In the CBR codepath, the query engine uses CollectionStatistics in the CollectionInfo struct in src/mongo/db/query/query_planner_params.h. In the join codepath, the query engine uses CatalogStats in src/mongo/db/query/compiler/optimizer/join/catalog_stats.h.

Currently they cannot be merge because the join codepath does not have access to CollectionInfo, which historically was a find subsystem structure. The join codepath uses MultipleCollectionAccessor as its view of the catalog.

This ticket tracks work to consolidate these structures/files.