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    <p>You can't compress the data without having to uncompress it in order to search it - which is going to severely damage the performance. If the data really is changing that often (i.e. more than an average of 20 times per record) then it would be more efficient to for storage and retrieval to structure it as a series of changes:</p> <p>Consider:</p> <pre><code> CREATE TABLE profile ( id INT NOT NULL autoincrement, PRIMARY KEY (id); ); CREATE TABLE profile_data ( profile_id INT NOT NULL, attr ENUM('username', 'email', 'first_name' , 'last_name', 'website', 'avatar_url' , 'address', 'city', 'zip', 'phone') NOT NULL, value CARCHAR(255), starttime DATETIME DEFAULT CURRENT_TIME, endtime DATETIME, PRIMARY KEY (profile_id, attr, starttime) INDEX(profile_id), FOREIGN KEY (profile_id) REFERENCES profile(id) ); </code></pre> <p>When you add a new value for an existing record, set an endtime in the masked record. Then to get the value at a date $T:</p> <pre><code> SELECT p.id, attr, value FROM profile p INNER JOIN profile_date d ON p.id=d.profile_id WHERE $T&gt;=starttime AND $T&lt;=IF(endtime IS NULL,$T, endtime); </code></pre> <p>Alternately just have a start time, and:</p> <pre><code>SELECT p.id, attr, value FROM profile p INNER JOIN profile_date d ON p.id=d.profile_id WHERE $T&gt;=starttime AND NOT EXISTS (SELECT 1 FROM prodile_data d2 WHERE d2.profile_id=d.profile_id AND d2.attr=d.attr AND d2.starttime&gt;d.starttime AND d2.starttime&gt;$T); </code></pre> <p>(which will be even faster with the MAX concat trick).</p> <p>But if the data is not changing with that frequency then keep it in the current structure.</p>
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    1. POHow to optimise change history data for MySQL
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