Question

我正在使用elephantbird项目将json文件加载到pig。但我不知道如何在加载时定义模式。没有找到相同的描述。

数据：

{"id":22522,"name":"Product1","colors":["Red","Blue"],"sizes":["S","M"]}
{"id":22523,"name":"Product2","colors":["White","Blue"],"sizes":["M"]}

代码：

feed = LOAD '$INPUT' USING com.twitter.elephantbird.pig.load.JsonLoader() AS products_json;

extracted_products = FOREACH feed GENERATE
    products_json#'id' AS id,
    products_json#'name' AS name,
    products_json#'colors' AS colors,
    products_json#'sizes' AS sizes;

describe extracted_products;

结果：

extracted_products: {id: chararray,name: bytearray,colors: bytearray,sizes: bytearray}

我如何为它们提供正确的架构（int，string，array，array）以及如何将数组元素展平为行？

提前致谢

Answer 1

将json数组转换为元组：

feed = LOAD '$INPUT' USING com.twitter.elephantbird.pig.load.JsonLoader() AS products_json;

extracted_products = FOREACH feed GENERATE
products_json#'id' AS id:chararray,
products_json#'name' AS name:chararray,
products_json#'colors' AS colors:{t:(i:chararray)},
products_json#'sizes' AS sizes:{t:(i:chararray)};

压扁一个元组

flattened = foreach extracted_products generate id,flatten(colors);

我如何使用jsonloader定义数组的模式？

1 个答案: