CREATE SEQUENCE IF NOT EXISTS global_snowflake_id_seq;

CREATE OR REPLACE FUNCTION create_snowflake(shard_id INT DEFAULT 1)

RETURNS bigint

LANGUAGE 'plpgsql'

AS $$

DECLARE

our_epoch bigint := 1609459200;

seq_id bigint;

now_millis bigint;

result bigint:= 0;

SELECT nextval('global_snowflake_id_seq') % 1024 INTO seq_id;

SELECT FLOOR(EXTRACT(EPOCH FROM clock_timestamp()) * 1000) INTO now_millis;

result := (now_millis - our_epoch) << 22;

result := result | (shard_id << 9);

result := result | (seq_id);

return result;

END;

$$;