[mlthoughts2018]

You are incorrect. This is only true if you can precompute all sort orders (many types of sort orders cannot be precomputed and depend on additional context data only available at query time, especially for personalization or trending solutions). Additionally you must deal with precommitment to very poor sharding properties with Solr. With our Python approach, we could hold all results (billions of content items with trimmed down data structures representing only the thinnest container needed for each sort order representation) in memory easily, and dynamically resort on the fly or double sort by multiple sort orders that each required contextual data only available at query time.