Which of the following is/are correct?试题 4选择一项或多项：a.Google's Bigtable cannot manage versioned data. b.Dynamo uses consistent hashing to achieve incremental scalability.c.In Google's Bigtable, the row range for a (big) table is dynamically partitioned according to the lexicographic order of row keys.  d.Google's Bigtable cannot be used with MapReduce for running large-scale parallel computations.

Which of the following is/are correct for Google's Bigtable solution?试题 2选择一项或多项：a.Google's Bigtable uses the shared-nothing architecture in which the nodes share memory but do not share disk.b.Google's Bigtable dynamically partitions a (big) table into tablets based on column keys.c.Google's Bigtable uses supercomputers to scale out.d.Google's Bigtable supports transactions across row keys. e.In a (big)table, each value is uniquely determined by a row key, column key, and a timestamp.

Dynamo is a NoSQL database developed by Amazon. Which of the following about Dynamo is/are correct?试题 8选择一项或多项：a.Dynamo is targeted mainly at applications where no updates are rejected due to concurrent writes.b.Dynamo uses the technique of consistent hashing to map each node to a single datacenter.c.Dynamo is designed to achieve strong consistency and high data availability simultaneously.d.Dynamo provides security related support for managing data, such as authentication and authorization.

Which of the following is/are correct?试题 6选择一项或多项：a.Dynamo doesn’t require a rigid schema before inserting data.b.MongoDB supports the concepts of primary key and foreign key.c.Google's Bigtable does not support schema.d.The concept of schema in MongoDB is flexible, which allows programmers to modify data structure at runtime.

Which of the following is/are correct?试题 13选择一项或多项：a.Relational databases often cannot scale beyond certain point under ACID constraints.b.Scale up means to add more nodes to a system, e.g. adding more web servers.c.NoSQL databases often consider to scale out by using commodity hardware and free software.d.All NoSQL databases are scalable.

Which of the following is/are correct for Google's Bigtable solution?Question 12Select one or more:Select one or more:a.In a (big)table, columns are grouped into column families, and columns within a column family are pre-defined by the schema of the (big)table.b.Tablets are the basic units of access control.c.Columns are the basic units of distribution and load balancing.d.Column families within a (big) table can be dynamically created (i.e., no need to predefine a column family before data is stored under any column key in that family).e.The choice of row-keys affects partitioning of rows into tablets.