在ETL过程中,我需要从一个Postgres数据库中提取和加载一个JSON列到另一个数据库。我们使用Pandas来完成这个任务,因为它有很多读写不同源/目的地数据的方法,所有的转换都可以使用Python和Pandas编写。说实话,我们对这种方法非常满意...但是我们遇到了一个问题。
通常情况下,读写数据非常容易。你只需使用pandas.read_sql_table从源中读取数据,然后使用pandas.to_sql将其写入目标。但是,由于源表之一具有Postgres中的JSON类型列,to_sql
函数崩溃,并显示以下错误消息。
df.to_sql(table_name, analytics_db)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/pandas/core/generic.py", line 1201, in to_sql
chunksize=chunksize, dtype=dtype)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/pandas/io/sql.py", line 470, in to_sql
chunksize=chunksize, dtype=dtype)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/pandas/io/sql.py", line 1147, in to_sql
table.insert(chunksize)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/pandas/io/sql.py", line 663, in insert
self._execute_insert(conn, keys, chunk_iter)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/pandas/io/sql.py", line 638, in _execute_insert
conn.execute(self.insert_statement(), data)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 945, in execute
return meth(self, multiparams, params)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/sql/elements.py", line 263, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1053, in _execute_clauseelement
compiled_sql, distilled_params
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1189, in _execute_context
context)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1393, in _handle_dbapi_exception
exc_info
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/util/compat.py", line 202, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb, cause=cause)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/engine/base.py", line 1159, in _execute_context
context)
File "/home/ec2-user/python-virtual-environments/etl/local/lib64/python2.7/site-packages/sqlalchemy/engine/default.py", line 459, in do_executemany
cursor.executemany(statement, parameters)
sqlalchemy.exc.ProgrammingError: (psycopg2.ProgrammingError) can't adapt type 'dict'
dtype={'name_of_json_column_in_source_table': sqlalchemy.types.JSON}
仍然有效。谢谢! - nonbeing