DFT without knowing the exact value of sampling rate? I have a sequence of (real) numbers that represent the magnitude of a certain natural event. I know that the samples are equispaced in time, but not the exact value of the spacings. So does that mean I do not know the sampling rate? And, how should I proceed on to doing a DFT on this dataset?

P.s. Let's say the dataset represents a historical record of the heights of high-tides on an unknown planet with one or more natural satellites. I know that the data points are equispaced, but I don't know the exact value of the spacing.
If you don’t know the sample spacing, you don’t know the sample rate.

If you know that samples are uniformly spaced, you can do a DFT and get relative frequencies. You won’t be able to map one dft bin to a specific frequency (in Hertz) unless there is some additional side info (perhaps a known reference hidden within the data).