For D7b9, your solutions were melodic and harmonic minor scales. It's an awful lot of information for the average player to digest. To me, the guitar is extremely visual.
Assuming the change is at the 5th fret, quickly or at a jam, I'd just play an Eb major scale within the context of the change. I've been doing this for a long time. It fits well within maj or min pentatonic, depending on which pentatonic one learns first. It's a fun way to learn scales, modes and the like. It was the easiest way for me to learn all of this stuff so long ago. This method that I employ is just a quick way for a pentatonic player to get started on something new with some sort of control, and hopefully alleviate boredom. This is not easy for the average player to grasp. This system worked great for me.
A lie goes around the world before the truth gets it's shoes on. (Mark Twain)