### how to get profile.png
1. execute a sql file, and draw its profile
python3 profile_viewer.py -f[path to sql file] -t [query title]
2. draw a given profile
python3 profile_viewer.py -qid [query_id] -t [query title]
graphviz is required(https://graphviz.org/)
on linux: apt install graphviz
on mac: brew install graphviz
### related changes
reimplement rest api: /profile/json/{query_id} to return profile in json format. currently, json profile only contains two counters: RowsReturned and TotalTime