In Parts 1-4, we built a transactional key-value store. It has WAL for durability, memtables and SSTables for storage, compaction to control file growth, and transactions for atomic multi-key writes. Now we move to the query layer where users can actually fire SQL queries like: CREATE TABLE payments ( amount INT , id STRING , status STRING , captured BOOL , PRIMARY KEY ( id )) INSERT INTO payments VALUES ( 500 , payment_1 , pending ,...