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

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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-step Anweisungen zum Testen des folgenden Beispiels finden Sie unter Java-Codebeispiele.

Beispiel 

package com.amazonaws.codesamples.document;

import java.util.ArrayList;
import java.util.Iterator;

import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClientBuilder;
import com.amazonaws.services.dynamodbv2.document.DynamoDB;
import com.amazonaws.services.dynamodbv2.document.Index;
import com.amazonaws.services.dynamodbv2.document.Item;
import com.amazonaws.services.dynamodbv2.document.ItemCollection;
import com.amazonaws.services.dynamodbv2.document.PutItemOutcome;
import com.amazonaws.services.dynamodbv2.document.QueryOutcome;
import com.amazonaws.services.dynamodbv2.document.Table;
import com.amazonaws.services.dynamodbv2.document.spec.QuerySpec;
import com.amazonaws.services.dynamodbv2.document.utils.ValueMap;
import com.amazonaws.services.dynamodbv2.model.AttributeDefinition;
import com.amazonaws.services.dynamodbv2.model.CreateTableRequest;
import com.amazonaws.services.dynamodbv2.model.KeySchemaElement;
import com.amazonaws.services.dynamodbv2.model.KeyType;
import com.amazonaws.services.dynamodbv2.model.LocalSecondaryIndex;
import com.amazonaws.services.dynamodbv2.model.Projection;
import com.amazonaws.services.dynamodbv2.model.ProjectionType;
import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughput;
import com.amazonaws.services.dynamodbv2.model.ReturnConsumedCapacity;
import com.amazonaws.services.dynamodbv2.model.Select;

public class DocumentAPILocalSecondaryIndexExample {

        static AmazonDynamoDB client = AmazonDynamoDBClientBuilder.standard().build();
        static DynamoDB dynamoDB = new DynamoDB(client);

        public static String tableName = "CustomerOrders";

        public static void main(String[] args) throws Exception {

                createTable();
                loadData();

                query(null);
                query("IsOpenIndex");
                query("OrderCreationDateIndex");

                deleteTable(tableName);

        }

        public static void createTable() {

                CreateTableRequest createTableRequest = new CreateTableRequest().withTableName(tableName)
                                .withProvisionedThroughput(
                                                new ProvisionedThroughput().withReadCapacityUnits((long) 1)
                                                                .withWriteCapacityUnits((long) 1));

                // Attribute definitions for table partition and sort keys
                ArrayList<AttributeDefinition> attributeDefinitions = new ArrayList<AttributeDefinition>();
                attributeDefinitions
                                .add(new AttributeDefinition().withAttributeName("CustomerId").withAttributeType("S"));
                attributeDefinitions.add(new AttributeDefinition().withAttributeName("OrderId").withAttributeType("N"));

                // Attribute definition for index primary key attributes
                attributeDefinitions
                                .add(new AttributeDefinition().withAttributeName("OrderCreationDate")
                                                .withAttributeType("N"));
                attributeDefinitions.add(new AttributeDefinition().withAttributeName("IsOpen").withAttributeType("N"));

                createTableRequest.setAttributeDefinitions(attributeDefinitions);

                // Key schema for table
                ArrayList<KeySchemaElement> tableKeySchema = new ArrayList<KeySchemaElement>();
                tableKeySchema.add(new KeySchemaElement().withAttributeName("CustomerId").withKeyType(KeyType.HASH)); // Partition
                                                                                                                      // key
                tableKeySchema.add(new KeySchemaElement().withAttributeName("OrderId").withKeyType(KeyType.RANGE)); // Sort
                                                                                                                    // key

                createTableRequest.setKeySchema(tableKeySchema);

                ArrayList<LocalSecondaryIndex> localSecondaryIndexes = new ArrayList<LocalSecondaryIndex>();

                // OrderCreationDateIndex
                LocalSecondaryIndex orderCreationDateIndex = new LocalSecondaryIndex()
                                .withIndexName("OrderCreationDateIndex");

                // Key schema for OrderCreationDateIndex
                ArrayList<KeySchemaElement> indexKeySchema = new ArrayList<KeySchemaElement>();
                indexKeySchema.add(new KeySchemaElement().withAttributeName("CustomerId").withKeyType(KeyType.HASH)); // Partition
                                                                                                                      // key
                indexKeySchema.add(new KeySchemaElement().withAttributeName("OrderCreationDate")
                                .withKeyType(KeyType.RANGE)); // Sort
                                                              // key

                orderCreationDateIndex.setKeySchema(indexKeySchema);

