I am using \usepackage{tikz}, \usepackage{pgfplots}, \usepgfplotslibrary{external}, \tikzexternalize. I have figures that are very slow to TeX (on the order of minutes), so I'm quite happy to have \tikzexternalize. However, whenever I reorder my figures, they are recompiled, even if the content of the figures has not changed.
Ideally, I'd like to make the figure name be some sort of hash of the content of the figure; can this be done?
I'd also be okay with a version where I had to pass an extra optional argument to \begin{tikzpicture} or some variant of it (I say "extra" because I often pass [only marks] to \begin{tikzpicture}), defining the figure name of that figure.