Beispiel: Lokale sekundäre Indizes mit der Java-Dokument-API

Das folgende Java-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-stepAnweisungen zum Testen des folgenden Beispiels finden Sie unterJava-Codebeispiele.
Beispiel



package com.example.dynamodb;

import software.amazon.awssdk.core.waiters.WaiterResponse;
import software.amazon.awssdk.services.dynamodb.DynamoDbClient;
import software.amazon.awssdk.services.dynamodb.model.*;
import software.amazon.awssdk.services.dynamodb.waiters.DynamoDbWaiter;

import java.util.HashMap;
import java.util.Map;

public class DocumentAPILocalSecondaryIndexExample {

    static DynamoDbClient client = DynamoDbClient.create();
    public static String tableName = "CustomerOrders";

    public static void main(String[] args) {
        createTable();
        loadData();
        query(null);
        query("IsOpenIndex");
        query("OrderCreationDateIndex");
        deleteTable(tableName);
    }

    public static void createTable() {
        CreateTableRequest request = CreateTableRequest.builder()
            .tableName(tableName)
            .provisionedThroughput(ProvisionedThroughput.builder()
                .readCapacityUnits(1L)
                .writeCapacityUnits(1L)
                .build())
            .attributeDefinitions(
                AttributeDefinition.builder().attributeName("CustomerId").attributeType(ScalarAttributeType.S).build(),
                AttributeDefinition.builder().attributeName("OrderId").attributeType(ScalarAttributeType.N).build(),
                AttributeDefinition.builder().attributeName("OrderCreationDate").attributeType(ScalarAttributeType.N).build(),
                AttributeDefinition.builder().attributeName("IsOpen").attributeType(ScalarAttributeType.N).build())
            .keySchema(
                KeySchemaElement.builder().attributeName("CustomerId").keyType(KeyType.HASH).build(),
                KeySchemaElement.builder().attributeName("OrderId").keyType(KeyType.RANGE).build())
            .localSecondaryIndexes(
                LocalSecondaryIndex.builder()
                    .indexName("OrderCreationDateIndex")
                    .keySchema(
                        KeySchemaElement.builder().attributeName("CustomerId").keyType(KeyType.HASH).build(),
                        KeySchemaElement.builder().attributeName("OrderCreationDate").keyType(KeyType.RANGE).build())
                    .projection(Projection.builder()
                        .projectionType(ProjectionType.INCLUDE)
                        .nonKeyAttributes("ProductCategory", "ProductName")
                        .build())
                    .build(),
                LocalSecondaryIndex.builder()
                    .indexName("IsOpenIndex")
                    .keySchema(
                        KeySchemaElement.builder().attributeName("CustomerId").keyType(KeyType.HASH).build(),
                        KeySchemaElement.builder().attributeName("IsOpen").keyType(KeyType.RANGE).build())
                    .projection(Projection.builder()
                        .projectionType(ProjectionType.ALL)
                        .build())
                    .build())
            .build();

        System.out.println("Creating table " + tableName + "...");
        client.createTable(request);

        try (DynamoDbWaiter waiter = client.waiter()) {
            WaiterResponse<DescribeTableResponse> response = waiter.waitUntilTableExists(r -> r.tableName(tableName));
            response.matched().response().ifPresent(System.out::println);
        }
    }

    public static void query(String indexName) {
        System.out.println("\n***********************************************************\n");
        System.out.println("Querying table " + tableName + "...");

        if ("IsOpenIndex".equals(indexName)) {
            System.out.println("\nUsing index: '" + indexName + "': Bob's orders that are open.");
            System.out.println("Only a user-specified list of attributes are returned\n");

            Map<String, AttributeValue> values = new HashMap<>();
            values.put(":v_custid", AttributeValue.builder().s("bob@example.com").build());
            values.put(":v_isopen", AttributeValue.builder().n("1").build());

            QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .indexName(indexName)
                .keyConditionExpression("CustomerId = :v_custid and IsOpen = :v_isopen")
                .expressionAttributeValues(values)
                .projectionExpression("OrderCreationDate, ProductCategory, ProductName, OrderStatus")
                .build();

            System.out.println("Query: printing results...");
            client.query(request).items().forEach(System.out::println);

        } else if ("OrderCreationDateIndex".equals(indexName)) {
            System.out.println("\nUsing index: '" + indexName + "': Bob's orders that were placed after 01/31/2015.");
            System.out.println("Only the projected attributes are returned\n");

            Map<String, AttributeValue> values = new HashMap<>();
            values.put(":v_custid", AttributeValue.builder().s("bob@example.com").build());
            values.put(":v_orddate", AttributeValue.builder().n("20150131").build());

            QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .indexName(indexName)
                .keyConditionExpression("CustomerId = :v_custid and OrderCreationDate >= :v_orddate")
                .expressionAttributeValues(values)
                .select(Select.ALL_PROJECTED_ATTRIBUTES)
                .build();

            System.out.println("Query: printing results...");
            client.query(request).items().forEach(System.out::println);

        } else {
            System.out.println("\nNo index: All of Bob's orders, by OrderId:\n");

            Map<String, AttributeValue> values = new HashMap<>();
            values.put(":v_custid", AttributeValue.builder().s("bob@example.com").build());

            QueryRequest request = QueryRequest.builder()
                .tableName(tableName)
                .keyConditionExpression("CustomerId = :v_custid")
                .expressionAttributeValues(values)
                .build();

            System.out.println("Query: printing results...");
            client.query(request).items().forEach(System.out::println);
        }
    }

    public static void deleteTable(String tableName) {
        System.out.println("Deleting table " + tableName + "...");
        client.deleteTable(DeleteTableRequest.builder().tableName(tableName).build());

        try (DynamoDbWaiter waiter = client.waiter()) {
            waiter.waitUntilTableNotExists(r -> r.tableName(tableName));
        }
    }

    public static void loadData() {
        System.out.println("Loading data into table " + tableName + "...");

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("alice@example.com").build(),
            "OrderId", AttributeValue.builder().n("1").build(),
            "IsOpen", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150101").build(),
            "ProductCategory", AttributeValue.builder().s("Book").build(),
            "ProductName", AttributeValue.builder().s("The Great Outdoors").build(),
            "OrderStatus", AttributeValue.builder().s("PACKING ITEMS").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("alice@example.com").build(),
            "OrderId", AttributeValue.builder().n("2").build(),
            "IsOpen", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150221").build(),
            "ProductCategory", AttributeValue.builder().s("Bike").build(),
            "ProductName", AttributeValue.builder().s("Super Mountain").build(),
            "OrderStatus", AttributeValue.builder().s("ORDER RECEIVED").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("alice@example.com").build(),
            "OrderId", AttributeValue.builder().n("3").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150304").build(),
            "ProductCategory", AttributeValue.builder().s("Music").build(),
            "ProductName", AttributeValue.builder().s("A Quiet Interlude").build(),
            "OrderStatus", AttributeValue.builder().s("IN TRANSIT").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("176493").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150111").build(),
            "ProductCategory", AttributeValue.builder().s("Movie").build(),
            "ProductName", AttributeValue.builder().s("Calm Before The Storm").build(),
            "OrderStatus", AttributeValue.builder().s("SHIPPING DELAY").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("859323").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("2").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150124").build(),
            "ProductCategory", AttributeValue.builder().s("Music").build(),
            "ProductName", AttributeValue.builder().s("E-Z Listening").build(),
            "OrderStatus", AttributeValue.builder().s("DELIVERED").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("756943").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("3").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150221").build(),
            "ProductCategory", AttributeValue.builder().s("Music").build(),
            "ProductName", AttributeValue.builder().s("Symphony 9").build(),
            "OrderStatus", AttributeValue.builder().s("DELIVERED").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("645193").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("4").build(),
            "IsOpen", AttributeValue.builder().n("1").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150222").build(),
            "ProductCategory", AttributeValue.builder().s("Hardware").build(),
            "ProductName", AttributeValue.builder().s("Extra Heavy Hammer").build(),
            "OrderStatus", AttributeValue.builder().s("PACKING ITEMS").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("5").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150309").build(),
            "ProductCategory", AttributeValue.builder().s("Book").build(),
            "ProductName", AttributeValue.builder().s("How To Cook").build(),
            "OrderStatus", AttributeValue.builder().s("IN TRANSIT").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("440185").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("6").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150318").build(),
            "ProductCategory", AttributeValue.builder().s("Luggage").build(),
            "ProductName", AttributeValue.builder().s("Really Big Suitcase").build(),
            "OrderStatus", AttributeValue.builder().s("DELIVERED").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("893927").build()));

        putItem(Map.of(
            "CustomerId", AttributeValue.builder().s("bob@example.com").build(),
            "OrderId", AttributeValue.builder().n("7").build(),
            "OrderCreationDate", AttributeValue.builder().n("20150324").build(),
            "ProductCategory", AttributeValue.builder().s("Golf").build(),
            "ProductName", AttributeValue.builder().s("PGA Pro II").build(),
            "OrderStatus", AttributeValue.builder().s("OUT FOR DELIVERY").build(),
            "ShipmentTrackingId", AttributeValue.builder().s("383283").build()));
    }

    private static void putItem(Map<String, AttributeValue> item) {
        client.putItem(PutItemRequest.builder().tableName(tableName).item(item).build());
    }
}
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Lokale sekundäre Indizes: Java
Lokale sekundäre Indizes: .NET