                // Projection (with list of projected attributes) for
                // OrderCreationDateIndex
                Projection projection = new Projection().withProjectionType(ProjectionType.INCLUDE);
                ArrayList<String> nonKeyAttributes = new ArrayList<String>();
                nonKeyAttributes.add("ProductCategory");
                nonKeyAttributes.add("ProductName");
                projection.setNonKeyAttributes(nonKeyAttributes);

                orderCreationDateIndex.setProjection(projection);

                localSecondaryIndexes.add(orderCreationDateIndex);

                // IsOpenIndex
                LocalSecondaryIndex isOpenIndex = new LocalSecondaryIndex().withIndexName("IsOpenIndex");

                // Key schema for IsOpenIndex
                indexKeySchema = new ArrayList<KeySchemaElement>();
                indexKeySchema.add(new KeySchemaElement().withAttributeName("CustomerId").withKeyType(KeyType.HASH)); // Partition
                                                                                                                      // key
                indexKeySchema.add(new KeySchemaElement().withAttributeName("IsOpen").withKeyType(KeyType.RANGE)); // Sort
                                                                                                                   // key

                // Projection (all attributes) for IsOpenIndex
                projection = new Projection().withProjectionType(ProjectionType.ALL);

                isOpenIndex.setKeySchema(indexKeySchema);
                isOpenIndex.setProjection(projection);

                localSecondaryIndexes.add(isOpenIndex);

                // Add index definitions to CreateTable request
                createTableRequest.setLocalSecondaryIndexes(localSecondaryIndexes);

                System.out.println("Creating table " + tableName + "...");
                System.out.println(dynamoDB.createTable(createTableRequest));

                // Wait for table to become active
                System.out.println("Waiting for " + tableName + " to become ACTIVE...");
                try {
                        Table table = dynamoDB.getTable(tableName);
                        table.waitForActive();
                } catch (InterruptedException e) {
                        e.printStackTrace();
                }
        }

        public static void query(String indexName) {

                Table table = dynamoDB.getTable(tableName);

                System.out.println("\n***********************************************************\n");
                System.out.println("Querying table " + tableName + "...");

                QuerySpec querySpec = new QuerySpec().withConsistentRead(true).withScanIndexForward(true)
                                .withReturnConsumedCapacity(ReturnConsumedCapacity.TOTAL);

                if (indexName == "IsOpenIndex") {

                        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");
                        Index index = table.getIndex(indexName);

                        querySpec.withKeyConditionExpression("CustomerId = :v_custid and IsOpen = :v_isopen")
                                        .withValueMap(new ValueMap().withString(":v_custid", "bob@example.com")
                                                        .withNumber(":v_isopen", 1));

                        querySpec.withProjectionExpression(
                                        "OrderCreationDate, ProductCategory, ProductName, OrderStatus");

                        ItemCollection<QueryOutcome> items = index.query(querySpec);
                        Iterator<Item> iterator = items.iterator();

                        System.out.println("Query: printing results...");

                        while (iterator.hasNext()) {
                                System.out.println(iterator.next().toJSONPretty());
                        }

                } else if (indexName == "OrderCreationDateIndex") {
                        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");
                        Index index = table.getIndex(indexName);

                        querySpec.withKeyConditionExpression(
                                        "CustomerId = :v_custid and OrderCreationDate >= :v_orddate")
                                        .withValueMap(
                                                        new ValueMap().withString(":v_custid", "bob@example.com")
                                                                        .withNumber(":v_orddate",
                                                                                        20150131));

                        querySpec.withSelect(Select.ALL_PROJECTED_ATTRIBUTES);

                        ItemCollection<QueryOutcome> items = index.query(querySpec);
                        Iterator<Item> iterator = items.iterator();

                        System.out.println("Query: printing results...");

                        while (iterator.hasNext()) {
                                System.out.println(iterator.next().toJSONPretty());
                        }

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

                        querySpec.withKeyConditionExpression("CustomerId = :v_custid")
                                        .withValueMap(new ValueMap().withString(":v_custid", "bob@example.com"));

