Interview guides · Eskenazi Health

Eskenazi Health Software Engineer Interview Guide

Eskenazi Health Software Engineer interview guide: reported rounds, questions and how candidates describe the process.

The 60-second brief

The role of a Software Engineer at Eskenazi Health is pivotal in driving technological innovations that enhance patient care and streamline operational efficiency. As a member of this dedicated team, you will contribute to critical projects that impact the healthcare delivery system, developing software solutions that are reliable, scalable, and user-friendly. This position plays a key role in transforming healthcare through technology, ensuring that the organization can harness data and digital tools effectively to improve patient outcomes. Your work will directly influence various products and systems used across Eskenazi Health, including electronic health records (EHR), billing systems, and custom software solutions that support clinical and administrative functions.

This guide is scoped to a Software Engineer candidate at Eskenazi Health.

Focus areas

ETL (Extract, Transform, Load)
SSIS (SQL Server Integration Services)
Data Integration

The Eskenazi Health interview process

Eskenazi Health candidates report 3 rounds over 3-5 weeks. The stages below are what candidates describe, not a published process.

Screening Interview

Initial interview to assess candidate's background and fit for the role.

What to demonstrate

Initial interview to assess candidate's background and fit for the role
Depth in ETL (Extract, Transform, Load)

How to prepare

Answer aloud and timed: What programming languages are you most proficient in?
Answer aloud and timed: Can you explain the software development lifecycle?

Technical Interviews

One or more interviews that may include coding assessments or problem-solving scenarios.

What to demonstrate

One or more interviews that may include coding assessments or problem-solving scenarios
Depth in ETL (Extract, Transform, Load)

How to prepare

Answer aloud and timed: Describe a challenging technical problem you faced and how you solved it.
Answer aloud and timed: How do you ensure the quality and maintainability of your code?

Behavioral Interviews

Interviews focusing on interpersonal skills and team dynamics.

What to demonstrate

Interviews focusing on interpersonal skills and team dynamics
Depth in ETL (Extract, Transform, Load)

How to prepare

Prepare three examples from your own work, each with a decision you made and an outcome you can quantify.
Re-read the description of the behavioral interviews above and write down what you would ask to confirm before it.

Where candidates lose points

Align with Company Values

Emphasize how your personal values reflect those of Eskenazi Health. This alignment is crucial for cultural fit.

Communicate Clearly

Practice articulating technical concepts simply and clearly, especially when discussing your experiences or projects.

Prepare for Behavioral Questions

Use the STAR method (Situation, Task, Action, Result) to structure your responses to behavioral questions effectively.

Engage with the Mission

Be prepared to discuss why you are passionate about healthcare technology and how it drives your work.

Questions & practice

Write a function to reverse a linked list.

Medium · Coding / Algorithms

Approach

Restate the input: its shape, its size, and what is guaranteed about it.
Name the brute-force solution and its complexity before improving on it.
Choose the data structure from the access pattern, not from familiarity.
State the target complexity and say which constraint rules the naive version out.

Follow-up

How does this change if the input no longer fits in memory?
What is the worst case, and how likely is it on real data?

How would you implement a search algorithm? Describe its time complexity.

Medium · Coding / Algorithms

Approach

Restate the input: its shape, its size, and what is guaranteed about it.
Name the brute-force solution and its complexity before improving on it.
Choose the data structure from the access pattern, not from familiarity.
State the target complexity and say which constraint rules the naive version out.

Follow-up

How does this change if the input no longer fits in memory?
What is the worst case, and how likely is it on real data?

Can you explain the differences between a stack and a queue?

Medium · Coding / Algorithms

Approach

Restate the input: its shape, its size, and what is guaranteed about it.
Name the brute-force solution and its complexity before improving on it.
Choose the data structure from the access pattern, not from familiarity.
State the target complexity and say which constraint rules the naive version out.

Follow-up

How does this change if the input no longer fits in memory?
What is the worst case, and how likely is it on real data?

How do you approach optimizing code for performance?

Medium · Coding / Algorithms

Approach

Restate the input: its shape, its size, and what is guaranteed about it.
Name the brute-force solution and its complexity before improving on it.
Choose the data structure from the access pattern, not from familiarity.
State the target complexity and say which constraint rules the naive version out.

Follow-up

How does this change if the input no longer fits in memory?
What is the worst case, and how likely is it on real data?

