c++ - 如何在C++中对DynamoDB GetItem()启用ConsistentRead

Question

根据Aws SDK documentation，默认情况下，GetItem()提供最终一致的读取。如何将ConsistentRead设置为true以在代码中启用强一致性读取？

template<typename T>
bool DynamoDBClient::GetItemByKey(const std::string& table, const std::string& key_name, const std::string& key_value, const std::string& projection_expr, T& result) {
  Aws::SDKOptions options;
  options.loggingOptions.logLevel = Aws::Utils::Logging::LogLevel::Info;
  AWS::InitAPI(options);

  // Set up request.
  Aws::DynamoDB::Model::GetItemRequest gir;
  gir.SetTableName(String2AwsString(table));
  Aws::DynamoDB::Model::AttributeValue hashKey;
  hashKey.setS(String2AwsString(key_value));
  gir.AddKey(String2AwsString(key_name), hashKey);
  if (!projection_expr.empty()) {
    gir.SetProjectionExpression(projection_expr);
  }

  // Retrieve item from table.
  const Aws::DynamoDB::Model::GetItemOutcome& result = dynamodb_client_->GetItem(gir);
  ...
}

Answer 1

如Oliver所指出的，可以通过GetItemRequest::SetConsistentRead()或GetItemRequestWithConsistentRead()方法启用/禁用 ConsistentRead 标志，如下所示:

// Set up request.
Aws::DynamoDB::Model::GetItemRequest gir;
gir.SetTableName(String2AwsString(table));
gir.SetConsistentRead(true);