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  1. PO
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    <p>My initial idea was to create a temporary table to hold (and index) the user_id that match the name, and use that to join against each link table. Unfortunately, in MySQL a temporary table can only be joined against ONCE in a query.</p> <p>The nasty workaround is to create a permanent table, adding the connection_id to the primary key so separate sessions do not get confused.</p> <pre><code>create table tt ( connection_id int not null, user_id int not null, firstname varchar(10) not null, lastname varchar(10) not null, primary key( connection_id, user_id ) ); </code></pre> <p>The following sequence would be repeated each time you need an answer:</p> <pre><code>delete from tt where connection_id = connection_id(); insert into tt SELECT connection_id(), user_id, firstname, lastname FROM users WHERE firstname LIKE '%Jenkz%' UNION SELECT connection_id(), user_id, firstname, lastname FROM users WHERE lastname LIKE '%Jenkz%'; </code></pre> <p>Next, your existing UNION is extended so that only the relevant user_id is pulled out:</p> <pre><code>SELECT 'writer' AS role, link_writers.user_id, link_writers.publication_id FROM link_writers JOIN tt ON tt.connection_id = connection_id() and tt.user_id = link_writers.user_id UNION SELECT 'editor' AS role, link_editors.user_id, link_editors.publication_id FROM link_editors JOIN tt ON tt.connection_id = connection_id() and tt.user_id = link_editors.user_id UNION SELECT 'publisher' AS role, link_publishers.user_id, link_publisher_groups.publication_id FROM link_publishers JOIN link_publisher_groups ON link_publisher_groups.publisher_group_id = link_publishers.publisher_group_id JOIN tt ON tt.connection_id = connection_id() and tt.user_id = link_publishers.user_id </code></pre> <p>Perhaps this will be an improvement because not every row of all the link tables is being pulled into the union.</p> <p>The EXPLAIN is a bit peculiar in that only 4 bytes of the index on tt is being used - where I would have expected all 8 bytes. Perhaps this is because I have so little data in tt.</p> <pre><code>*************************** 1. row *************************** id: 1 select_type: PRIMARY table: tt type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: const rows: 1 Extra: Using index *************************** 2. row *************************** id: 1 select_type: PRIMARY table: link_writers type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: test.tt.user_id rows: 1 Extra: Using index *************************** 3. row *************************** id: 2 select_type: UNION table: tt type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: const rows: 1 Extra: Using index *************************** 4. row *************************** id: 2 select_type: UNION table: link_editors type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: test.tt.user_id rows: 1 Extra: Using index *************************** 5. row *************************** id: 3 select_type: UNION table: tt type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: const rows: 1 Extra: Using index *************************** 6. row *************************** id: 3 select_type: UNION table: link_publishers type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: test.tt.user_id rows: 1 Extra: Using index *************************** 7. row *************************** id: 3 select_type: UNION table: link_publisher_groups type: ref possible_keys: PRIMARY key: PRIMARY key_len: 4 ref: test.link_publishers.publisher_group_id rows: 2 Extra: Using index *************************** 8. row *************************** id: NULL select_type: UNION RESULT table: &lt;union1,2,3&gt; type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: NULL Extra: 8 rows in set (0.00 sec) </code></pre>
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    1. POMySQL search for user and their roles
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    1. USMartin
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    1. COThis looks like a good "if all else fails" solution Martin, thanks for your work. I've now posted the EXPLAIN from my actual query if this offers any more insight?
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