每天学习笔记系列HIVE SQL ORDER BY 与 SORT BY
之前一直没太关注 order by 和sort by的区别,今天看了下。
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首先 ,如果在 严格模式下直接使用order by 会报错,必须加上 LIMIT关键字; In strict mode, if ORDER BY is specified, LIMIT must also be specified. set hive.mapred.mode=nonstrict;? #或者将参数值设置为,nostrictselect?*from?Awhere d =\’2018-10-22\’order by checkin_time?limit 100
sort? by 的语法不会受到set hive.mapred.mode 参数影响,
? select?*from?Awhere d =\’2018-10-22\’?sort by checkin_time?
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?distribute? by? $? ?按指定的key 去分发数据,相同key数据会被分到同一个reduce
select?*from?Awhere d =\’2018-10-22\’distribute by clientname??sort by checkin_time?#cluster by 等价于以上语句,但是cluster by 只能降序select *from Awhere d =\’2018-10-22\’ cluster by checkin_time
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