Where is the database stored and how often is it compacted?

We want to run a few tests by loading hundreds of thousands of data points into the database and see how large it grows. Then alter our storage scheme (like using more integers and booleans instead of floats) and see if there is a significant difference in storage space. So:

  1. Where are the database file(s) stored on an Ubuntu 18.04 server? Do the file sizes give us a good idea of the actual data contained within the database, or are those files sparse? ([edit] It seems to be in /var/lib/influxdb/data/, but I can’t make sense of the “_series” and “autogen” directories and their numbered subdirectories.)

  2. I’ve read that the data is compacted sometime after it has been written to the database. Can I force this to happen before checking the database size? Or if not, how long should I wait for the compaction to occur after we write the data?

  3. If we try two tests, backing up to a backup file afterwards, does the size of that backup file roughly indicate the amount of space that data takes up when compressed in the InfluxDB database? Or does backing up the database somehow uncompress the data or use a different scheme for compression?

Thanks so much for your insight.