Navigating the Jungle of Distributed System: CAP vs. PACELC

Divyanshu
2 min readFeb 26, 2024

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Hey there, fellow explorer of the digital wilderness! Today, we’re embarking on an adventure into the intriguing world of distributed system. But fear not, we’re equipped with a trusty map called the CAP theorem… and its cooler cousin, the PACELC theorem!

CAP: Consistency, Availability, Partition Tolerance

Let’s start with CAP. Picture a big campfire where we’re roasting sweet potatoes(our precious data). Now, imagine our campsite has two tents (nodes) for storing these sweet potatoes. Suddenly, a river (network) divides our camp in two. Uh-oh! We have to decide: Do we ensure that every camper (user) gets the same perfectly roasted sweet potato(consistent data) or do we make sure that everyone gets a sweet potato, even if it’s not perfectly roasted (available data)? It’s a tough choice!

PACELC: Partition, Availability, Consistency, Else, Latency, Consistency

Now, let’s enter the realm of PACELC. We’re still in our camp, but the river has dried up (no partition!). Hooray! Now, we face a different challenge: time. We’re surrounded by three tents (nodes), and we must decide how long it takes for everyone to get their sweet potatoes.

Option 1: Low Latency (Fast Food Drive-Thru) When someone orders a sweet potato at Tent 1, they get it ASAP, even if it’s not perfectly roasted. Tent 2 and Tent 3 might take a bit longer to catch up, but eventually, everyone gets a sweet potatoes. This is like hitting up a fast-food joint — quick but maybe not the best quality sweet potatoes (eventual consistency).

Option 2: Strong Consistency (Gourmet sweet potatoes Chef) When someone orders a sweet potatoes at Tent 1, they wait patiently until all three tents have perfectly roasted sweet potatoes ready. Sure, it takes longer, but everyone gets the same gourmet experience. This is like waiting for a gourmet chef to whip up a masterpiece — takes time, but oh-so-worth-it (strong consistency).

In Conclusion…

Choosing between CAP and PACELC is like navigating through a dense jungle of trade-offs. Neither theorem can perfectly guide us through every twist and turn, but they give us valuable tools to make decisions.

Remember, the journey of building distributed system is an adventure full of complexities and surprises. So, let’s keep exploring, learning, and maybe toasting a few sweet potatoes along the way!

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