pyarrow可以将多个parquet文件写入像fastparquet的file_scheme ='hive'选项这样的文件夹吗？ [英] Can pyarrow write multiple parquet files to a folder like fastparquet's file_scheme='hive' option?

问题描述

我有一个数百万条记录SQL表，我打算使用pyarrow库向一个文件夹中的许多parquet文件写出数据。数据内容似乎太大，无法存储在单个实木复合地板文件中。

然而，我似乎无法通过pyarrow库找到一个API或参数，它允许我指定如下所示：

  file_scheme =hive
  

由fastparquet python库支持。

以下是我的示例代码：

 ＃！/ usr / bin / python 
 
导入pyodbc 
将pandas导入为pd 
将pyarrow导入为pa 
进口pyarrow.parquet如PQ 
 
 conn_str = 'UID =用户名; PWD = passwordHere;' + 
 'DRIVER = freetds的; SERVERNAME =的myconfig; DATABASE = MYDB' 
 
＃---->查询SQL数据库到数据帧的熊猫
康恩= pyodbc.connect（conn_str，自动提交= FALSE）
 SQL = SELECT * FROM ClientAccount（NOLOCK） 
 DF = pd.io.sql .read_sql（sql，conn）
 
 
＃---->将数据框转换为pyarrow表并将其写出
 table = pa.Table.from_pandas（df）
 pq.write_table（table，'./clients/'）
  
 
 
 
这会引发错误：
 
 
 文件/usr/local/lib/python2.7/dist-packages/pyarrow/parquet.py，第912行，写入表
 os.remove（其中）
 OSError：[Errno 21]是一个目录：'./clients/'
  
如果我用下面的代码替换最后一行，很好，但只写了一个大文件： 
 
 
  pq.write_table（table，'./clients.parquet'）
  
任何想法如何使用pyarrow执行多文件输出？
解决方案
试试 pyarrow.parquet.write_to_dataset   https://github.com/apache/arrow/blob/master/python/pyarrow/parquet.py#L938 。 
 
 
 
我打开了 https：/ /issues.apache.org/jira/browse/ARROW-1858 有关添加更多文档的信息。
 
 
 
我建议寻求对Apache Arrow的支持。邮件列表[e-mail]。谢谢！
 
I have a multi-million record SQL table that I'm planning to write out to many parquet files in a folder, using the pyarrow library.  The data content seems too large to store in a single parquet file.

However, I can't seem to find an API or parameter with the pyarrow library that allows me to specify something like:
file_scheme="hive"
As is supported by the fastparquet python library.

Here's my sample code:
#!/usr/bin/python

import pyodbc
import pandas as pd
import pyarrow as pa
import pyarrow.parquet as pq

conn_str = 'UID=username;PWD=passwordHere;' + 
    'DRIVER=FreeTDS;SERVERNAME=myConfig;DATABASE=myDB'

#----> Query the SQL database into a Pandas dataframe
conn = pyodbc.connect( conn_str, autocommit=False)
sql = "SELECT * FROM ClientAccount (NOLOCK)"
df = pd.io.sql.read_sql(sql, conn)


#----> Convert the dataframe to a pyarrow table and write it out
table = pa.Table.from_pandas(df)
pq.write_table(table, './clients/' )
This throws an error:
File "/usr/local/lib/python2.7/dist-packages/pyarrow/parquet.py", line 912, in write_table
    os.remove(where)
OSError: [Errno 21] Is a directory: './clients/'
If I replace that last line with the following, it works fine but writes only one big file:
pq.write_table(table, './clients.parquet' )
Any ideas how I can do the multi-file output thing with pyarrow?
解决方案
Try pyarrow.parquet.write_to_dataset https://github.com/apache/arrow/blob/master/python/pyarrow/parquet.py#L938. 

I opened https://issues.apache.org/jira/browse/ARROW-1858 about adding some more documentation about this.

I recommend seeking support for Apache Arrow on the mailing list [e-mail]. Thanks!

                        
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