We have many archiving processes and don't want to change the global parameters only if one of the archiving needs this.
Generally it is not a good practice to change some variables globally e.g. http://piwik.org/faq/troubleshooting/faq_183/
Can you explain the issue in more details? I'm not sure which mysql params you mean etc. And how would you like to set and use them?
wait_timeout. I presume that @jaceklubzinski wants to be able to set some mysql variables via core:archive param.
php-cli-options and we would do something like
$this->_connection->query("SET foobarparam = $foobarvalue"); whenever we create database connection?
Exactly what we want. Set database dynamic parameter like wait_timeout and max_allowed_packet as session parameter each time we create new database connection.
What happened here? To quote myself in an email I sent the dev team a while back:
We need to fix Matomo1 so that it sets the wait_timeout per connection. Setting the server variable is an ugly ugly hack that does not 'play well with others'. Moving from mysqli to pdo/mysql makes it even worse, since old mysqi at least allowed auto-reconnection. (Forums tell me, however, this feature has been deprecated). Further, the pdo-mysql driver does not allow (or is not documented to allow) config/connection parameters to be set via the DSN. Perhaps it is allowed, but it is not documented. The solution can be found here: https://stackoverflow.com/a/21403360/3849157 . The wait_timeout setting should either be as given above (28800) or better yet, configurable in config.ini.