Hive的hour（）函数返回12小时时钟值 [英] Hive's hour() function returns 12 hour clock value

问题描述

根据文档Hives标准函数hour（）应该返回一个0到24之间的值，但由于某种原因，我总是得到一个12小时的时钟值，介于0和12之间。我使用 MySQLDateTime 字段作为我的Hive表中的时间戳字段。任何人都知道问题可能是什么？

解决方案

我想我找到了它。我查看了源代码，显然 UDFHour.java 确实有两个 evaluate（）函数。一个接受 Text 对象作为参数，另一个使用 TimeStampWritable 对象作为参数。这两个函数都使用 Calendar 实例，但由于某种原因，第一个函数返回值 Calendar.HOUR_OF_DAY ，第二个函数 Calendar.HOUR 。

我查看了蜂巢文档，但找不到第二个函数的任何内容，但它在那里。我使用的Hive 0.9.0.16与Hortonworks的HDP一起提供。

编辑：
我已经报道过这个一段时间以前。现在有一个补丁： https://issues.apache.org/jira/browse/HIVE -3850 。

According to the documentation Hives standard function hour() should return a value between 0 and 24 but for some reason I always get a twelve hour clock value, between 0 and 12. I'm using a MySQLDateTime field as a Timestamp field in my Hive table. Anyone know what the problem might be?

解决方案

I think I found it. I looked at the source code and apparently UDFHour.java does have two evaluate() functions. One that does accept a Text object as parameter and one that uses a TimeStampWritable object as parameter. Both work with a Calendar instance but for some reason the first function returns the value of Calendar.HOUR_OF_DAY and the second one Calendar.HOUR.

I've looked in the Hives documentation but I couldn't find anything about that second function, but it's there. I'm using Hive 0.9.0.16, which came with Hortonworks' HDP.

Edit: I've reported this a while back. A patch is now available: https://issues.apache.org/jira/browse/HIVE-3850.

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