22 • full-stack developer • learning Go
India
Joined April 2024
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why the hell is auto-scroll still not available on Instagram for iPad, @instagram ? 😭
it's 2026. how am i still manually scrolling reels?
Today I learned about database Connection Pooling.
Instead of opening and closing a database connection for every request, we maintain a pool of reusable connections.
Also learned why managing these pools becomes important when an application runs multiple backend instances.
↳ Each backend instance can have its own connection pool.
For example, 4 instances with 30 connections each can create 120 potential connections, even if the database allows only 100.
↳ What happens when all connections are occupied?
New requests have to wait until a connection becomes available. If they wait too long, they can time out.
↳ A request borrows an available connection, executes its database query, and returns the connection to the pool.
Another request can then reuse that same connection instead of creating a new one.
Learning System Design:
Spent some time learning about ACID today. The bank transfer example actually helped me understand why these properties matter.
A simple transfer involves more than just moving money from one account to another.
Here are the 4 things I learned 👇
Isolation = Transactions shouldn't interfere improperly.
Imagine two people transferring money from the same account simultaneously. The database must coordinate these transactions to prevent incorrect results.
Consistency = Database rules remain valid.
For example, if an account isn't allowed to have a negative balance, a transaction that violates this rule must be rejected.
Atomicity = All or Nothing.
When transferring ₹500, the database must either deduct it from Account A AND add it to Account B, or undo the entire transaction if something fails.
Learning System Design
Things I learned:
↳ API Gateway: Routes API requests and handles auth.
↳ Load Balancer: Distributes traffic across instances.
↳ Reverse Proxy: Forwards requests to backend servers.
Code and implementation next! 🚀
A Load Balancer distributes incoming requests across multiple instances of the same service.
It can also perform health checks and stop sending traffic to unhealthy instances.