Die vorliegende Übersetzung wurde maschinell erstellt. Im Falle eines Konflikts oder eines Widerspruchs zwischen dieser übersetzten Fassung und der englischen Fassung (einschließlich infolge von Verzögerungen bei der Übersetzung) ist die englische Fassung maßgeblich.
Das folgende C#-Codebeispiel zeigt, wie Sie mit globalen sekundären Indizes arbeiten. Das Beispiel erstellt eine Tabelle mit dem Namen Issues, die in einem einfachen Fehlerüberwachungssystem für Softwareentwicklung verwendet werden könnte. Der Partitionsschlüssel ist IssueId und der Sortierschlüssel Title. Es gibt drei globale sekundäre Indizes in dieser Tabelle:
-
CreateDateIndex– Der Partitionsschlüssel istCreateDateund der SortierschlüsselIssueId. Zusätzlich zu den Tabellenschlüsseln werden die AttributeDescriptionundStatusin den Index projiziert. -
TitleIndex– Der Partitionsschlüssel istTitleund der SortierschlüsselIssueId. Keine anderen Attribute als die Tabellenschlüssel werden in den Index projiziert. -
DueDateIndex— Der Partitionsschlüssel istDueDate. Ein Sortierschlüssel ist nicht vorhanden.) Alle Tabellenattribute werden in den Index projiziert.
Nachdem die Issues-Tabelle erstellt wurde, lädt das Programm die Tabelle mit Daten, die Software-Fehlerberichte darstellen. Anschließend werden die Daten mithilfe der globalen sekundären Indizes abgefragt. Schließlich löscht das Programm die Issues-Tabelle.
step-by-stepAnweisungen zum Testen des folgenden Beispiels finden Sie unter. .NET-Codebeispiele
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 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;
}
}
}
}
}
