CREATE OR REPLACE FUNCTION old_to_new(old_id TEXT) 
RETURNS TEXT AS $$
DECLARE
    number NUMERIC;
    timestamp_seconds NUMERIC;
    timestamp_milliseconds NUMERIC;
    random NUMERIC;
    new_number NUMERIC;
    ulid TEXT;
BEGIN
    -- Convert hexadecimal to numeric
    number := ('x' || old_id)::bit(128)::numeric;
    
    -- Shift by 8 bytes to get the timestamp in seconds
    timestamp_seconds := number >> 64;
    timestamp_milliseconds := timestamp_seconds * 1000;
    
    -- The first 8 bytes are treated as the random part of the ULID
    random := number & ((1::numeric << 64) - 1);
    
    -- Shift the timestamp by 80 bits to make room for the random part
    new_number := (timestamp_milliseconds << 80) | random;
    
    -- Convert to base32 encoding (simplified version, might need adjustment)
    ulid := encode(new_number::bytea, 'base64');
    
    RETURN ulid;
END;
$$ LANGUAGE plpgsql;