Better performance on Pagination().total

[Quanr]

#281

[trancee]

@Quanr I think you are using the wrong func from SQLAlchemy. I usually import it like this:

from sqlalchemy import func

And your code change should then look like this:

    total = self.session.execute(
        self.statement.with_only_columns(
            [func.count()]
        ).order_by(None)).scalar()

Otherwise I think this pull request should be merged into the code base.

[davidism]

Closing for the same reasons discussed in the closed linked PR.