                        ItemCollection<QueryOutcome> items = table.query(querySpec);
                        Iterator<Item> iterator = items.iterator();

                        System.out.println("Query: printing results...");

                        while (iterator.hasNext()) {
                                System.out.println(iterator.next().toJSONPretty());
                        }

                }

        }

        public static void deleteTable(String tableName) {

                Table table = dynamoDB.getTable(tableName);
                System.out.println("Deleting table " + tableName + "...");
                table.delete();

                // Wait for table to be deleted
                System.out.println("Waiting for " + tableName + " to be deleted...");
                try {
                        table.waitForDelete();
                } catch (InterruptedException e) {
                        e.printStackTrace();
                }
        }

        public static void loadData() {

                Table table = dynamoDB.getTable(tableName);

                System.out.println("Loading data into table " + tableName + "...");

                Item item = new Item().withPrimaryKey("CustomerId", "alice@example.com").withNumber("OrderId", 1)
                                .withNumber("IsOpen", 1).withNumber("OrderCreationDate", 20150101)
                                .withString("ProductCategory", "Book")
                                .withString("ProductName", "The Great Outdoors")
                                .withString("OrderStatus", "PACKING ITEMS");
                // no ShipmentTrackingId attribute

                PutItemOutcome putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "alice@example.com").withNumber("OrderId", 2)
                                .withNumber("IsOpen", 1).withNumber("OrderCreationDate", 20150221)
                                .withString("ProductCategory", "Bike")
                                .withString("ProductName", "Super Mountain")
                                .withString("OrderStatus", "ORDER RECEIVED");
                // no ShipmentTrackingId attribute

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "alice@example.com").withNumber("OrderId", 3)
                                // no IsOpen attribute
                                .withNumber("OrderCreationDate", 20150304).withString("ProductCategory", "Music")
                                .withString("ProductName", "A Quiet Interlude").withString("OrderStatus", "IN TRANSIT")
                                .withString("ShipmentTrackingId", "176493");

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 1)
                                // no IsOpen attribute
                                .withNumber("OrderCreationDate", 20150111).withString("ProductCategory", "Movie")
                                .withString("ProductName", "Calm Before The Storm")
                                .withString("OrderStatus", "SHIPPING DELAY")
                                .withString("ShipmentTrackingId", "859323");

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 2)
                                // no IsOpen attribute
                                .withNumber("OrderCreationDate", 20150124).withString("ProductCategory", "Music")
                                .withString("ProductName", "E-Z Listening").withString("OrderStatus", "DELIVERED")
                                .withString("ShipmentTrackingId", "756943");

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 3)
                                // no IsOpen attribute
                                .withNumber("OrderCreationDate", 20150221).withString("ProductCategory", "Music")
                                .withString("ProductName", "Symphony 9").withString("OrderStatus", "DELIVERED")
                                .withString("ShipmentTrackingId", "645193");

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 4)
                                .withNumber("IsOpen", 1).withNumber("OrderCreationDate", 20150222)
                                .withString("ProductCategory", "Hardware")
                                .withString("ProductName", "Extra Heavy Hammer")
                                .withString("OrderStatus", "PACKING ITEMS");
                // no ShipmentTrackingId attribute

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 5)
                                /* no IsOpen attribute */
                                .withNumber("OrderCreationDate", 20150309).withString("ProductCategory", "Book")
                                .withString("ProductName", "How To Cook").withString("OrderStatus", "IN TRANSIT")
                                .withString("ShipmentTrackingId", "440185");

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 6)
                                // no IsOpen attribute
                                .withNumber("OrderCreationDate", 20150318).withString("ProductCategory", "Luggage")
                                .withString("ProductName", "Really Big Suitcase").withString("OrderStatus", "DELIVERED")
                                .withString("ShipmentTrackingId", "893927");

                putItemOutcome = table.putItem(item);

                item = new Item().withPrimaryKey("CustomerId", "bob@example.com").withNumber("OrderId", 7)
                                /* no IsOpen attribute */
                                .withNumber("OrderCreationDate", 20150324).withString("ProductCategory", "Golf")
                                .withString("ProductName", "PGA Pro II").withString("OrderStatus", "OUT FOR DELIVERY")
                                .withString("ShipmentTrackingId", "383283");

                putItemOutcome = table.putItem(item);
                assert putItemOutcome != null;
        }

}