Exemple : index secondaires globaux utilisant l'API de bas niveau AWS SDK for .NET

L'exemple de code C# suivant montre comment utiliser des index secondaires globaux. L'exemple crée une table nommée Issues, utilisable dans un système simple de suivi de bogues pour le développement de logiciels. La clé de partition est IssueId, et la clé de tri Title. Il y a trois index secondaires globaux sur cette table :

CreateDateIndex – La clé de partition est CreateDate, et la clé de tri IssueId. En plus des clés de table, les attributs Description et Status sont projetés dans l'index.
TitleIndex – La clé de partition est Title, et la clé de tri IssueId. Aucun attribut autre que les clés de table n'est projeté dans l'index.
DueDateIndex – La clé de partition est DueDate et il n'y a pas de clé de tri. Tous les attributs de table sont projetés sur l'index.

Une fois la table Issues créée, le programme charge la table avec des données représentant des rapports de bogues logiciels. Il interroge ensuite les données à l'aide d'index secondaires globaux. Enfin, le programme supprime la table Issues.

Pour step-by-step obtenir des instructions sur le test de l'échantillon suivant, reportez-vous à. NETexemples de code.

Exemple


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;
                }
            }
        }
    }
}

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Conventions de rédaction

Index secondaires globaux : .NET

Index secondaires globaux : AWS CLI