Contoh: Indeks Sekunder Global menggunakan API tingkat rendah AWS SDK for .NET

Contoh kode C# berikut menunjukkan cara menggunakan indeks sekunder global. Contoh tersebut membuat tabel bernama Issues, yang dapat digunakan dalam sistem pelacakan bug sederhana untuk pengembangan perangkat lunak. Kunci partisinya adalah IssueId dan kunci urutannya adalah Title. Ada tiga indeks sekunder global pada tabel ini:
CreateDateIndex — Kunci partisinya adalah CreateDate dan kunci urutannya adalah IssueId. Selain kunci tabel, atribut Description dan Status diproyeksikan ke dalam indeks.
TitleIndex — Kunci partisinya adalah Title dan kunci urutannya adalah IssueId. Tidak ada atribut selain kunci tabel yang diproyeksikan ke dalam indeks.
DueDateIndex — Kunci partisinya adalah DueDate, dan tidak ada kunci urutan. Semua atribut tabel diproyeksikan ke dalam indeks.
Setelah tabel Issues dibuat, program memuat tabel dengan data yang mewakili laporan bug perangkat lunak. Kemudian, data dikueri menggunakan indeks sekunder global. Terakhir, program menghapus tabel Issues.
Untuk step-by-step petunjuk pengujian sampel berikut, lihatContoh kode .NET.
contoh


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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Indeks Sekunder Global: .NET
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