Database Reference
In-Depth Information
this.client = client;
this.itemLimit = itemLimit;
this.totalSegments = totalSegments;
this.segment = segment;
}
@Override
void run() {
Map<String, AttributeValue> exclusiveStartKey = null;
try {
while(true) {
ScanRequest scanRequest = new ScanRequest()
.withTableName("Tbl_Book")
.withLimit(itemLimit)
.withExclusiveStartKey(exclusiveStartKey)
.withTotalSegments(totalSegments)
.withSegment(segment);
ScanResult result = client.scan(scanRequest);
//Use result.getItems()to print or process scan result
exclusiveStartKey = result.getLastEvaluatedKey();
if (exclusiveStartKey == null)
break;
}
} catch (AmazonServiceException ase) {
System.out.println(ase.getMessage());
}
}}
The second method is the abstract method (run) available in the
Runnable
interface. We
need to write the scanning-related requests inside this method. Inside this method, we con-
figure our
ScanRequest
instance with values initialized in the constructor using corres-
ponding methods. We can retrieve the output of every
ScanRequest
using the
getItems()
method available in the
ScanResult
class. Everything remains the
same. The only difference here is, instead of executing (writing) the scan request inside a
method, we are writing it inside the run method.
We will write a method (see the following code block) to call the
ParallelScanner
class. First, we will create an instance of the
java.util.concurrent.ExecutorService
class with three threads. The
