[Batch Rewards] Orderbook Query for Batch Rewards (#26)

As part of #27 we implement the Raw Orderbook query that will be used to extract the data to be synced with Dune. The follow up to this PR will implement the python script executing this that is also responsible for transforming it into the JSON files being uploaded to Dune's AWS bucket.

Solvers are expected to change their rewards to the following

reward(txHash) = observedQuality - referenceScore

where observedQuality = Surplus + Fee

Furthermore, the reward per batch is planned to be capped by [-E, E + executionCosts]  (E = 0.01 ETH)

This query joins several tables in order to provide all terms required to evaluate the reward (namely surplus, fee, execution_cost, reference_score). winning_score is included too which is not really necessary but more for transparency.

Furthermore, it is expected that if the total allocated rewards for each accounting period are not reached, then we are to distribute the remaining funds according to the solver participation (found also as a field returned by this query).

src/sql/orderbook/batch_rewards.sql

@@ -0,0 +1,57 @@
+WITH observed_settlements AS (
+SELECT
+    -- settlement
+    tx_hash,
+    solver,
+    -- settlement_observations
+    block_number,
+    effective_gas_price * gas_used AS execution_cost,
+    surplus,
+    fee,
+    -- auction_transaction
+    auction_id
+FROM settlement_observations so
+JOIN settlements s
+  ON s.block_number = so.block_number
+  AND s.log_index = so.log_index
+JOIN auction_transaction at
+  ON s.tx_from = at.tx_from
+  AND s.tx_nonce = at.tx_nonce
+WHERE block_number > {{start_block}} AND block_number <= {{end_block}}
+),
+
+reward_data AS (
+  SELECT
+    -- observations
+    tx_hash,
+    coalesce(
+      solver,
+      -- This is the winning solver (i.e. last entry of participants array)
+      participants[array_length(participants, 1)]
+    ) as solver,
+    -- Right-hand terms in coalesces below represent the case when settlement
+    -- observations are unavailable (i.e. no settlement corresponds to reported scores).
+    -- In particular, this means that surplus, fee and execution cost are all zero.
+    -- When there is an absence of settlement block number, we fall back
+    -- on the block_deadline from the settlement_scores table.
+    coalesce(block_number, block_deadline) as block_number,
+    coalesce(execution_cost, 0) as execution_cost,
+    coalesce(surplus, 0) as surplus,
+    coalesce(fee, 0) as fee,
+    surplus + fee - reference_score AS payment,
+    -- scores
+    winning_score,
+    reference_score,
+    -- participation
+    participants
+FROM settlement_scores ss
+-- If there are reported scores,
+-- there will always be a record of auction participants
+JOIN auction_participants ap
+  ON os.auction_id = ap.auction_id
+  -- outer joins made in order to capture non-existent settlements.
+LEFT OUTER JOIN observed_settlements os
+  ON os.auction_id = ss.auction_id
+)
+
+SELECT * FROM reward_data