将熊猫数据框上传到redshift-关系“ sqlite_master”不存在

时间:2019-11-22 11:14:19

标签: pandas amazon-redshift

我正在尝试将熊猫的数据帧写入redshift。

这是代码

df = pd.DataFrame({'num_legs': [2, 4, 8, 0],
                   'num_wings': [2, 0, 0, 0],
                   'num_specimen_seen': [10, 2, 1, 8]},
                  index=['falcon', 'dog', 'spider', 'fish'])

from sqlalchemy import create_engine
import sqlalchemy
sql_engine = create_engine('postgresql://username:password@host:port/dbname')
conn = sql_engine.raw_connection()

df.to_sql('tmp_table', conn, index = False, if_exists = 'replace')

但是,出现以下错误

    ---------------------------------------------------------------------------
    UndefinedTable                            Traceback (most recent call last)
    ~/opt/anaconda3/envs/UserExperience/lib/python3.7/site-packages/pandas/io/sql.py in execute(self, *args, **kwargs)
       1594             else:
    -> 1595                 cur.execute(*args)
       1596             return cur

    UndefinedTable: relation "sqlite_master" does not exist
...
...
...

   1593                 cur.execute(*args, **kwargs)
   1594             else:
-> 1595                 cur.execute(*args)
   1596             return cur
   1597         except Exception as exc:

DatabaseError: Execution failed on sql 'SELECT name FROM sqlite_master WHERE type='table' AND name=?;': relation "sqlite_master" does not exist

我尝试使用pandas_redshift用户,但是似乎第一个用户必须上传到s3存储桶,然后再上传到redshift。我想直接上传。同样,Here我认为答案建议先上传到s3,然后再上传到redshift

我可以使用相同的连接读取数据库并进行查询。

1 个答案:

答案 0 :(得分:3)

尝试使用sql_engine代替conn。

我只是遇到了同样的问题,使用 engine 可以解决问题,请尝试以下操作:

import sqlalchemy

engine = sqlalchemy.create_engine('postgres://username:password@url:5439/db_name')
print(bool(engine)) # <- just to keep track of the process

with engine.connect() as conn:
    print(bool(conn)) # <- just to keep track of the process

    df.to_sql(name=table_name, con=engine)
    print("end") # <- just to keep track of the process

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