示例：使用 AWS SDK for .NET 低级 API 的本地二级索引 - Amazon DynamoDB

示例：使用 AWS SDK for .NET 低级 API 的本地二级索引

以下 C# 代码示例显示如何在 Amazon DynamoDB 中处理本地二级索引。示例创建名为 CustomerOrders 的表，其分区键为 CustomerId，排序键为 OrderId。此表上有两个本地二级索引：

  • OrderCreationDateIndex — 排序键是 OrderCreationDate，并将以下属性投影到索引：

    • ProductCategory

    • ProductName

    • OrderStatus

    • ShipmentTrackingId

  • IsOpenIndex — 排序键是 IsOpen，并将表的所有属性投影到索引。

创建 CustomerOrders 表后，程序为该表加载表示客户订单的数据。然后使用本地二级索引查询这些数据。最后，程序会删除 CustomerOrders 表。

有关测试以下示例的分步说明，请参阅 .NET 代码示例。

例 
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 LowLevelLocalSecondaryIndexExample
    {
        private static AmazonDynamoDBClient client = new AmazonDynamoDBClient();
        private static string tableName = "CustomerOrders";

        static void Main(string[] args)
        {
            try
            {
                CreateTable();
                LoadData();

                Query(null);
                Query("IsOpenIndex");
                Query("OrderCreationDateIndex");

                DeleteTable(tableName);

                Console.WriteLine("To continue, press Enter");
                Console.ReadLine();
            }
            catch (AmazonDynamoDBException e) { Console.WriteLine(e.Message); }
            catch (AmazonServiceException e) { Console.WriteLine(e.Message); }
            catch (Exception e) { Console.WriteLine(e.Message); }
        }

        private static void CreateTable()
        {
            var createTableRequest =
                new CreateTableRequest()
                {
                    TableName = tableName,
                    ProvisionedThroughput =
                    new ProvisionedThroughput()
                    {
                        ReadCapacityUnits = (long)1,
                        WriteCapacityUnits = (long)1
                    }
                };

            var attributeDefinitions = new List<AttributeDefinition>()
        {
            // Attribute definitions for table primary key
            { new AttributeDefinition() {
                  AttributeName = "CustomerId", AttributeType = "S"
              } },
            { new AttributeDefinition() {
                  AttributeName = "OrderId", AttributeType = "N"
              } },
            // Attribute definitions for index primary key
            { new AttributeDefinition() {
                  AttributeName = "OrderCreationDate", AttributeType = "N"
              } },
            { new AttributeDefinition() {
                  AttributeName = "IsOpen", AttributeType = "N"
              }}
        };

            createTableRequest.AttributeDefinitions = attributeDefinitions;

            // Key schema for table
            var tableKeySchema = new List<KeySchemaElement>()
        {
            { new KeySchemaElement() {
                  AttributeName = "CustomerId", KeyType = "HASH"
              } },                                                  //Partition key
            { new KeySchemaElement() {
                  AttributeName = "OrderId", KeyType = "RANGE"
              } }                                                //Sort key
        };

            createTableRequest.KeySchema = tableKeySchema;

            var localSecondaryIndexes = new List<LocalSecondaryIndex>();

            // OrderCreationDateIndex
            LocalSecondaryIndex orderCreationDateIndex = new LocalSecondaryIndex()
            {
                IndexName = "OrderCreationDateIndex"
            };

            // Key schema for OrderCreationDateIndex
            var indexKeySchema = new List<KeySchemaElement>()
        {
            { new KeySchemaElement() {
                  AttributeName = "CustomerId", KeyType = "HASH"
              } },                                                    //Partition key
            { new KeySchemaElement() {
                  AttributeName = "OrderCreationDate", KeyType = "RANGE"
              } }                                                            //Sort key
        };

            orderCreationDateIndex.KeySchema = indexKeySchema;

            // Projection (with list of projected attributes) for
            // OrderCreationDateIndex
            var projection = new Projection()
            {
                ProjectionType = "INCLUDE"
            };

            var nonKeyAttributes = new List<string>()
        {
            "ProductCategory",
            "ProductName"
        };
            projection.NonKeyAttributes = nonKeyAttributes;

            orderCreationDateIndex.Projection = projection;

            localSecondaryIndexes.Add(orderCreationDateIndex);

            // IsOpenIndex
            LocalSecondaryIndex isOpenIndex
                = new LocalSecondaryIndex()
                {
                    IndexName = "IsOpenIndex"
                };

            // Key schema for IsOpenIndex
            indexKeySchema = new List<KeySchemaElement>()
        {
            { new KeySchemaElement() {
                  AttributeName = "CustomerId", KeyType = "HASH"
              }},                                                     //Partition key
            { new KeySchemaElement() {
                  AttributeName = "IsOpen", KeyType = "RANGE"
              }}                                                  //Sort key
        };

            // Projection (all attributes) for IsOpenIndex
            projection = new Projection()
            {
                ProjectionType = "ALL"
            };

            isOpenIndex.KeySchema = indexKeySchema;
            isOpenIndex.Projection = projection;

            localSecondaryIndexes.Add(isOpenIndex);

            // Add index definitions to CreateTable request
            createTableRequest.LocalSecondaryIndexes = localSecondaryIndexes;

