Transition from client side logging to server-side logging implementation

[eywalker]

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Currently DataJoint supports straightforward logging of query activities via dj.schema.log tables. However, this is entirely DJ client side logic, meaning that the logging of activity only happens for queries issued from DJ client. While this still has its uses, it cannot guarantee that it gives an accurate picture of database server activities. I propose that we migrate our logging functionality to more server side, using MySQL's built-in features such as trigger.

[dimitri-yatsenko]

Since MySQL does not provide triggers for DDL operations, the utility of server side logging will remain limited until we implement a DataJoint-specific server, which is still a bit farther in the future. So this is more of a long-term plan.

[dimitri-yatsenko]

Postgresql does provide DDL triggers, so another long-term possibility is to migrate to postgresql https://www.postgresql.org/docs/9.3/static/event-triggers.html