/** * @param config never null */ private List<ScanRequest> createParallelScanRequestsFromExpression(Class<?> clazz, DynamoDBScanExpression scanExpression, int totalSegments, DynamoDBMapperConfig config) { if (totalSegments < 1) { throw new IllegalArgumentException("Parallel scan should have at least one scan segment."); } if (scanExpression.getExclusiveStartKey() != null) { log.info("The ExclusiveStartKey parameter specified in the DynamoDBScanExpression is ignored," + " since the individual parallel scan request on each segment is applied on a separate key scope."); } if (scanExpression.getSegment() != null || scanExpression.getTotalSegments() != null) { log.info("The Segment and TotalSegments parameters specified in the DynamoDBScanExpression are ignored."); } List<ScanRequest> parallelScanRequests= new LinkedList<ScanRequest>(); for (int segment = 0; segment < totalSegments; segment++) { ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); parallelScanRequests.add(scanRequest .withSegment(segment).withTotalSegments(totalSegments) .withExclusiveStartKey(null)); } return parallelScanRequests; }
@Override public <T> PaginatedScanList<T> scan(Class<T> clazz, DynamoDBScanExpression scanExpression, DynamoDBMapperConfig config) { config = mergeConfig(config); ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); ScanResult scanResult = db.scan(applyUserAgent(scanRequest)); return new PaginatedScanList<T>(this, clazz, db, scanRequest, scanResult, config.getPaginationLoadingStrategy(), config); }
@Override public int count(Class<?> clazz, DynamoDBScanExpression scanExpression, DynamoDBMapperConfig config) { config = mergeConfig(config); ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); scanRequest.setSelect(Select.COUNT); // Count scans can also be truncated for large datasets int count = 0; ScanResult scanResult = null; do { scanResult = db.scan(applyUserAgent(scanRequest)); count += scanResult.getCount(); scanRequest.setExclusiveStartKey(scanResult.getLastEvaluatedKey()); } while (scanResult.getLastEvaluatedKey() != null); return count; }
@Override public <T> ScanResultPage<T> scanPage(Class<T> clazz, DynamoDBScanExpression scanExpression, DynamoDBMapperConfig config) { config = mergeConfig(config); ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); ScanResult scanResult = db.scan(applyUserAgent(scanRequest)); ScanResultPage<T> result = new ScanResultPage<T>(); List<AttributeTransformer.Parameters<T>> parameters = toParameters(scanResult.getItems(), clazz, scanRequest.getTableName(), config); result.setResults(marshallIntoObjects(parameters)); result.setLastEvaluatedKey(scanResult.getLastEvaluatedKey()); result.setCount(scanResult.getCount()); result.setScannedCount(scanResult.getScannedCount()); result.setConsumedCapacity(scanResult.getConsumedCapacity()); return result; }
/** * @param config never null */ private List<ScanRequest> createParallelScanRequestsFromExpression(Class<?> clazz, DynamoDBScanExpression scanExpression, int totalSegments, DynamoDBMapperConfig config) { if (totalSegments < 1) { throw new IllegalArgumentException("Parallel scan should have at least one scan segment."); } if (scanExpression.getExclusiveStartKey() != null) { log.info("The ExclusiveStartKey parameter specified in the DynamoDBScanExpression is ignored," + " since the individual parallel scan request on each segment is applied on a separate key scope."); } if (scanExpression.getSegment() != null || scanExpression.getTotalSegments() != null) { log.info("The Segment and TotalSegments parameters specified in the DynamoDBScanExpression are ignored."); } List<ScanRequest> parallelScanRequests= new LinkedList<ScanRequest>(); for (int segment = 0; segment < totalSegments; segment++) { ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); parallelScanRequests.add(scanRequest .withSegment(segment).withTotalSegments(totalSegments) .withExclusiveStartKey(null)); } return parallelScanRequests; }
@Override public <T> PaginatedScanList<T> scan(Class<T> clazz, DynamoDBScanExpression scanExpression, DynamoDBMapperConfig config) { config = mergeConfig(config); ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); ScanResult scanResult = db.scan(applyUserAgent(scanRequest)); return new PaginatedScanList<T>(this, clazz, db, scanRequest, scanResult, config.getPaginationLoadingStrategy(), config); }
@Override public int count(Class<?> clazz, DynamoDBScanExpression scanExpression, DynamoDBMapperConfig config) { config = mergeConfig(config); ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); scanRequest.setSelect(Select.COUNT); // Count scans can also be truncated for large datasets int count = 0; ScanResult scanResult = null; do { scanResult = db.scan(applyUserAgent(scanRequest)); count += scanResult.getCount(); scanRequest.setExclusiveStartKey(scanResult.getLastEvaluatedKey()); } while (scanResult.getLastEvaluatedKey() != null); return count; }
@Override public <T> ScanResultPage<T> scanPage(Class<T> clazz, DynamoDBScanExpression scanExpression, DynamoDBMapperConfig config) { config = mergeConfig(config); ScanRequest scanRequest = createScanRequestFromExpression(clazz, scanExpression, config); ScanResult scanResult = db.scan(applyUserAgent(scanRequest)); ScanResultPage<T> result = new ScanResultPage<T>(); List<AttributeTransformer.Parameters<T>> parameters = toParameters(scanResult.getItems(), clazz, scanRequest.getTableName(), config); result.setResults(marshallIntoObjects(parameters)); result.setLastEvaluatedKey(scanResult.getLastEvaluatedKey()); result.setCount(scanResult.getCount()); result.setScannedCount(scanResult.getScannedCount()); result.setConsumedCapacity(scanResult.getConsumedCapacity()); return result; }