Epoch

An epoch is a unit of time when validators of the network remain constant.
epoch 是网络验证器保持不变的时间单位。

testnet和mainnet的epoch 持续时间约为12小时或43200秒。
您可以通过查询genesis_config RPC端点并搜索epoch_length来查看此设置。（https://docs.near.org/docs/develop/front-end/rpc\#genesis-config）
Nodes garbage collect blocks after 5 epochs unless they are archival nodes.

HTTPie Query:

http post https://rpc.mainnet.near.org jsonrpc=2.0 id=dontcare method=EXPERIMENTAL_genesis_config

Example Response:

{ 
    "id": "dontcare",
    "jsonrpc": "2.0",
    "result": { 
        "avg_hidden_validator_seats_per_shard": [
            0
        ],
        "block_producer_kickout_threshold": 90,
        "chain_id": "mainnet",
        "chunk_producer_kickout_threshold": 90,
        "dynamic_resharding": false,
        "epoch_length": 43200, // <---------- EPOCH duration in seconds
        "fishermen_threshold": "340282366920938463463374607431768211455",
        "gas_limit": 1000000000000000,
        "gas_price_adjustment_rate": [
            1,
            100
        ],
        "genesis_height": 9820210,
        "genesis_time": "2020-07-21T16:55:51.591948Z",
        "max_gas_price": "10000000000000000000000",
        "max_inflation_rate": [
            0,
            1
        ],
        // ---- snip ----
}