How can we retrieve SD from cardano-node / db?

[jpraynaud]

How can we retrieve the stake distribution from the Cardano node?

There are 3 solutions that we could deploy:

• they also apply to retrieving the current epoch
• we will deploy solutions 1 and 2 at first and see if we need to investigate further solution 3

1. Use the cardano-cli:

• Difficulty: easiest solution to implement
• Add a binary of the cardano-cli in the docker image produced
• Use the query stake-distribution command
• Parse the returned tabular file that retrieves the SPO poolIds and their associated stake shares as in this example

                           PoolId                                 Stake frac
------------------------------------------------------------------------------
pool1qqyjr9pcrv97gwrueunug829fs5znw6p2wxft3fvqkgu5f4qlrg   2.493e-3
pool1qqfnw2fwajdnam7xsqhhrje5cgd8jcltzfrx655rd23eqlxjfef   2.164e-5
pool1qqnjh80kudcjphrxftj74x22q3a4uvw8wknlxptgs7gdqtstqad   8.068e-7
pool1qquwwu6680fr72y4779r2kpc7mxtch8rp2uhuqcc7v9p6q4f7ph   7.073e-7
pool1qpqvz90w7qsex2al2ejjej0rfgrwsguch307w8fraw7a7adf6g8   2.474e-11
pool1qptl80vq84xm28pt3t2lhpfzqag28csjhktxz5k6a74n260clmt   5.600e-7
pool1qpuckgzxwgdru9vvq3ydmuqa077ur783yn2uywz7zq2c29p506e   5.161e-5
pool1qz2vzszautc2c8mljnqre2857dpmheq7kgt6vav0s38tvvhxm6w   1.051e-6

• Drawback: the stake shares are cut with 3 significant decimals digits whereas we would need a greater precision
• Question: is the stake share enough information to feed the mithril-core library or do we also need to retrieve the total stakes supply?

2. Use the db-analyser:

• Difficulty: harder but not too complicated solution to implement (required to move to production)
• Create a custom cli that polls these information from the ledger states
• Do the same work as with solution 1, but with a custom made cli
• Advantage: Enables the full precision in the stake shares computation

3. Use oura:

• Difficulty: Hard, possible but maybe not implemented at first
• Use it as a separate cli or embedded in the Mithri nodes
• This solution provides a streaming of events occurring on the Cardano chain
• The streaming can start at a specific point on the Cardano chain
• The stream of events is sent into one of the predefined sinks (if we want to keep a light footprint of the Mithril node, webhook or file logging is preferable)
• Events related to stake registration/delegation/deregistration/... can be tracked (see details here)
• If we rely on the previously signed (by Mithril) stake distribution, we can incrementally compute the stake distribution
• Drawback: We need to re implement the stake distribution formula from the Cardano node