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Simon Charette 9f3cce172f Refs #26430 -- Re-introduced empty aggregation optimization.
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.
2021-07-02 07:25:42 +02:00
..
2020-06-03 11:42:42 +02:00
2021-04-30 14:04:22 +02:00

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