We study the sample complexity of private synthetic data generation over an unbounded sized class of statistical queries, and show that any class that is privately proper PAC learnable admits a private synthetic data generator (perhaps non-efficient). Previous work on synthetic data generators focused on the case that the query class $mathcal{D}$ is finite and obtained sample complexity bounds that scale logarithmically with the size $|mathcal{D}|$. Here we construct a private synthetic data generator whose sample complexity is independent of the domain size, and we replace finiteness with the assumption that $mathcal{D}$ is privately PAC learnable (a formally weaker task, hence we obtain equivalence between the two tasks).