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Asked: 2026-06-04T16:25:39+00:00

I’ve created an insert only table for the purpose of speed and maintaining a

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I’ve created an insert only table for the purpose of speed and maintaining a history. It’s structure is very generic, and is as follows:

  `id` bigint(20) unsigned NOT NULL auto_increment,
  `user_id` bigint(20) unsigned NOT NULL,
  `property` varchar(32) NOT NULL,
  `value` longblob NOT NULL,
  PRIMARY KEY  (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1;

It’s simply a key/value table with a user_id assigned to it. This approach has its advantages as not all users have the same properties, so fields aren’t wasted in a table. Also, it allows for a rolling log of changes, since I can see every change to a particular property ever made by a user.

Now, since no deletes or updates ever occur in this table, I can assume that the greatest id will always be the newest entry.

However, I want to select multiple properties at once, for example ‘address1’, ‘address2’, ‘city’, ‘state’, and I want each to be the entry of it’s type with the highest id.

So, if they have changed their ‘state’ property 8 times, and ‘city’ property 4 times, then I’d only want a SELECT to return the latest of each (1 state and 1 city).

I’m not sure this can even be done efficiently with this type of a table, so I’m open to different table approaches.

Please, let me know if I need to produce anymore information or clarify my question better.

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I tried the following, but, there could be 3 rows of ‘address1’ changes after the last ‘address2’ change. Perhaps using a GROUP BY will work?

SELECT property, value FROM kvtable WHERE user_id = 1 AND (property = 'address1' OR property = 'address2') ORDER BY id

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1 Answer

  1. Editorial Team

    Assuming your ids are incremental integers and you have not manually specified them out of order, you can do this with a few MAX() aggregates in a subquery. The point of the subquery is to return the latest entry per property name, per user. That is joined against the whole table to pull in the associated property values. Essentially, the subquery discards all rows which don’t have a max(id) per group.

    SELECT kvtable.* 
FROM
  kvtable
  JOIN (
    SELECT
      MAX(id) AS id,
      user_id,
      property
    FROM kvtable
    /* optionally limit by user_id */
    WHERE user_id = <someuser>
    GROUP BY user_id, property
  ) maxids ON kvtable.id = maxids.id
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