Add MySQL compatibility

[BlackbitDevs]

This PR provides JSON support to store activity data instead of MariaDB's dynamic columns. Whether MySQL or MariaDB shall be used can be configured in services.yml (change CustomerManagementFrameworkBundle\ActivityStore\ActivityStoreInterface to CustomerManagementFrameworkBundle\ActivityStore\MySQL).
For compatibility reasons it does not use JSON column type but keeps database structure untouched.

Solves #58

[markus-moser]

Great, thank you!

We will take a look at it in detail.

One question: if we do not change the database structure the mysql JSON search/filter possibilities will not work, correct? Wouldn't it be better to create a new/separate table for the mysql store which supports the JSON datatype?

[BlackbitDevs]

I am not sure which functionality you exactly mean. Could you point me to the code in the current master branch? Then I could look for the pendant in this PR (or say if it is missing).

[markus-moser]

This functionality is not directly used within the bundle itself but could be used for example by segment builders (or other tools) to filter the activities table based on attributes within the "attributes" column.

For example:

WHERE COLUMN_GET(attributes, 'myAttribute' AS CHAR) = 'value xyz';

The JSON datatype supports similiar functionallities:
https://dev.mysql.com/doc/refman/5.7/en/json-search-functions.html

But I think this will only work if it is actually a JSON field.

[BlackbitDevs]

Yes, with the current database structure you can use CAST(column AS JSON) (see https://dev.mysql.com/doc/refman/8.0/en/json.html#json-converting-between-types) and then you are able to filter. Of course this would not be the best solution regarding performance but we have to decide which minimum MySQL version we want to support. If 5.7 is acceptable then it certainly makes sense to use a separate datastore for MySQL.

[fashxp]

from my point of view 5.7 would be fine ... since aws aurora also supports 5.7

[CLAassistant]

All committers have signed the CLA.

[Cruiser13]

@fashxp any chance to merge this so we can use MySQL instead of MariaDB with the customer data framework?

[fashxp]

we discussed our next steps internally.
we're going to merge this PR in order to support mysql < 5.7
in addition we would like to create an additional activity store that supports the JSON data type of mysql (since now both, mysql and mariadb support this one).
see also #105

[fashxp]

@BlackbitNeueMedien are you done and have you tested the mysql store? did you also regression-test the mariadb store?

[BlackbitDevs]

Yes, we run this fork on 2 productive projects and have not noticed any problems.
But we did not compare its behaviour to the mariadb version (because we currently do not use mariadb anywhere).

[Cruiser13]

@fashxp can this be merged with the next cmf release?