ipld-eth-server/db/migrations/00015_create_canonical_hash_finder_functions.sql

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MySQL
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-- +goose Up
-- +goose StatementBegin
-- returns the number of child headers that reference backwards to the header with the provided hash
CREATE OR REPLACE FUNCTION header_weight(hash VARCHAR(66)) RETURNS BIGINT
AS $$
WITH RECURSIVE validator AS (
SELECT block_hash, parent_hash, block_number
FROM eth.header_cids
WHERE block_hash = hash
UNION
SELECT eth.header_cids.block_hash, eth.header_cids.parent_hash, eth.header_cids.block_number
FROM eth.header_cids
INNER JOIN validator
ON eth.header_cids.parent_hash = validator.block_hash
AND eth.header_cids.block_number = validator.block_number + 1
)
SELECT COUNT(*) FROM validator;
$$ LANGUAGE SQL;
-- +goose StatementEnd
-- +goose StatementBegin
-- returns the id for the header at the provided height which is heaviest
CREATE OR REPLACE FUNCTION canonical_header(height BIGINT) RETURNS INT AS
$BODY$
DECLARE
current_weight INT;
heaviest_weight INT DEFAULT 0;
heaviest_id INT;
r eth.header_cids%ROWTYPE;
BEGIN
FOR r IN SELECT * FROM eth.header_cids
WHERE block_number = height
LOOP
SELECT INTO current_weight * FROM header_weight(r.block_hash);
IF current_weight > heaviest_weight THEN
heaviest_weight := current_weight;
heaviest_id := r.id;
END IF;
END LOOP;
RETURN heaviest_id;
END
$BODY$
LANGUAGE 'plpgsql';
-- +goose StatementEnd
-- +goose Down
DROP FUNCTION header_weight;
DROP FUNCTION canonical_header;