Amazon DynamoDB
开发人员指南 (API Version 2012-08-10)
AWS 服务或AWS文档中描述的功能,可能因地区/位置而异。点 击 Getting Started with Amazon AWS to see specific differences applicable to the China (Beijing) Region.

示例:使用适用于 .NET 的 AWS 开发工具包低级别 API 的全局二级索引

以下 C# 代码示例说明了如何使用全局二级索引。该示例创建了一个名为 Issues 的表,它可以在用于软件开发的简单错误跟踪系统中使用。分区键为 IssueId,排序键为 Title。此表中有三个全局二级索引:

  • CreateDateIndex – 分区键为 CreateDate,排序键为 IssueId。除表键外,还会将属性 Description 和 Status 投影到索引中。

  • TitleIndex – 分区键为 IssueId,排序键为 Title。不会将表键外的其他属性投影到索引中。

  • DueDateIndex – 分区键为 DueDate,没有排序键。所有表属性都投影到索引中。

创建 Issues 表后,程序为该表加载表示软件错误报告的数据,然后使用 全局二级索引 查询这些数据。最后,程序会删除 Issues 表。

有关测试以下示例的分步说明,请参阅.NET 代码示例

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using System; using System.Collections.Generic; using System.Linq; using Amazon.DynamoDBv2; using Amazon.DynamoDBv2.DataModel; using Amazon.DynamoDBv2.DocumentModel; using Amazon.DynamoDBv2.Model; using Amazon.Runtime; using Amazon.SecurityToken; namespace com.amazonaws.codesamples { class LowLevelGlobalSecondaryIndexExample { private static AmazonDynamoDBClient client = new AmazonDynamoDBClient(); public static String tableName = "Issues"; public static void Main(string[] args) { CreateTable(); LoadData(); QueryIndex("CreateDateIndex"); QueryIndex("TitleIndex"); QueryIndex("DueDateIndex"); DeleteTable(tableName); Console.WriteLine("To continue, press enter"); Console.Read(); } private static void CreateTable() { // Attribute definitions var attributeDefinitions = new List<AttributeDefinition>() { {new AttributeDefinition { AttributeName = "IssueId", AttributeType = "S" }}, {new AttributeDefinition { AttributeName = "Title", AttributeType = "S" }}, {new AttributeDefinition { AttributeName = "CreateDate", AttributeType = "S" }}, {new AttributeDefinition { AttributeName = "DueDate", AttributeType = "S" }} }; // Key schema for table var tableKeySchema = new List<KeySchemaElement>() { { new KeySchemaElement { AttributeName= "IssueId", KeyType = "HASH" //Partition key } }, { new KeySchemaElement { AttributeName = "Title", KeyType = "RANGE" //Sort key } } }; // Initial provisioned throughput settings for the indexes var ptIndex = new ProvisionedThroughput { ReadCapacityUnits = 1L, WriteCapacityUnits = 1L }; // CreateDateIndex var createDateIndex = new GlobalSecondaryIndex() { IndexName = "CreateDateIndex", ProvisionedThroughput = ptIndex, KeySchema = { new KeySchemaElement { AttributeName = "CreateDate", KeyType = "HASH" //Partition key }, new KeySchemaElement { AttributeName = "IssueId", KeyType = "RANGE" //Sort key } }, Projection = new Projection { ProjectionType = "INCLUDE", NonKeyAttributes = { "Description", "Status" } } }; // TitleIndex var titleIndex = new GlobalSecondaryIndex() { IndexName = "TitleIndex", ProvisionedThroughput = ptIndex, KeySchema = { new KeySchemaElement { AttributeName = "Title", KeyType = "HASH" //Partition key }, new KeySchemaElement { AttributeName = "IssueId", KeyType = "RANGE" //Sort key } }, Projection = new Projection { ProjectionType = "KEYS_ONLY" } }; // DueDateIndex var dueDateIndex = new GlobalSecondaryIndex() { IndexName = "DueDateIndex", ProvisionedThroughput = ptIndex, KeySchema = { new KeySchemaElement { AttributeName = "DueDate", KeyType = "HASH" //Partition key } }, Projection = new Projection { ProjectionType = "ALL" } }; var createTableRequest = new CreateTableRequest { TableName = tableName, ProvisionedThroughput = new ProvisionedThroughput { ReadCapacityUnits = (long)1, WriteCapacityUnits = (long)1 }, AttributeDefinitions = attributeDefinitions, KeySchema = tableKeySchema, GlobalSecondaryIndexes = { createDateIndex, titleIndex, dueDateIndex } }; Console.WriteLine("Creating table " + tableName + "..."); client.CreateTable(createTableRequest); WaitUntilTableReady(tableName); } private static void LoadData() { Console.WriteLine("Loading data into table " + tableName + "..."); // IssueId, Title, // Description, // CreateDate, LastUpdateDate, DueDate, // Priority, Status putItem("A-101", "Compilation error", "Can't compile Project X - bad version number. What does this mean?", "2013-11-01", "2013-11-02", "2013-11-10", 1, "Assigned"); putItem("A-102", "Can't read data file", "The main data file is missing, or the permissions are incorrect", "2013-11-01", "2013-11-04", "2013-11-30", 2, "In progress"); putItem("A-103", "Test failure", "Functional test of Project X produces errors", "2013-11-01", "2013-11-02", "2013-11-10", 1, "In