快速获取数据框中的记录数 [英] Getting the count of records in a data frame quickly

问题描述

我有一个多达1000万条记录的数据框.如何快速计数? df.count需要很长时间.

I have a dataframe with as many as 10 million records. How can I get a count quickly? df.count is taking a very long time.

推荐答案

无论如何，这将花费很多时间.至少是第一次.

It's going to take so much time anyway. At least the first time.

一种方法是缓存数据帧，因此除了计数之外，您还可以使用它.

One way is to cache the dataframe, so you will be able to more with it, other than count.

例如

df.cache()
df.count()

后续操作不会花费很多时间.

Subsequent operations don't take much time.

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