Getting database table stats slows down stats page

[maxmilton]

Generating information about database table sizes takes a huge amount of time once there's a moderate amount of event data. Not only does this slow down the /stats page, it could also be a potential vector for DOS attacks.

See:

• https://github.com/maxmilton/trackx/blob/master/packages/trackx-api/src/routes/dash/stats.ts#L134-L273
• https://github.com/maxmilton/trackx/blob/master/packages/trackx-api/Dockerfile#L23-L29

[maxmilton]

My best guess is it's related to system resources, namely disk I/O performance.

Even so, we need to prevent it being abused and leading to DOS + it's a generally poor user experience. A first step could be splitting the data into 2 API calls; a separate one for the slow data and another for everything else.

[maxmilton]

For the time being the DB table stats are now behind a config option flag and disabled by default (#234). This is more of a workaround so I'll keep this issue open until we come up with a better solution.