Database / Azure Cosmos DB interview questions
What is the Cosmos DB free tier and what does it include?
The Cosmos DB free tier is a permanent (not time-limited) offering where every Azure account can have one Cosmos DB account with a perpetual free allocation, making it suitable for prototyping, side projects, and learning without ongoing costs.
The free tier allocation includes:
- 1,000 RU/s provisioned throughput — always free, every month, no expiration
- 25 GB of storage — always free, every month
This is enough for a small application with moderate load. For context: 1,000 RU/s can handle approximately 1,000 point reads per second, or roughly 200 writes per second for 1 KB documents. 25 GB covers millions of typical user profile documents.
Important constraints and conditions:
- Only one free tier account per Azure subscription. You cannot have multiple free tier accounts in the same subscription.
- Free tier must be selected at account creation — it cannot be applied to an existing paid account.
- Resources beyond the free allocation (above 1,000 RU/s or 25 GB) are billed at standard rates. For example, if you provision 4,000 RU/s, you pay for 3,000 RU/s and the first 1,000 are free.
- All APIs are eligible for the free tier — NoSQL, MongoDB, Cassandra, Gremlin, and Table.
- Multi-region replication multiplies throughput costs as usual, even for the portion covered by free tier.
The free tier is different from the 30-day Azure free trial credits. Free tier credits are perpetual and apply to the Cosmos DB account specifically, continuing even after the trial period ends — as long as you stay within the 1,000 RU/s and 25 GB allocations, you pay nothing.
Invest now in Acorns!!! 🚀
Join Acorns and get your $5 bonus!
Acorns is a micro-investing app that automatically invests your "spare change" from daily purchases into diversified, expert-built portfolios of ETFs. It is designed for beginners, allowing you to start investing with as little as $5. The service automates saving and investing. Disclosure: I may receive a referral bonus.
Invest now!!! Get Free equity stock (US, UK only)!
Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.
The Robinhood app makes it easy to trade stocks, crypto and more.
Webull! Receive free stock by signing up using the link: Webull signup.
More Related questions...
