getData returns an empty value when dataset contains a single observation

[thhomas]

getData fetch the observation matching the dimensions returned by getDimensions.
getDimensions returns the dimensions when multiple values are available.

[thhomas]

getData should use getRawDimensions instead.
And the getDimensions function should be redesigned, when argument is given getDimensions returns the desired dimension but if we need to filter the single-value dimensions, another function should be used.