progress"); putItem("A-104", "Compilation error", "Variable 'messageCount' was not initialized.", "2013-11-15", "2013-11-16", "2013-11-30", 3, "Assigned"); putItem("A-105", "Network issue", "Can't ping IP address 127.0.0.1. Please fix this.", "2013-11-15", "2013-11-16", "2013-11-19", 5, "Assigned"); } private static void putItem( String issueId, String title, String description, String createDate, String lastUpdateDate, String dueDate, Int32 priority, String status) { Dictionary<String, AttributeValue> item = new Dictionary<string, AttributeValue>(); item.Add("IssueId", new AttributeValue { S = issueId }); item.Add("Title", new AttributeValue { S = title }); item.Add("Description", new AttributeValue { S = description }); item.Add("CreateDate", new AttributeValue { S = createDate }); item.Add("LastUpdateDate", new AttributeValue { S = lastUpdateDate }); item.Add("DueDate", new AttributeValue { S = dueDate }); item.Add("Priority", new AttributeValue { N = priority.ToString() }); item.Add("Status", new AttributeValue { S = status }); try { client.PutItem(new PutItemRequest { TableName = tableName, Item = item }); } catch (Exception e) { Console.WriteLine(e.ToString()); } } private static void QueryIndex(string indexName) { Console.WriteLine ("\n***********************************************************\n"); Console.WriteLine("Querying index " + indexName + "..."); QueryRequest queryRequest = new QueryRequest { TableName = tableName, IndexName = indexName, ScanIndexForward = true }; String keyConditionExpression; Dictionary<string, AttributeValue> expressionAttributeValues = new Dictionary<string, AttributeValue>(); if (indexName == "CreateDateIndex") { Console.WriteLine("Issues filed on 2013-11-01\n"); keyConditionExpression = "CreateDate = :v_date and begins_with(IssueId, :v_issue)"; expressionAttributeValues.Add(":v_date", new AttributeValue { S = "2013-11-01" }); expressionAttributeValues.Add(":v_issue", new AttributeValue { S = "A-" }); } else if (indexName == "TitleIndex") { Console.WriteLine("Compilation errors\n"); keyConditionExpression = "Title = :v_title and begins_with(IssueId, :v_issue)"; expressionAttributeValues.Add(":v_title", new AttributeValue { S = "Compilation error" }); expressionAttributeValues.Add(":v_issue", new AttributeValue { S = "A-" }); // Select queryRequest.Select = "ALL_PROJECTED_ATTRIBUTES"; } else if (indexName == "DueDateIndex") { Console.WriteLine("Items that are due on 2013-11-30\n"); keyConditionExpression = "DueDate = :v_date"; expressionAttributeValues.Add(":v_date", new AttributeValue { S = "2013-11-30" }); // Select queryRequest.Select = "ALL_PROJECTED_ATTRIBUTES"; } else { Console.WriteLine("\nNo valid index name provided"); return; } queryRequest.KeyConditionExpression = keyConditionExpression; queryRequest.ExpressionAttributeValues = expressionAttributeValues; var result = client.Query(queryRequest); var items = result.Items; foreach (var currentItem in items) { foreach (string attr in currentItem.Keys) { if (attr == "Priority") { Console.WriteLine(attr + "---> " + currentItem[attr].N); } else { Console.WriteLine(attr + "---> " + currentItem[attr].S); } } Console.WriteLine(); } } private static void DeleteTable(string tableName) { Console.WriteLine("Deleting table " + tableName + "..."); client.DeleteTable(new DeleteTableRequest { TableName = tableName }); WaitForTableToBeDeleted(tableName); } private static void WaitUntilTableReady(string tableName) { string status = null; // Let us wait until table is created. Call DescribeTable. do { System.Threading.Thread.Sleep(5000); // Wait 5 seconds. try { var res = client.DescribeTable(new DescribeTableRequest { TableName = tableName }); Console.WriteLine("Table name: {0}, status: {1}", res.Table.TableName, res.Table.TableStatus); status = res.Table.TableStatus; } catch (ResourceNotFoundException) { // DescribeTable is eventually consistent. So you might // get resource not found. So we handle the potential exception. } } while (status != "ACTIVE"); } private static void WaitForTableToBeDeleted(string tableName) { bool tablePresent = true; while (tablePresent) { System.Threading.Thread.Sleep(5000); // Wait 5 seconds. try { var res = client.DescribeTable(new DescribeTableRequest { TableName = tableName }); Console.WriteLine("Table name: {0}, status: {1}", res.Table.TableName, res.Table.TableStatus); } catch (ResourceNotFoundException) { tablePresent = false; } } } } }