Created
February 15, 2011 15:17
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explain et index
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//Affiche les index positionnés sur ma table | |
SHOW INDEX FROM MA_TABLE | |
SELECT | |
* | |
FROM | |
tblA, | |
tblB, | |
tblC | |
WHERE | |
tblA.col1 = tblB.col1 | |
AND tblA.col2 = tblC.col1; | |
And EXPLAIN for the query: | |
+-------+------+---------------+------+---------+------+------+-------------+ | |
| table | type | possible_keys | key | key_len | ref | rows | Extra | | |
+-------+------+---------------+------+---------+------+------+-------------+ | |
| tblA | ALL | NULL | NULL | NULL | NULL | 1000 | | | |
| tblB | ALL | NULL | NULL | NULL | NULL | 1000 | Using where | | |
| tblC | ALL | NULL | NULL | NULL | NULL | 1000 | Using where | | |
+-------+------+---------------+------+---------+------+------+-------------+ | |
see http://hackmysql.com/case4 |
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