DynamoDB海量数据高效查询策略

import software.amazon.awssdk.services.dynamodb.DynamoDbClient; import software.amazon.awssdk.services.dynamodb.model.AttributeValue; import software.amazon.awssdk.services.dynamodb.model.QueryRequest; import software.amazon.awssdk.services.dynamodb.model.QueryResponse;  import java.util.ArrayList; import java.util.HashMap; import java.util.List; import java.util.Map;  public class DynamoDBLargeDataFetcher {      private final DynamoDbClient dynamoDbClient;     private final String tableName;      public DynamoDBLargeDataFetcher(DynamoDbClient dynamoDbClient, String tableName) {         this.dynamoDbClient = dynamoDbClient;         this.tableName = tableName;     }      /**      * 示例：从DynamoDB分批查询所有满足条件的乘客数据      * 注意：此方法用于演示服务器端分页，不建议直接暴露给API消费者返回海量数据。      * 适用于内部数据处理或导出场景。      *      * @param partitionKeyValue 分区键值，例如航空公司名称      * @param sortKeyCondition 排序键条件，例如预订日期范围或舱位      * @return 满足条件的所有乘客数据列表      */     public List<Map<String, AttributeValue>> fetchAllPassengers(String partitionKeyValue, String sortKeyCondition) {         List<Map<String, AttributeValue>> allItems = new ArrayList<>();         Map<String, AttributeValue> lastEvaluatedKey = null;          do {             Map<String, AttributeValue> expressionAttributeValues = new HashMap<>();             expressionAttributeValues.put(":pkVal", AttributeValue.builder().s(partitionKeyValue).build());             // 假设sortKeyCondition是一个简单的字符串匹配，实际可能更复杂             expressionAttributeValues.put(":skVal", AttributeValue.builder().s(sortKeyCondition).build());              QueryRequest.Builder requestBuilder = QueryRequest.builder()                     .tableName(tableName)                     .keyConditionExpression("airlineName = :pkVal AND bookingClass = :skVal") // 示例条件                     .expressionAttributeValues(expressionAttributeValues)                     .limit(1000); // 每次请求的数据量，可根据需求调整，但仍受1MB限制              if (lastEvaluatedKey != null) {                 requestBuilder.exclusiveStartKey(lastEvaluatedKey);             }              QueryResponse response = dynamoDbClient.query(requestBuilder.build());             allItems.addAll(response.items());             lastEvaluatedKey = response.lastEvaluatedKey();              System.out.println("Fetched " + response.items().size() + " items. Total so far: " + allItems.size());          } while (lastEvaluatedKey != null && !lastEvaluatedKey.isEmpty());          return allItems;     }      // 实际使用时，可能需要将AttributeValue映射到Java对象     // 例如使用DynamoDBMapper }