Design Discusssions Indices and Query Plans

https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentSkipListMap.html

https://github.com/eugenp/tutorials/blob/master/core-java-modules/core-java-concurrency-collections/src/main/java/com/baeldung/concurrent/skiplist/EventWindowSort.java