文章浏览阅读547次。一、解决数据倾斜1. 过滤掉null部分key值存在大量空字段,会hash到同一reduce,造成reduce长尾,将null 值过滤掉举例: select user_id from logs where statdate = '20170815' where user_id is not null;2. hive join倾斜:设置join skew参数......
文章浏览阅读113次。mysqlSELECT (SELECT COUNT(*) FROM pb_subscribe_message psm RIGHT JOIN pb_subscribe_message_details psmd ON psm.subscribe_code=psmd.subscribe_code WHEREpsmd.approve_state='0'-- 下列条件,可以用mybatis的动态sql做if判断AND DATE_FORMAT......