How Sei's Eidos upgrade rebuilds storage while the chain runs

@SeiNetwork has begun rolling out Eidos, the storage track of its broader Giga upgrade, with the first phase already live on mainnet. Eidos is the upgrade that will take Sei's storage layer to Giga speed, and Giga is the series of upgrades designed to dramatically improve the Sei blockchain, making it much faster and giving it next-generation features to make it the optimal on-chain environment for trading. The overarching goal is ambitious: the multi-phase Giga plan targets sub-250ms block finality and industrial-grade throughput for decentralised finance. At the top of that target sits a throughput figure of 200,000 transactions per second.

Phase One: Separating EVM History

The first phase of Eidos reached Sei mainnet with the v6.6 release in August 2026, with EVM state beginning to move into its own database and a rebuilt pruning path shipping alongside it. Before this change, EVM state history and Cosmos native state shared a single database, forcing historical data reads to compete directly with live real-time transactions. The separation removes that bottleneck. The new architecture gives EVM state its own dedicated store, preventing historical queries from competing directly with live transaction processing and reducing database work imposed on non-EVM modules.

The pruning improvements are already measurable. The pruning changes reduced one cleanup process from between eight and 18 minutes to roughly five minutes during testing and operation. Node stability has also improved: nodes that could previously fall hundreds of blocks behind the chain tip remained within about 60 blocks after the change.

The upgrade is the storage component of a three-part architecture overhaul that also includes Autobahn for consensus and Ares for transaction execution. All three tracks are being rolled out in stages, with the chain continuing to produce blocks throughout.

What FlatKV and Lattice Hashing Change

Most blockchains verify state using a Merkle tree, a structure where a single change forces the recomputation of every hash above it in the tree. Eidos retires the Merkle tree for Sei's EVM state. Its replacement, a store called FlatKV, keeps state in a flat key-value layout where one change is one write. A lattice hash (LtHash) maintains a running fingerprint of the entire state that updates in constant time per change, without cascading recomputation, and the network keeps its ability to verify everything.

In practical terms, instead of recalculating a path of hashes through a Merkle tree, a node removes the contribution of the old value and adds the new one, leaving the amount of work per update unchanged as the state expands. This design keeps verification costs flat even as the chain grows.

FlatKV, LittDB and the off-node archival system will form the next stage as they arrive through later releases, and users and application developers do not need to take any action during the migration, with balances, smart contracts, historical records and existing RPC endpoints remaining available.

Sources:
Sei Labs: The Eidos Upgrade (Official Blog)
crypto.news: Sei starts phased Eidos upgrade to prepare network for 200,000 TPS
Sei Labs: Ares and Eidos, the first components of the Giga Upgrade, will go live in Sei 6.6