Given a dataset, how would you implement data visualization techniques?

Medium · Coding / Algorithms

Approach

Restate the input: its shape, its size, and what is guaranteed about it.
Name the brute-force solution and its complexity before improving on it.
Choose the data structure from the access pattern, not from familiarity.
State the target complexity and say which constraint rules the naive version out.

Follow-up

How does this change if the input no longer fits in memory?
What is the worst case, and how likely is it on real data?

Write the update path that detects a concurrent edit

Medium · optimistic concurrency · transactional outbox · audit history

resource carries version INT NOT NULL DEFAULT 1. resource_revision holds revision_id, resource_id, version, actor_user_id, change_kind, patch JSONB, request_id, created_at with UNIQUE (resource_id, version). outbox_event holds aggregate_type, aggregate_id, aggregate_version, event_type, payload, status. A PUT carries the version the client read. Write the exact statements for the single transaction that applies the edit, records the revision and enqueues 'resource.updated', and give the handler's branch on zero affected rows. Then say what PostgreSQL 16 does under READ COMMITTED when two of these updates hit one row at once.

Approach

One transaction, three writes, no network call inside it: UPDATE resource SET title = $3, version = version + 1, updated_at = now() WHERE resource_id = $1 AND tenant_id = $4 AND version = $2; then INSERT the resource_revision row at version $2 + 1; then INSERT the outbox_event row at the same aggregate_version. The event goes to a table rather than a broker because no transaction spans both.
Branch on the affected-row count before doing anything else. Zero has three causes — stale version, wrong tenant, row gone — so re-read once and map to 409 carrying the current version, or 404 for an id outside the caller's tenant, which also stops the endpoint confirming that another tenant's id exists.
State the engine behaviour instead of assuming it. Under READ COMMITTED the second UPDATE blocks on the row lock, and when the first commits PostgreSQL re-evaluates the WHERE clause against the newly committed row, so the version predicate now fails and the statement reports zero rows. Under REPEATABLE READ the identical collision raises SQLSTATE 40001 instead, so the handler must fold both shapes into one conflict response.
Keep UNIQUE (resource_id, version) even though the predicate already serialises writers. It is what makes a lost update unwritable if any other path ever reaches the revision table, and it converts a logic bug into 23505 rather than into a silently missing history row.

Follow-up

A client sends the version it read ten minutes ago and the resource has moved three versions. What is in your 409 so it can resolve the conflict without a full re-fetch?
Two editors, two disjoint fields, no overlap. Does your answer still refuse the second write, and should it?

Explain why the owner filter ignores the listing index

Medium · composite index · query plans · sort elimination

The only index on resource is (tenant_id, status, updated_at DESC, resource_id DESC). A new endpoint returns one user's resources across all statuses, newest created first: WHERE tenant_id = $1 AND owner_user_id = $2 ORDER BY created_at DESC LIMIT 20. On a tenant with 2M rows it takes 900 ms and EXPLAIN shows a sort above a large scan. Explain precisely why the existing index cannot serve it, give the index that can, and state which of these the new index still will not help: owner_user_id alone across tenants; the same query ordered by updated_at. PostgreSQL 16.

Approach

Separate the two jobs an index does. For filtering, a composite btree is seekable only on a left prefix, so with no predicate on status the scan can at best range over tenant_id and test owner_user_id per row; PostgreSQL 16 has no btree skip scan to jump the unconstrained column.
For ordering, the index is sorted by (status, updated_at) within a tenant and not by created_at, so the LIMIT cannot stop early: every matching row is read and then sorted. That is the 'Sort Method: top-N heapsort' line, and it is why the plan reads 2M rows to answer with 20.
Derive the replacement from the access path — equality, equality, then the ordering column: CREATE INDEX CONCURRENTLY ON resource (tenant_id, owner_user_id, created_at DESC). The scan seeks to the (tenant, owner) range and walks 20 entries in order, so the Sort node disappears along with the row-read.
Treat INCLUDE (title, status) as conditional, not free. An index-only scan still visits the heap for any row whose page is not marked all-visible, so on a table taking 1.2k writes/second the win depends on autovacuum keeping the visibility map current, and the wider index costs more on every insert.

Follow-up

90% of rows are status='active'. Would a partial index WHERE status = 'active' change your answer, and for which of the three queries?
A dashboard runs this for 40 owners in one page load. What changes about the design?