Description

Currently a op-geth node has two kinds of state world: MPT and snapshot. MPT(Merkle Patricia Tries) is a tree-structured state world. The key function of MPT is to generate the state root to ensure state consistency, while the query/commit on MPT is quite slow. Snapshot is a flattened key-value-based state world. Snapshot provides fast queries and commits. The storage size of the snapshot increases slowly even with a large transaction volume. Snapshot is usually used for block processing, while MPT is used for state verification.

In order to lower the hardware requirement, we introduce the fast node. The fast node will do block processing with snapshot, it will do all verification against blocks except state root.

The fast node doesn’t need to store MPT, so the storage and computation requirement will be much lower.

Since the fast node don'st store the MPT, we can't verify the state root mentioned above. We called it insecure-no-tries. But it should be reliable since we compared the diff layers of the fast node and normal node, it's identical.

It's only encouraged to use the fast node for the normal rpc nodes to reduce costs and improce the syncing performance.

Command

1. Fast Node

If you want to enable the fast node, you can add --allow-insecure-no-tries in the command.

 ./geth --config ./config.toml --datadir ./node --syncmode full  --allow-insecure-no-tries

2. Prune

If you want to prune the MPT state, you can also prune the node:

./geth snapshot insecure-prune-all --datadir ./datadir ./genesis.json

Performance

We compared the performance of the fast node and normal node by starting two nodes in full sync mode from the genesis of mainnet.

You can refer to the above image, the fast node finish the sync before the normal node more than two days.

Rationale

To lower the cost of the geth nodes and improve the syncing performance.

Example

N/A

Changes

Notable changes:

• add --allow-insecure-no-tries in command line
• add insecure-prune-all command to prune MPT state