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How to use chain state snapshots 📸
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How to use chain state snapshots 📸

The synchronization process from the genesis block can take many hours, or even days to complete as blockchains get longer and longer over time.

In circumstances where a faster synchronization is required, various snapshots of the fetchd chain state data are available for download, to more quickly bootstrap a node.

A snapshot refers to a specific point in time at which the state of a blockchain network is captured. It records the current state of all accounts, balances, smart contracts, and other data on the blockchain at that particular moment.

Snapshots are available for both mainnet and the most recent testnet. The URLs for them can be obtained from the active network ↗ī¸ page of our documentation.

Our aim is to update snapshots on a daily basis!

The example below uses the pruned mainnet snapshot, but can be adapted as required for full or archive nodes.

Example: using a snapshot

Stop your node

If you are already running fetchd, it is important that you stop it before proceeding.

If you have not already initialised your node, follow the instructions for joining a testnet ↗ī¸ then return to this page before starting fetchd.

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Remember to modify the information for the mainnet as appropriate!

Reset your node

  • If using fetchd ≤ 0.10.3: fetchd unsafe-reset-all

  • If using fetchd â‰Ĩ 0.10.4: fetchd tendermint unsafe-reset-all

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This will irreversibly erase your node's state database. Ensure you take whatever backups you deem appropriate before proceeding.

Download and install the snapshot

Many options are available here!

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The example below assumes a bash-like environment, uses a single connection for downloading, confirms the md5sum of the downloaded data against that of the original, and does not land the original compressed data to disk. This is a good starting point, but depending on your local environment you may wish to make adaptations that eg sacrifice disk space and extra md5sum complexity for the benefit of parallel downloads with aria2. This is entirely up to you! Let us know how you get on in the process!

# (optional) show the timestamp of the latest available snapshot
echo "Latest available snapshot timestamp : $(curl -s -I  https://storage.googleapis.com/fetch-ai-mainnet-snapshots/fetchhub-4-pruned.tgz | grep last-modified | cut -f3- -d' ')"
 
# download, decompress and extract state database
curl -v https://storage.googleapis.com/fetch-ai-mainnet-snapshots/fetchhub-4-pruned.tgz -o- 2>headers.out | tee >(md5sum > md5sum.out) | gunzip -c | tar -xvf - --directory=~/.fetchd
 
# (optional, but recommended) compare source md5 checksum provided in the headers by google, with the one calculated locally
[[ $(grep 'x-goog-hash: md5' headers.out | sed -z 's/^.*md5=\(.*\)/\1/g' | tr -d '\r' | base64 -d | od -An -vtx1 | tr -d ' \n') == $(awk '{ print $1 }' md5sum.out) ]] && echo "OK - md5sum match" || echo "ERROR - md5sum MISMATCH"
 
# (optional) show the creation date of the downloaded snapshot
echo "Downloaded snapshot timestamp: $(grep last-modified headers.out | cut -f3- -d' ')"

Restart your node

Again, this entirely depends on your local installation, but a simple example for mainnet might be the following:

fetchd start --p2p.seeds 17693[email protected]:36456,a575c681c2861fe945f77cb3aba0357da294f1f2@connect-fetchhub.fetch.ai:36457,d7cda986[email protected]:36458`.

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