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Re: Help with Explain Plan
Posted by: Corey Samuels
Date: April 22, 2010 09:53AM

Maybe I can whittle down what I believe is the issue:

A LEFT JOIN on a large (>15 million rows) table ON an indexed primary key column (profile_id) gives this in the EXPLAIN:

+----+-------------+------------+--------+---------------------------------+---------------------+---------+----------------------------+------+----------------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+------------+--------+---------------------------------+---------------------+---------+----------------------------+------+----------------------------------------------+
| 1 | PRIMARY | tr | ref | profile_id,post_id | profile_id | 9 | ejmr.to_profile_id | 19 | |

This is taking a long, long time (~8 mins) even though the key is correct the rows column says "19". Is there anything you can see in the EXPLAIN that points to the cause?

Any help is appreciated.

Thanks,
Corey

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