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copied!<p>You need only two fields in your <code>group by</code> (and if the field <code>event_id</code> is the primary key you only need <strong>that</strong> field.<br> Having group by to consider less fields should make your query faster.<br> You should only put <strong>functionally independent fields</strong> in the group by, listing functionally dependent fields there is non-nonsensical and a waste of time.<br> Fortunately MySQL does not require you to do this. </p> <pre><code>$scheduler->render_table("events LEFT JOIN tblfollowers ON events.id_user = tblfollowers.username WHERE events.status ='active' AND '$test' IN (tblfollowers.follower_id, events.id_user) <<-- maybe faster GROUP BY events.event_id, events.id_user <<-- only include unique key fields ORDER BY events.timestamp DESC" ,"event_id","start_date, start_date,event_name,details"); $scheduler->render_sql("SELECT event_id, start_date, end_date, event_name, details FROM events "); </code></pre> <p>See here for more info: <a href="http://rpbouman.blogspot.com/2007/05/debunking-group-by-myths.html" rel="nofollow">http://rpbouman.blogspot.com/2007/05/debunking-group-by-myths.html</a> </p> <p><strong>Why is it slow?</strong><br> Without the table definitions for tblfollowers and events it's hard to tell. </p> <p><strong>Use explain</strong><br> If you want to see where the bottleneck is, put an <code>EXPLAIN</code> in front of the select and paste the outcome in your question. </p> <pre><code>$scheduler->render_sql("EXPLAIN SELECT event_id, start_date, end_date, event_name, details FROM events "); </code></pre> <p><strong>Tacking on indexes does not help</strong><br> Use the output from <code>explain</code> to inform your decisions, adding indexes slows down your inserts and updates, and bloats your disk usage. </p>

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