Oracle - Server DBA

Question: Search in a Rotated Sorted Array Given a sorted array that has been rotated at an unknown pivot, I had to find the index of a target element in O(log n) time. For example:

Input: nums = [4,5,6,7,0,1,2], target = 0
Output: 4

I first explained the modified binary search approach, identifying which half of the array is sorted in each iteration and adjusting the search boundaries accordingly.

I handled edge cases like:

Array with a single element.

Target not present.

Fully sorted without rotation.

Wrote the code and did a dry run for multiple scenarios.

After completing the coding, the interviewer switched to resume-based deep questions:

Detailed discussion on my Machine Learning and Generative AI projects, including data preprocessing steps, choice of algorithms, and evaluation metrics.

Questions on my Linux file descriptors and system calls project — asked how file I/O works at the OS level.

Behavioral questions like:

A time when a project didn’t go as planned — what did you do?

How do you approach optimizing code for both runtime and memory efficiency?

Round 2 – Database Design This round was a system design interview focused on databases.

Task: Design a Database for a Restaurant Management System Requirements included:

Table reservations (handling concurrent booking requests).

Menu management (items, categories, prices).

Order tracking (order details, status updates).

Billing and payment records.

Staff management (roles, schedules).

I began by identifying entities: Customer, Table, Reservation, MenuItem, Order, OrderItem, Bill, Staff. Then I drew an ER diagram and explained relationships:

One-to-many: Customer → Reservation.

Many-to-many: Order ↔ MenuItem via OrderItem.

One-to-one: Order → Bill.

Follow-up questions included:

How would you prevent two users from booking the same table simultaneously? → Explained database transactions and row-level locking.

How would you scale for multiple branches of the restaurant? → Talked about sharding, read replicas, and separating menu service from reservation service.

How to handle cancellations and refunds? → Discussed using a status field in Reservation and Bill tables.

I also highlighted the use of indexes on frequently queried columns and discussed how to maintain consistency in a concurrent environment.