Hi @Matt Glover,
As an employee of OpenX at the time the move to the new aggregated stats tables happened in OpenX Source 2.8, I suppose we could more technically say that non-aggregate data collection doesn't scale well using a MySQL-based relational database - and that was the key concern for the business at the time!
While other relational databases may offer scaling through sharding, OpenX at the time wasn't about to consider a move away from MySQL for it's systems, and alternatives like Cassandra, Mongo or Redis weren't considered to be mature enough - so the decision was made to go to aggregated logging.
I agree that now, it would very much be possible to use another engine other than MySQL to allow scalable, high performance logging that includes the ability to report on things like the referer, or geotargeting information, etc.
However, one of the long-standing advantages of Revive Adserver has been that you need very little technical knowledge or access to be able to install it. If MySQL or PostgreSQL is installed, and you have FTP access to a server with PHP, then that's about it. The more we add to Revive Adserver - especially in terms of adding another logging engine - the more we have to maintain. If we were going to make a change like this, I would want to make the new logging engine the default, and drop support for logging to MySQL/PostgreSQL, otherwise maintenance of logging will become a real burden.
But, how many existing Revive Adserver users would this then mean can no longer afford to run the server, because they are on really cheap hosts and can't afford a "proper" host that has root access, and wouldn't be able to manage the server anyway if they did have access?
I'm not saying "no way" - updating the logging engine would be a really fun project! But is it the right direction for the product? Do we keep things simple, and accept that it won't suit everyone - or do we make Revive Adserver more fully featured, and accept that some lower end users will end up being left behind?
Something to think about, and perhaps we'll get a survey out to the community in the near future about what direction the project needs to head in...
What version is your "Invocation Tags Plugin" - see https://matt-sparkeleven.tinytake.com/sf/NTMxMTk3XzI3NzQzMzY
If you go into the settings of this module - is asynch enabled? See: https://matt-sparkeleven.tinytake.com/sf/NTMxMTk4XzI3NzQzMzc