Dolt can grow large in disk space over many commits.

Dolt stores a copy of indexes for every commit. Foreign keys in particular generate lots of indexes. We may want a mode where we only store the indexes at the HEAD of branches and delete the history. We could expose commands to (or just automatically) regenerate indexes when a new HEAD is created (say on checkout). AS OF queries would be slow for some queries in this mode.

This could compliment partial/shallow clone #3403