TON splits its chain in two when traffic rises and merges it back later

A different approach to sharding

Most blockchains that support sharding fix the number of shards in advance. The Open Network (@ton_blockchain) takes a different path. TON dynamically splits workchains into halves when the transaction rate rises above a threshold, and merges them back when it falls below. The protocol calls this the Infinite Sharding Paradigm.

The core idea of the Infinite Sharding Paradigm is to treat each account, or smart contract, as if it existed in its own shardchain. Because maintaining hundreds of millions of individual blockchains is impractical, those account-chains are grouped into shardchains, where each shardchain block is effectively a collection of account-chain blocks assigned to that shard.

How splits and merges work in practice

Account placement after a split is determined by address. When load exceeds the threshold and validators decide to split a shardchain, all accounts whose address ID starts with a 0 bit are assigned to one shardchain, and those starting with a 1 bit go to the other. The number of shardchains in each workchain is always a power of two and can vary dynamically from 1 to 2^60.

Validators signal their intent to split or merge using want_split and want_merge flags alongside workchain configuration parameters. Once a decision is made, the split or merge takes effect after a delay of 100 seconds. If a split or merge event occurs, the affected shards pause until the next masterchain block.

Cross-shard communication is handled through a structured messaging system. Load is split among separate groups of validators, each processing accounts whose addresses share the same prefix. When one contract sends a message to another, if both contracts reside in the same shard the group processes the message immediately; if they are in different shards, the system routes the message between groups.

The division and merging process occurs automatically, adapting dynamically to changing network conditions without manual intervention. The result is a network architecture designed to handle growing user demand without requiring protocol-level changes to shard counts.

Sources
TON Docs: Blockchain Sharding
TON Docs: Infinity Sharding Paradigm and Lifecycle