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.
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
Nick Pope
Jon Dufresne
Sergey Fedoseev
Tom
Tim Graham
chillaranand
Andriy Sokolovskiy