apache-spark - pyspark 在一次加载中加载多个分区文件

Question

我正在尝试在一次加载中加载多个文件。都是分区文件当我用 1 个文件尝试它时，它可以工作，但是当我列出 24 个文件时，它给了我这个错误，除了在加载后进行联合之外，我找不到任何有关限制的文档和解决方法。还有其他选择吗？

下面的代码可以重现问题:

basepath = '/file/' 
paths = ['/file/df201601.orc', '/file/df201602.orc', '/file/df201603.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc',  
         '/file/df201604.orc', '/file/df201605.orc', '/file/df201606.orc', ]   

df = sqlContext.read.format('orc') \
               options(header='true',inferschema='true',basePath=basePath)\
               .load(*paths)

收到错误:

 TypeError                                 Traceback (most recent call last)
 <ipython-input-43-7fb8fade5e19> in <module>()

---> 37 df = sqlContext.read.format('orc')                .options(header='true', inferschema='true',basePath=basePath)                .load(*paths)
     38 

TypeError: load() takes at most 4 arguments (24 given)

Answer 1

如 the official documentation 中所述，要读取多个文件，您应该传递一个列表:

path – optional string or a list of string for file-system backed data sources.

所以在你的情况下:

(sqlContext.read
    .format('orc') 
    .options(basePath=basePath)
    .load(path=paths))

仅当使用可变参数定义 load 时，参数解包 (*) 才有意义，例如:

def load(this, *paths):
    ...