This is a serious bug, that gave us headaches when using import/export. The bug is real, and can easily be reproduced, by doing two small imports (single row) consecutively. Feedback would be appreciated.

@colinmollenhour what do you think about this?

Lots of previous discussion here: #1721
Wow, I never saw any info that indicated that SHOW TABLE STATUS uses the information_schema stats cache as well so that is quite surprising but it is true, I verified it myself as well.

I think this PR should be accepted as well as #1721, but the SET statement should only be called once per session so a static variable should be added so it can be skipped on subsequent calls.

As an aside, does anyone know of a situation where turning off the information schema stats cache has a real impact on performance? Maybe it should just be recommended to disable it globally as the side effects are not well-known or documented..

I am not sure, but information_schema_stats_expiry was introduced in MySQL 8.0.3:

Would this cause problem with MySQL 5.7?

For ref, alternate solution from https://github.com/mash2/cobby-magento/blob/master/src/app/code/community/Mash2/Cobby/Helper/Resource.php

    /**
     * Find next value of autoincrement key for specified table.
     *
     * @param string $tableName
     * @throws Exception
     * @return string
     */
    public function getNextAutoincrement($tableName, $primaryKey)
    {
        $connection = Mage::getSingleton('core/resource')->getConnection('read');
        $select = $connection->select();
        $select->from($tableName, 'MAX('.$primaryKey.')');
        $result = (int)$connection->fetchOne($select) +1;
        return $result;
    }

The cobby module was original referenced in issue #1712, which it seems no longer use showTableStatus().

@colinmollenhour I added a semaphore to only set schema stats expiry to 0 once. I am happy to receive some feeedback.

I am not sure, but information_schema_stats_expiry was introduced in MySQL 8.0.3
Would this cause problem with MySQL 5.7?

Yes, I think it would.. Great observation! Seems this should be wrapped in an if clause based on server version...

I am not sure, but information_schema_stats_expiry was introduced in MySQL 8.0.3
Would this cause problem with MySQL 5.7?

Yes, I think it would.. Great observation! Seems this should be wrapped in an if clause based on server version...

but also what about mariadb or other mysql derivatives?

but also what about mariadb or other mysql derivatives?

https://dba.stackexchange.com/questions/323392/missing-information-schema-stats-expiry-in-mariadb-server-system-variables

The simple solution would be to just wrap it in a try/catch and ignore any errors. 😁

I added the try catch as @colinmollenhour proposed and followed @fballiano hint and removed the unneeed comment

I added all your suggestions into the fix, I would be interested in your opinions or other suggestions. From my point of view, this will solve a massive problem with the import/export module that damages configurable/simple relations in catalog_product_super_attribute table.