that sink strong candidates, and how to prepare.

Last updated: Proudly published by: Jeff Wahl

What the Wells Fargo loop tests: domains and difficulty

Our prediction of the question mix by domain and difficulty for this company's data engineer loop, from live listings and interview reports.

By domain
SQL
43%
6
Python
57%
8
By difficulty
Easy
57%
8
Medium
21%
3
Hard
21%
3

The domain and difficulty mix we predict for a Wells Fargo data engineer loop, across 14 problems. It updates as more Wells Fargo data lands.

Updated 14 predicted Wells Fargo problems

3 real Wells Fargo interview questions

Reported by candidates from real loops, tagged by domain, round, level, and year. Expand for what the round is scoring.

SQLL4 · 2024
Write a SQL query to display the total number of users, number of transactions, and total order amount per month for the year 2020
Onsite · sql
+

Expected approach: GROUP BY month extracted from transaction date, with COUNT(DISTINCT user_id) for users, COUNT(*) for transactions, and SUM(amount) for total order amount, filtered to 2020 using WHERE or EXTRACT/DATE_TRUNC. Tests month-level aggregation, date filtering, and multiple aggregate functions in a single query.

PythonL4 · 2024
Write a function is_subsequence(string1, string2) that returns True if string1 is a subsequence of string2, where all characters of string1 appear in string2 in the same relative order but not necessarily consecutively
Onsite · python
+

Expected approach: two-pointer technique — iterate through string2 with a pointer for string1, advancing the string1 pointer each time a character match is found; return True if string1 pointer reaches the end. Edge cases: empty string1 (always True), empty string2 with non-empty string1 (False). Example: is_subsequence("ace", "abcde") → True; is_subsequence("aec", "abcde") → False. Part of the coding assessment in the Data Engineer onsite loop.

PythonL3
Write a function is_subsequence(s1, s2) that returns True if string s1 is a subsequence of string s2, False otherwise
Online assessment
+

Try a Wells Fargo-style SQL round

Find every user active on 3 or more CONSECUTIVE days. This gaps-and-islands shape shows up in nearly every DE SQL round. Edit the query and run it against the seed data.

/* Users active on 3+ consecutive days. */
/* Hint: date minus a per-user ROW_NUMBER is constant within a streak. */
WITH streaks AS (
SELECT
user_id,
activity_date,
activity_date - CAST(
(ROW_NUMBER() OVER (
PARTITION BY user_id
ORDER BY activity_date
))
AS INT
) AS grp
FROM user_sessions
)
SELECT
user_id
FROM streaks
GROUP BY user_id, grp
HAVING COUNT(*) >= 3

Practice the Wells Fargo loop

The problems our model expects in this company's interview, grouped by round. Work the shapes that come up, not the ones that read well on a list.

Wells Fargo is hiring data engineers now

The roles behind this loop. Prep against the levels and locations they are actually filling.

Wells Fargo compensation and culture

The numbers, tech stack, and team structure live on the company overview.

Compare Wells Fargo with other data engineering employers

How the role, pay, and loop stack up against peer companies.

02 / Why practice

Prepare at Wells Fargo interview difficulty

  1. 01

    Reading a solution is not the same as writing one

    Every engineer who has frozen on a query they had read a dozen times knows the gap. The only preparation that closes it is producing the answer yourself, under time, before the interview does it for you

  2. 02

    76% of hiring managers reject on the coding task, not the resume

    From HackerRank's 2024 Developer Skills Report. Candidates who look strong on paper still fail the live screen if they haven't done timed, executable practice

  3. 03

    5 problem shapes cover 80% of data engineer loops

    Dedup, sessionization, top-N-per-group, slowly-changing dimensions, partition tricks. Writing the shapes by hand turns the unfamiliar into pattern recognition

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