| A nested loop join joins two tables p and q using this algorithm ... for each row rp in table p for each row rq in table q if rp and rq satisfy the join condition output the comjoined rows The algorithm ... - needs rowcountp * blockcountq + blockcountp block transfers, and - needs rowcountp + blockcountp seeks. - runs in O(|rowcountp||rowcountq|) I/Os. It can be improved to a block nested loop by using read blocks: for each blockp in p for each row in q for each row in blockq if the rows the join condition output the conjoined rows For more see https://mariadb.com/kb/en/mariadb/block-based-join-algorithms/ |