How can you avoid repeating all transformations when using both cache and persist?

The key is to perform the expensive transformation chain only once and then reuse the resulting RDD/DataFrame. First, apply all transformations and then call persist() (or cache()) on the intermediate result. Subsequent actions can then use the cached data without recomputing the entire chain. If you need to use the same data in two different contexts, you can persist it once and then reference the same persisted object in both contexts. Avoid calling cache() or persist() on the original RDD before the transformations; instead, cache the final result of the transformation pipeline. This ensures that the expensive work is done only once and both actions reuse the same cached data.