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Il seguente esempio di codice Java mostra come utilizzare gli indici secondari globali in Amazon DynamoDB. Nell'esempio viene creata una tabella denominata CustomerOrders con una chiave di partizione CustomerId e una chiave di ordinamento OrderId. In questa tabella esistono due indici secondari locali:
-
OrderCreationDateIndex: la chiave di ordinamento èOrderCreationDatee i seguenti attributi sono proiettati sull'indice.ProductCategoryProductNameOrderStatusShipmentTrackingId
-
IsOpenIndex: la chiave di ordinamento èIsOpene tutti gli attributi della tabella vengono proiettati nell'indice.
Una volta creata la tabella CustomerOrders, il programma carica la tabella con i dati che rappresentano gli ordini dei clienti. Quindi esegue una query sui dati utilizzando gli indici secondari locali. Infine, il programma elimina la tabella CustomerOrders.
Per step-by-step istruzioni su come testare il seguente esempio, vedereEsempi di codice Java.
Esempio
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;
}
}
