Nonrelational Database ConceptsSchema FlexibilityData ModelsScalabilityHigh Availability and Fault ToleranceBASEKey-Value DatabasesData ModelData Access and Retrieval OperationsScaling Key-Value StoresAvailability in Key-Value StoresAdvantages, Trade-offs, and ConsiderationsDynamo: Key-Value DatabaseDocument DatabasesData ModelAvailability in Document StoresAdvantages, Trade-offs, and ConsiderationsMongoDB: Open Source Document DatabaseColumnar DatabasesData ModelConsistency LevelsColumnar Store ArchitectureAdvantages, Trade-offs, and ConsiderationsApache Cassandra: Open Source Columnar DatabaseGraph DatabasesData ModelData Access and RetrievalAdvantages, Trade-offs, and ConsiderationsNeo4j: Open Source Graph DatabaseConclusion