Connecton between simple children and parent configurables

[mbraeuner]

Environment and configuration

Akeneo Connector 100.4.10
mysql standard installation 5.6, 5.7, MariaDB <=10.2.3

Steps to reproduce

1. Setup a common product model in Akeneo
2. Add 94 variant child products with SKU length of 10 characters
3. Import models and products into Magento

Expected result

All children are connected to the configurable parent in Magento

Actual result

93 children are connected to the parent configurable product in Magento

Reason

The standard length of mysql group_concat is 1024 characters. Mysql will cut the concatenated string of child skus at char 1024.
Not all hosting providers allow to change global mysql settings

The second limitation we hit with a lot more variant products is the column type for children

Possible Solution:

• Quick fix: Set the group_concat_max_len for the current db session before executing the "Insert Into Select" query and change type text to mediumtext for the _children column
• Long term: Use a parent child relation table

[JoostWan]

This is still a issue on the latest version. First run some links are missing but second run it's added with this function

                    <item name="16" xsi:type="array">
                        <item name="method" xsi:type="string">linkSimple</item>
                        <item name="comment" xsi:type="string">Link simple products with configurable products</item>
                    </item>

But on first run with concat the SKU will be torn down and there is a wrong relation made when the torn down is exact the SKU of the parent.