public boolean deleteAllItems(String tableName) throws DataAccessException {
ScanRequest request = new ScanRequest().withTableName(tableName);
boolean deleted = false;
ScanResult result = ddb.scan(request);
for (Map<String, AttributeValue> item : result.getItems()) {
Key key = DynamoDBUtil.getIdKey(item);
deleteItem(tableName, key);
deleted = true;
}
// keep repeating until we get through all matched items
Key lastKeyEvaluated = null;
do {
lastKeyEvaluated = result.getLastEvaluatedKey();
if (lastKeyEvaluated != null) {
request = new ScanRequest(tableName).withExclusiveStartKey(lastKeyEvaluated);
result = ddb.scan(request);
for (Map<String, AttributeValue> item : result.getItems()) {
Key key = DynamoDBUtil.getIdKey(item);
deleteItem(tableName, key);
deleted = true;
}
}
} while (lastKeyEvaluated != null);
return deleted;
}
private List<Map<String, AttributeValue>> scanInternal(
String tableName, Map<String, Condition> filter, int max, int attempt) {
LinkedList<Map<String, AttributeValue>> items = new LinkedList<Map<String, AttributeValue>>();
try {
ScanRequest request = new ScanRequest(tableName).withScanFilter(filter);
ScanResult result = ddb.scan(request);
items.addAll(result.getItems());
// keep repeating until we get through all matched items
Key lastKeyEvaluated = null;
do {
lastKeyEvaluated = result.getLastEvaluatedKey();
if (lastKeyEvaluated != null) {
request =
new ScanRequest(tableName)
.withScanFilter(filter)
.withExclusiveStartKey(lastKeyEvaluated);
result = ddb.scan(request);
items.addAll(result.getItems());
}
} while (lastKeyEvaluated != null && items.size() < max);
// truncate if needed
while (items.size() > max) {
items.removeLast();
}
return items;
} catch (AmazonServiceException e) {
if (DynamoDBUtil.AWS_ERR_CODE_RESOURCE_NOT_FOUND.equals(e.getErrorCode())) {
throw new IllegalArgumentException("no such table: " + tableName, e);
} else if (DynamoDBUtil.AWS_STATUS_CODE_SERVICE_UNAVAILABLE == e.getStatusCode()) {
// retry after a small pause
DynamoDBUtil.sleepBeforeRetry(attempt);
attempt++;
return scanInternal(tableName, filter, max, attempt);
} else {
throw new DataStoreOperationException(
"problem with table: " + tableName + ", filter: " + filter, e);
}
}
}
@Override
public int scan(
String table,
String startkey,
int recordcount,
Set<String> fields,
Vector<HashMap<String, ByteIterator>> result) {
logger.debug("scan " + recordcount + " records from key: " + startkey + " on table: " + table);
/*
* on DynamoDB's scan, startkey is *exclusive* so we need to
* getItem(startKey) and then use scan for the res
*/
GetItemRequest greq = new GetItemRequest(table, createPrimaryKey(startkey));
greq.setAttributesToGet(fields);
GetItemResult gres = null;
try {
gres = dynamoDB.getItem(greq);
} catch (AmazonServiceException ex) {
logger.error(ex.getMessage());
return SERVER_ERROR;
} catch (AmazonClientException ex) {
logger.error(ex.getMessage());
return CLIENT_ERROR;
}
if (null != gres.getItem()) {
result.add(extractResult(gres.getItem()));
}
int count = 1; // startKey is done, rest to go.
Key startKey = createPrimaryKey(startkey);
ScanRequest req = new ScanRequest(table);
req.setAttributesToGet(fields);
while (count < recordcount) {
req.setExclusiveStartKey(startKey);
req.setLimit(recordcount - count);
ScanResult res = null;
try {
res = dynamoDB.scan(req);
} catch (AmazonServiceException ex) {
logger.error(ex.getMessage());
ex.printStackTrace();
return SERVER_ERROR;
} catch (AmazonClientException ex) {
logger.error(ex.getMessage());
ex.printStackTrace();
return CLIENT_ERROR;
}
count += res.getCount();
for (Map<String, AttributeValue> items : res.getItems()) {
result.add(extractResult(items));
}
startKey = res.getLastEvaluatedKey();
}
return OK;
}
