/// <summary>
/// Gets a fast estimation of how many documents are in the collection using metadata.
/// <para>HINT: The estimation may not be exactly accurate.</para>
/// </summary>
/// <typeparam name="T">The entity type to get the count for</typeparam>
/// <param name="cancellation">An optional cancellation token</param>
public Task <long> CountEstimatedAsync <T>(CancellationToken cancellation = default) where T : IEntity
{
return(DB.CountEstimatedAsync <T>(cancellation));
}