One of the cool things that attracted me to the SUI chain is the working manner of transactions, so in this article, we are going to get some knowledge about how transactions work in the SUI blockchain. Every transaction in Sui explicitly lists which objects it will read or modify. Because each object is independent, the Sui validators can easily check the list of objects for each incoming transaction​. This helps the system decide which transactions can run simultaneously:

• Independent transactions (no overlapping objects): If two transactions involve completely different objects, they do not conflict with each other. Sui knows these won’t interfere, so it can execute them at the same time in parallel​. For example, one transaction might update Alice’s coin object while another might transfer Bob’s NFT object – since these are separate objects, there’s no need to wait for one before doing the other.
• Conflicting transactions (shared objects): If two transactions try to use the same object, they conflict and cannot be executed at the exact same moment. Sui will handle this by ordering and executing those particular transactions one after the other to avoid any confusion or double-spending​. In this case, the network’s consensus mechanism comes into play to decide a fair order for the transactions that touch the same data. Only the transactions that conflict are ordered; all other independent transactions can proceed in parallel without waiting.

In essence, Sui’s transaction model separates “simple” transactions from “dependent” ones. Simple transactions that affect only a single owner’s objects can often be processed very quickly without involving the whole network in heavy coordination​. More complex transactions (for example, ones interacting with a shared smart contract object that many users might use) go through a traditional ordering process (consensus) to ensure they don’t conflict with each other​. This way, Sui only uses global consensus when it’s truly needed, and it can let most transactions fly through concurrently when there are no overlaps in the data they touch.

Parallel Execution in Sui vs. Traditional Blockchains

On traditional blockchains like Bitcoin or Ethereum, transactions are processed sequentially (one after the other). Even if two transactions have nothing to do with each other, a sequential system will still put one in line behind the other, creating unnecessary waiting​. This is like having a single checkout register at a store – even customers buying different items must stand in the same queue. It causes congestion and slows things down during busy periods​. Sui takes a different approach by allowing the parallel execution of transactions. This is analogous to having many checkout counters open: multiple transactions can be handled at the same time as long as they are independent, which vastly improves throughput and efficiency​. Because of Sui’s object-centric design, operations on one object do not impact or delay operations on another object​ . Validators in the Sui network can leverage multiple CPU cores and threads to execute several transactions simultaneously, much like processing multiple tasks in parallel on a computer. The result is a significant boost in scalability – Sui can handle a large number of transactions per second without breaking a sweat​. Tests have demonstrated that Sui’s approach can support massive throughput (on the order of hundreds of thousands of transactions per second) thanks to this parallelism​. Equally important, parallel execution reduces latency for individual transactions, meaning users see their transactions confirmed faster because they aren’t stuck waiting behind unrelated transactions​. Overall, Sui’s parallel execution model eliminates the bottlenecks that plague single-threaded (sequential) blockchains, enabling the network to scale up and handle workloads that would overwhelm traditional designs​.

Finality and Confirmation Speed

Finality refers to how quickly a transaction is irreversibly confirmed (i.e. once confirmed, it won’t be reverted). Sui is designed for quick finality, often reaching confirmation in a fraction of a second​. In practice, a typical Sui transaction can be confirmed in around 300–500 milliseconds (well under one second) once it’s processed – essentially near-instant for the user. This is much faster than many older blockchains. For comparison, Ethereum’s network usually needs on the order of several seconds to minutes to truly finalize a transaction (Ethereum blocks are around ~12 seconds apart, and it may take a couple of blocks or more for high confidence), while Bitcoin might require dozens of minutes (due to 10-minute block times and multiple confirmations) for a transaction to be considered final. Sui’s modern consensus and parallel execution give it a major speed advantage: transactions on Sui are confirmed almost immediately after you send them​. There’s no long wait for a new block to include the transaction or for multiple confirmations. In short, Sui provides sub-second finality, which means users can send a transaction and see it permanently settled right away. This fast confirmation is especially beneficial for applications like gaming, real-time finance, or retail payments, where waiting even tens of seconds could be too slow. Sui delivers confidence to the user quickly, making the blockchain feel much more responsive compared to traditional chains.