Thijs

The test seems to pass now. But the other points still stand: there is something with the sorting, see the TODO in the code, and the test is slow.. This...

PR https://github.com/objectiv/objectiv-analytics/pull/1105 replaces usage of `get_bt_with_test_data()` with `get_df_with_test_data()` in conjunction with `pg_engine`. The tests still need to be migrated to actually work with BigQuery tho

Functions that can be potentially (depending on data and paramters) non-deterministic: - `fillna()` - `drop_duplicates()` - `window_row_number()` - `window_rank()` - `mode()`

> * When sorting is not specified but it's absolutely needed for useful results, we fail with an exception: window functions, `mode`, `drop_duplicates`, `fillna`, etc (akin https://github.com/objectiv/objectiv-analytics/pull/1090/files) I think we...

Although I guess failing with an error is also fine, maybe even better :thinking:. That forces the user to think about what he is doing.

One test left that has not been made to work with BigQuery yet: `tests.functional.bach.test_series_date.test_date_arithmetic`

[Relevant discussion thread](https://github.com/objectiv/objectiv-analytics/pull/792#discussion_r886657012)

doh. I duplicated this issue in #771. Closing that one, just copy pasting the description from there here so we don't lose the ideas mentioned there. #### text from 771:...

After we implement this, we should also search the code for Expressions containing `regexp_replace`, and replace those with this function.

Added small fix for test that I initially forgot in 2e208b1918caf72bca83f23ad86d60f555a9e91f. Will have a look at the review comments in a bit