This deprecates forcing a return value for ArrayAgg, JSONBAgg, and
StringAgg when there are no rows in the query. Now that we have a
``default`` argument for aggregates, we want to revert to returning the
default of ``None`` which most aggregate functions return and leave it
up to the user to decide what they want to be returned by default.
The introduction of the Expression.empty_aggregate_value interface
allows the compilation stage to enable the EmptyResultSet optimization
if all the aggregates expressions implement it.
This also removes unnecessary RegrCount/Count.convert_value() methods.
Disabling the empty result set aggregation optimization when it wasn't
appropriate prevented None returned for a Count aggregation value.
Thanks Nick Pope for the review.
Thanks to Adam Johnson, Carlton Gibson, Mariusz Felisiak, and Raphael
Michel for mentoring this Google Summer of Code 2019 project and
everyone else who helped with the patch.
Special thanks to Mads Jensen, Nick Pope, and Simon Charette for
extensive reviews.
Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
This method only calls the parent method, but without the for_save
argument. The parent class, Aggregate, already ignores the for_save
argument so there is no need for special handling.
Unnecessary since its introduction in e4cf8c8420.
This wasn't possible when settings were accessed during Field initialization
time as our test suite setup script was triggering imports of expressions
before settings were configured.
David Wobrock
Nick Pope
Simon Charette
Artur Beltsov
Mariusz Felisiak
David Chorpash
John Parton
sage
Nick Pope
Jon Dufresne
Caio Ariede
Simone Pellizzari
Simon Charette
Floris den Hengst
Sergey Fedoseev
Tom
Tim Graham
chillaranand
Mads Jensen
Rustam Kashapov
Andriy Sokolovskiy