https://www.enterprisedb.com/blog/postgresql-12-implementing-k-nearest-neighbor-space-partitioned-generalized-search-tree
PostgreSQL 12: Implementing K-Nearest Neighbor Space Partitioned Generalized Search Tree Indexes |...
K-nearest neighbor answers the question of "What is the closest match?". PostgreSQL 12 can answer this question, and use indexes while doing it.
k nearest neighborgeneralized search tree