Beispiel: Lokale sekundäre Indizes mit der AWS SDK for .NET-Low-Level-API

Das folgende C#-Codebeispiel zeigt, wie Sie mit lokalen sekundären Indizes in Amazon DynamoDB arbeiten. Das Beispiel erstellt eine Tabelle mit dem Namen CustomerOrders mit CustomerId als Partitionsschlüssel und OrderId als Sortierschlüssel. Es gibt zwei lokale sekundäre Indizes in dieser Tabelle:
OrderCreationDateIndex – der Sortierschlüssel ist OrderCreationDate und die folgenden Attribute werden in den Index projiziert:
- ProductCategory
- ProductName
- OrderStatus
- ShipmentTrackingId
IsOpenIndex – der Sortierschlüssel ist IsOpen und alle Tabellenattribute werden in den Index projiziert.
Nachdem die CustomerOrders-Tabelle erstellt wurde, lädt das Programm die Tabelle mit Daten, die Kundenaufträge darstellen. Mit If Then werden die Daten unter Verwendung der lokalen sekundären Indizes abgefragt. Schließlich löscht das Programm die CustomerOrders-Tabelle.
step-by-step Anweisungen zum Testen des folgenden Beispiels finden Sie unter . NETCode-Beispiele.
Beispiel


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;
                }
            }
        }
    }
}
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Lokale sekundäre Indizes: .NET
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