A common reason is using a partition key with excessive cardinality. On creating a table, users can optionally specify a column as a partition key by which data will be separated. A new file system directory will be created for every key value. This is typically a data management technique, allowing users to cleanly separate data logically in a table. Operations such as DROP PARTITION subsequently allow fast deletion of data subsets. This powerful feature can, however, easily be misused, with users interpreting it as a simple optimization technique for queries.
Гуменник назвал текущий сезон прорывным для себя19:20
。业内人士推荐新收录的资料作为进阶阅读
В России начнут строже наказывать за нарушение правил пересечения границы20:12
Фото: DimaBerlin / Shutterstock / Fotodom
。关于这个话题，PDF资料提供了深入分析
Что думаешь? Оцени!
上周的原油市场，就在演绎金银和韩国股市的剧本。。新收录的资料对此有专业解读