Original report from Paula:
For CovarianceIndex we have min/max/mean fields defined as Float in the DB column, while the values will be of complex type. This fails with Postgres.
Lia's followup comment"
Good catch with the PostgreSQL.
Looking at the code, I think that more DTs potentially will have this problems (all with a dtype=complex and *Index inheriting from DataTypeMatrix): Fourier, Wavelet, ComplexCoherenceSpectrum and the Covariance that you mention.