            Console.WriteLine("Creating table " + tableName + "...");
            client.CreateTable(createTableRequest);
            WaitUntilTableReady(tableName);
        }

        public static void Query(string indexName)
        {
            Console.WriteLine("\n***********************************************************\n");
            Console.WriteLine("Querying table " + tableName + "...");

            QueryRequest queryRequest = new QueryRequest()
            {
                TableName = tableName,
                ConsistentRead = true,
                ScanIndexForward = true,
                ReturnConsumedCapacity = "TOTAL"
            };


            String keyConditionExpression = "CustomerId = :v_customerId";
            Dictionary<string, AttributeValue> expressionAttributeValues = new Dictionary<string, AttributeValue> {
            {":v_customerId", new AttributeValue {
                 S = "bob@example.com"
             }}
        };


            if (indexName == "IsOpenIndex")
            {
                Console.WriteLine("\nUsing index: '" + indexName
                          + "': Bob's orders that are open.");
                Console.WriteLine("Only a user-specified list of attributes are returned\n");
                queryRequest.IndexName = indexName;

                keyConditionExpression += " and IsOpen = :v_isOpen";
                expressionAttributeValues.Add(":v_isOpen", new AttributeValue
                {
                    N = "1"
                });

                // ProjectionExpression
                queryRequest.ProjectionExpression = "OrderCreationDate, ProductCategory, ProductName, OrderStatus";
            }
            else if (indexName == "OrderCreationDateIndex")
            {
                Console.WriteLine("\nUsing index: '" + indexName
                          + "': Bob's orders that were placed after 01/31/2013.");
                Console.WriteLine("Only the projected attributes are returned\n");
                queryRequest.IndexName = indexName;

                keyConditionExpression += " and OrderCreationDate > :v_Date";
                expressionAttributeValues.Add(":v_Date", new AttributeValue
                {
                    N = "20130131"
                });

                // Select
                queryRequest.Select = "ALL_PROJECTED_ATTRIBUTES";
            }
            else
            {
                Console.WriteLine("\nNo index: All of Bob's orders, by OrderId:\n");
            }
            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 == "OrderId" || attr == "IsOpen"
                        || attr == "OrderCreationDate")
                    {
                        Console.WriteLine(attr + "---> " + currentItem[attr].N);
                    }
                    else
                    {
                        Console.WriteLine(attr + "---> " + currentItem[attr].S);
                    }
                }
                Console.WriteLine();
            }
            Console.WriteLine("\nConsumed capacity: " + result.ConsumedCapacity.CapacityUnits + "\n");
        }

        private static void DeleteTable(string tableName)
        {
            Console.WriteLine("Deleting table " + tableName + "...");
            client.DeleteTable(new DeleteTableRequest()
            {
                TableName = tableName
            });
            WaitForTableToBeDeleted(tableName);
        }

        public static void LoadData()
        {
            Console.WriteLine("Loading data into table " + tableName + "...");

            Dictionary<string, AttributeValue> item = new Dictionary<string, AttributeValue>();

            item["CustomerId"] = new AttributeValue
            {
                S = "alice@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "1"
            };
            item["IsOpen"] = new AttributeValue
            {
                N = "1"
            };
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130101"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Book"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "The Great Outdoors"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "PACKING ITEMS"
            };
            /* no ShipmentTrackingId attribute */
            PutItemRequest putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "alice@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "2"
            };
            item["IsOpen"] = new AttributeValue
            {
                N = "1"
            };
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130221"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Bike"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "Super Mountain"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "ORDER RECEIVED"
            };
            /* no ShipmentTrackingId attribute */
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "alice@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "3"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130304"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Music"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "A Quiet Interlude"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "IN TRANSIT"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "176493"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "1"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130111"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Movie"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "Calm Before The Storm"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "SHIPPING DELAY"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "859323"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "2"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130124"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Music"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "E-Z Listening"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "DELIVERED"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "756943"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "3"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130221"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Music"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "Symphony 9"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "DELIVERED"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "645193"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "4"
            };
            item["IsOpen"] = new AttributeValue
            {
                N = "1"
            };
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130222"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Hardware"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "Extra Heavy Hammer"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "PACKING ITEMS"
            };
            /* no ShipmentTrackingId attribute */
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "5"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130309"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Book"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "How To Cook"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "IN TRANSIT"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "440185"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "6"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130318"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Luggage"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "Really Big Suitcase"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "DELIVERED"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "893927"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);

            item = new Dictionary<string, AttributeValue>();
            item["CustomerId"] = new AttributeValue
            {
                S = "bob@example.com"
            };
            item["OrderId"] = new AttributeValue
            {
                N = "7"
            };
            /* no IsOpen attribute */
            item["OrderCreationDate"] = new AttributeValue
            {
                N = "20130324"
            };
            item["ProductCategory"] = new AttributeValue
            {
                S = "Golf"
            };
            item["ProductName"] = new AttributeValue
            {
                S = "PGA Pro II"
            };
            item["OrderStatus"] = new AttributeValue
            {
                S = "OUT FOR DELIVERY"
            };
            item["ShipmentTrackingId"] = new AttributeValue
            {
                S = "383283"
            };
            putItemRequest = new PutItemRequest
            {
                TableName = tableName,
                Item = item,
                ReturnItemCollectionMetrics = "SIZE"
            };
            client.PutItem(putItemRequest);
        }

        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;
                }
            }
        }
    }
}