Confusing pricing for Kimai. Start for free for hosted but I can't find the pricing anywhere on the website but I found a blog post about how it's no longer free. Do you pay for it and try to host it?
There are 2 problems with the analysis in the article:
1. They choose startups from 2014-2015. Valuations were (a) more reasonable then and (b) we've just been through one of the biggest bull markets of tech stocks in the past decades.
2. That taking the "Mean Valuation Growth" over that time period is meaningless if (a) there hasn't been a liquidity event and (b) if the mean is weighted by outliers (which it always is).
Portfolio / VC strategy is a bet on power laws. We, as employees, don't have that opportunity. That means we've got to be deliberate about who we join to try to hit a power law outcome.
DataFrames are just SQL. There will be no performance difference.
RDDs will be worse, so it shouldn't matter. No vectorization, no column processing, lots of serialization and de-serialization. They're basically always slower than DataFrames barring some strange use case.
Version control is the best for documentation.
But maintaining it is hard - lots of great comments here.
For anyone interested, I'm working on https://hyperlint.com/ (disclaimer: bootstrapped founder). To help automate the toil around documentation.