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.
Question
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.
Solution
首先，我们需要逐一分析每个选项的正确性。
a. Dynamo doesn’t require a rigid schema before inserting data. DynamoDB 是一种 NoSQL 数据库，它不需要在插入数据之前定义一个固定的模式（schema）。因此，这个选项是正确的。
b. MongoDB supports the concepts of primary key and foreign key. MongoDB 是一种 NoSQL 数据库，它确实支持主键（primary key）的概念，但它不直接支持外键（foreign key）。因此，这个选项是不正确的。
c. Google's Bigtable does not support schema. Google's Bigtable 是一种分布式存储系统，它不需要预定义的模式（schema），数据是以键值对的形式存储的。因此，这个选项是正确的。
d. The concept of schema in MongoDB is flexible, which allows programmers to modify data structure at runtime. MongoDB 的模式（schema）是灵活的，允许程序员在运行时修改数据结构。因此，这个选项是正确的。
综上所述，正确的选项是： a. Dynamo doesn’t require a rigid schema before inserting data. 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.
Similar Questions
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