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);
}
}
}