Constant ckb_constant::store::TX_INDEX_UPPER_BOUND

pub const TX_INDEX_UPPER_BOUND: u32 = 597 * 1000 / 72; // 8_291u32

This value is try to set tx key range as tight as possible, so that db iterating can stop sooner, rather than walking over the whole range of tombstones. empty_tx_size = 72