Dynamodb 简明教程
DynamoDB - Data Types
DynamoDB 支持的数据类型包括特定于属性、操作和您选择的编码语言的数据类型。
Data types supported by DynamoDB include those specific to attributes, actions, and your coding language of choice.
Attribute Data Types
DynamoDB 支持大量表属性数据类型。每种数据类型都属于以下三个类别之一 −
DynamoDB supports a large set of data types for table attributes. Each data type falls into one of the three following categories −
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Scalar − These types represent a single value, and include number, string, binary, Boolean, and null.
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Document − These types represent a complex structure possessing nested attributes, and include lists and maps.
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Set − These types represent multiple scalars, and include string sets, number sets, and binary sets.
记住 DynamoDB 是无模式、无 SQL 数据库，创建表时不需要属性或数据类型定义。它仅需要主键属性数据类型，而关系数据库管理系统 (RDBMS) 在创建表时则需要列数据类型。
Remember DynamoDB as a schemaless, NoSQL database that does not need attribute or data type definitions when creating a table. It only requires a primary key attribute data types in contrast to RDBMS, which require column data types on table creation.
Scalars
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Numbers − They are limited to 38 digits, and are either positive, negative, or zero.
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String − They are Unicode using UTF-8, with a minimum length of >0 and maximum of 400KB.
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Binary − They store any binary data, e.g., encrypted data, images, and compressed text. DynamoDB views its bytes as unsigned.
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Boolean − They store true or false.
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Null − They represent an unknown or undefined state.
Document
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List − It stores ordered value collections, and uses square ([…]) brackets.
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Map − It stores unordered name-value pair collections, and uses curly ({…}) braces.
Set
无论是否为数字、字符串或二进制，集合必须包含相同类型的值。针对集合设置的唯一限制涉及 400KB 项目大小限制，并且每个元素必须唯一。
Sets must contain elements of the same type whether number, string, or binary. The only limits placed on sets consist of the 400KB item size limit, and each element being unique.
Action Data Types
DynamoDB API 保存由操作使用的各种数据类型。你可以查看以下一些关键类型 -
DynamoDB API holds various data types used by actions. You can review a selection of the following key types −
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AttributeDefinition − It represents key table and index schema.
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Capacity − It represents the quantity of throughput consumed by a table or index.
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CreateGlobalSecondaryIndexAction − It represents a new global secondary index added to a table.
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LocalSecondaryIndex − It represents local secondary index properties.
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ProvisionedThroughput − It represents the provisioned throughput for an index or table.
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PutRequest − It represents PutItem requests.
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TableDescription − It represents table properties.