python - 使用 Pandas 将大型 csv 导入数据库

Question

我有一个包含约 300 万条记录的 csv 文件，我想通过我的笔记本电脑(4GB 内存)迁移到 sql server。

pandas 成功将文件读取到 DataFrame (pd.read_csv())，但是当我尝试迁移时 (.to_sql() ) 我收到内存错误:

---------------------------------------------------------------------------
MemoryError                               Traceback (most recent call last)
<ipython-input-12-94c146c2b7b7> in <module>()
----> 1 csv.to_sql(name='stats', con=engine, if_exists='append')

C:\Python27\lib\site-packages\pandas\core\generic.pyc in to_sql(self, name, con, flavor, schema, if_exists, index, index_label, chunksize, dtype)
    964             self, name, con, flavor=flavor, schema=schema, if_exists=if_exists,
    965             index=index, index_label=index_label, chunksize=chunksize,
--> 966             dtype=dtype)
    967 
    968     def to_pickle(self, path):

C:\Python27\lib\site-packages\pandas\io\sql.pyc in to_sql(frame, name, con, flavor, schema, if_exists, index, index_label, chunksize, dtype)
    536     pandas_sql.to_sql(frame, name, if_exists=if_exists, index=index,
    537                       index_label=index_label, schema=schema,
--> 538                       chunksize=chunksize, dtype=dtype)
    539 
    540 

C:\Python27\lib\site-packages\pandas\io\sql.pyc in to_sql(self, frame, name, if_exists, index, index_label, schema, chunksize, dtype)
   1170                          schema=schema, dtype=dtype)
   1171         table.create()
-> 1172         table.insert(chunksize)
   1173         # check for potentially case sensitivity issues (GH7815)
   1174         if name not in self.engine.table_names(schema=schema or self.meta.schema):

C:\Python27\lib\site-packages\pandas\io\sql.pyc in insert(self, chunksize)
    715 
    716                 chunk_iter = zip(*[arr[start_i:end_i] for arr in data_list])
--> 717                 self._execute_insert(conn, keys, chunk_iter)
    718 
    719     def _query_iterator(self, result, chunksize, columns, coerce_float=True,

C:\Python27\lib\site-packages\pandas\io\sql.pyc in _execute_insert(self, conn, keys, data_iter)
    689 
    690     def _execute_insert(self, conn, keys, data_iter):
--> 691         data = [dict((k, v) for k, v in zip(keys, row)) for row in data_iter]
    692         conn.execute(self.insert_statement(), data)
    693 

MemoryError:

还有其他方法可以让我成功迁移吗？

Answer 1

我认为你有两种方法:

1. 分块读取 csv，然后写入 SQL DB 并重复
2. 或者您可以分块写入数据库

所以对于 read_csv 有一个 chunksize参数。

同样，to_sql 也有 chunksize 参数