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POAny way to speed up this query?
 

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  1. POAny way to speed up this query?
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    <p>This query is really slow. Takes between 9 and 10 seconds...</p> <pre><code>SELECT DISTINCT a.* FROM addresses a LEFT JOIN contacts c ON c.id = a.contact_id LEFT JOIN organizations o ON o.id = a.organization_id ORDER BY c.last_name, c.first_name, o.name LIMIT 0, 24 </code></pre> <p>If I comment out the <code>ORDER BY</code> clause the query runs much faster -- about 5 milliseconds. But I need the <code>ORDER BY</code> to support paging of the search results. And the users need the addresses to be sorted by contact and organization.</p> <hr> <p><strong>Table structure</strong></p> <pre><code>addresses --------- id int NOT NULL contact_id int # could be NULL organization_id int # could be NULL contacts -------- id int NOT NULL first_name varchar(255) last_name varchar(255) organizations ------------- id int NOT NULL name varchar(255) </code></pre> <p>They're all InnoDB tables.</p> <p>I have these indexes on the contacts table:</p> <pre><code> KEY `idx_contacts_first_name` (`first_name`), KEY `idx_contacts_last_name` (`last_name`), KEY `idx_contacts_first_name_last_name` (`first_name`,`last_name`) </code></pre> <p>And on the organizations table:</p> <pre><code> KEY `idx_organization_name` (`name`) </code></pre> <hr> <p><strong>Amount of data</strong></p> <pre><code>Addresses: 22,271 Contacts: 17,906 Organizations: 8,246 </code></pre> <hr> <p><strong>DESCRIBE output</strong></p> <pre><code>mysql&gt; DESCRIBE -&gt; SELECT DISTINCT a.* -&gt; FROM addresses a -&gt; LEFT JOIN contacts c -&gt; ON c.id = a.contact_id -&gt; LEFT JOIN organizations o -&gt; ON o.id = a.organization_id -&gt; ORDER BY c.last_name, c.first_name, o.name -&gt; LIMIT 0, 24; +----+-------------+-------+--------+---------------+---------+---------+--------------------------------------------+-------+---------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+---------------+---------+---------+--------------------------------------------+-------+---------------------------------+ | 1 | SIMPLE | a | ALL | NULL | NULL | NULL | NULL | 22387 | Using temporary; Using filesort | | 1 | SIMPLE | c | eq_ref | PRIMARY | PRIMARY | 4 | contactdb_v2_development.a.contact_id | 1 | Distinct | | 1 | SIMPLE | o | eq_ref | PRIMARY | PRIMARY | 4 | contactdb_v2_development.a.organization_id | 1 | Distinct | +----+-------------+-------+--------+---------------+---------+---------+--------------------------------------------+-------+---------------------------------+ 3 rows in set (0.00 sec) </code></pre>
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