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Alex Rivera
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I'm trying to get an rough (order-of-magnitude) estimate of how long time the following query could take: mysql> EXPLAIN SELECT t1.col1, t1_col4 FROM t1 LEFT JOIN t2 ON t1.col1=t2.col1 WHERE col2=0 AND col3 IS NULL; +----+-------------+--------------------+------+---------------+------------+---------+-----------------------------+---------+--------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+--------------------+------+---------------+------------+---------+-----------------------------+---------+--------------------------+ | 1 | SIMPLE | t1 | ref | foobar | foobar | 4 | const | 9715129 | | | 1 | SIMPLE | t2 | ref | col1 | col1 | 4 | db2.t1.col1 | 42318 | Using where; Using index | +----+-------------+--------------------+------+---------------+------------+---------+-----------------------------+---------+--------------------------+ 2 rows in set (0.00 sec) mysql>
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