Python Dask客户机&x2B；read_sql_表：distributed.protocol.core-严重-序列化失败_Python_Dask_Dask Dataframe

Python Dask客户机&x2B；read_sql_表：distributed.protocol.core-严重-序列化失败

python dask

Python Dask客户机&x2B；read_sql_表：distributed.protocol.core-严重-序列化失败,python,dask,dask-dataframe,Python,Dask,Dask Dataframe,正在尝试使用dask.distributed Client运行read\u sql\u table，其中该表是一个查询，因为我不想获取整个表。下面的例子 import dask.dataframe as dd from dask.distributed import Client client = Client() sql = select([schema.datetime, # DateTime format schema.id]) \ #

正在尝试使用

dask.distributed Client

运行

read\u sql\u table

，其中该表是一个查询，因为我不想获取整个表。下面的例子

import dask.dataframe as dd
from dask.distributed import Client

client = Client()
sql = select([schema.datetime,     # DateTime format
              schema.id]) \        # UUID
        .select_from(schema) \     # schema class (see below)
        .where(schema.datetime.between(start_dt, end_dt))
table = aliased(sql, name='table')
response = dd.read_sql_table(table=table, uri='uri', schema='schema', index_col='datetime')

对于

打印（响应）

，我得到了预期的输出：

Dask DataFrame Structure:
                        swing_id
npartitions=1                   
2020-08-03 07:16:59.590   object
2020-08-29 23:34:44.980      ...
Dask Name: from-delayed, 2 tasks

但是，当我开始使用

dask.dataframe

像

print（response.head（））

一样时，我得到一个

无法序列化的错误：
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - WARNING - Error in batched write, retrying
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - WARNING - Error in batched write, retrying
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - WARNING - Error in batched write, retrying
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - WARNING - Error in batched write, retrying
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - WARNING - Error in batched write, retrying
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - WARNING - Error in batched write, retrying
distributed.protocol.core - CRITICAL - Failed to Serialize
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.comm.utils - ERROR - ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
distributed.batched - ERROR - Error in batched write
Traceback (most recent call last):
  File ".\.conda\envs\project-name\lib\site-packages\distributed\batched.py", line 93, in _background_send
    nbytes = yield self.comm.write(
  File ".\.conda\envs\project-name\lib\site-packages\tornado\gen.py", line 735, in run
    value = future.result()
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\tcp.py", line 223, in write
    frames = await to_frames(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 54, in to_frames
    return _to_frames()
  File ".\.conda\envs\project-name\lib\site-packages\distributed\comm\utils.py", line 34, in _to_frames
    protocol.dumps(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 50, in dumps
    data = {
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\core.py", line 51, in <dictcomp>
    key: serialize(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\protocol\serialize.py", line 277, in serialize
    raise TypeError(msg, str(x)[:10000])
TypeError: ('Could not serialize object of type tuple.', "(<function safe_head at 0x00000000053B88B0>, (<function check_meta at 0x0000000005387EE0>, (<function apply at 0x0000000002AB3280>, <function _read_sql_chunk at 0x0000000005450AF0>, [<sqlalchemy.sql.selectable.Select at 0x99f8ca0; Select object>, 'postgresql://tirisdspgadmin@tirisdspgserver:wsiNTobyx8opPo2imfCB@tirisdspgserver.postgres.database.azure.com/mav', Empty DataFrame\nColumns: [swing_id]\nIndex: []], (<class 'dict'>, [['engine_kwargs', (<class 'dict'>, [])], ['index_col', 'start_time']])), Empty DataFrame\nColumns: [swing_id]\nIndex: [], 'from_delayed'), 5)")
Traceback (most recent call last):
  File "./project-name/src/points_bulk_scripts/extract_features.py", line 24, in <module>
    print(swings.head())
  File ".\.conda\envs\project-name\lib\site-packages\dask\dataframe\core.py", line 1006, in head
    return self._head(n=n, npartitions=npartitions, compute=compute, safe=True)
  File ".\.conda\envs\project-name\lib\site-packages\dask\dataframe\core.py", line 1039, in _head
    result = result.compute()
  File ".\.conda\envs\project-name\lib\site-packages\dask\base.py", line 167, in compute
    (result,) = compute(self, traverse=False, **kwargs)
  File ".\.conda\envs\project-name\lib\site-packages\dask\base.py", line 452, in compute
    results = schedule(dsk, keys, **kwargs)
  File ".\.conda\envs\project-name\lib\site-packages\distributed\client.py", line 2725, in get
    results = self.gather(packed, asynchronous=asynchronous, direct=direct)
  File ".\.conda\envs\project-name\lib\site-packages\distributed\client.py", line 1986, in gather
    return self.sync(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\client.py", line 832, in sync
    return sync(
  File ".\.conda\envs\project-name\lib\site-packages\distributed\utils.py", line 340, in sync
    raise exc.with_traceback(tb)
  File ".\.conda\envs\project-name\lib\site-packages\distributed\utils.py", line 324, in f
    result[0] = yield future
  File ".\.conda\envs\project-name\lib\site-packages\tornado\gen.py", line 735, in run
    value = future.result()
  File ".\.conda\envs\project-name\lib\site-packages\distributed\client.py", line 1852, in _gather
    raise exc
concurrent.futures._base.CancelledError: ('head-1-5-from-delayed-97944bbb0c6f5129ccb48a1f7c36d62b', 0)

另外，如果我阅读了整个表，而没有查询，那么它将与客户端一起工作：
import dask.dataframe as dd
from dask.distributed import Client

client = Client()
response = dd.read_sql_table(table=<SQLAlchemy table>, uri='uri', schema='schema', index_col='index')
print(response.head())

client.get\u版本（check=True）
：
schema
class
from sqlalchemy import Column, String, Integer, TIMESTAMP, Boolean
from sqlalchemy.ext.declarative import declarative_base


class Schema(declarative_base()):

    __tablename__ = "table_name"

    datetime = Column(TIMESTAMP, primary_key=True)
    id = Column(String, primary_key=True)

我相信这是你问题的一部分：
.select_from(schema)

其中，schema
引用了一个实际的数据库连接
您应该使用字符串表、模式和列来引用一个完全抽象的表达式。例如，这是来自测试的
from sqlalchemy import sql
query = sql.select([sql.column("number"), sql.column("name")]).select_from(
        sql.table("test")
    )

（我想
你能分享你的查询语句吗，或者是最简单的失败形式吗？我编辑了答案，将查询包含在最简单的形式中，它是一个，其中start_dt和end_dt之间的datetime顺便问一句，以及返回一个异常，你的工作人员在评估过程中存活还是死亡？ping-这是一个有趣的问题细节
from sqlalchemy import Column, String, Integer, TIMESTAMP, Boolean
from sqlalchemy.ext.declarative import declarative_base


class Schema(declarative_base()):

    __tablename__ = "table_name"

    datetime = Column(TIMESTAMP, primary_key=True)
    id = Column(String, primary_key=True)

.select_from(schema)

from sqlalchemy import sql
query = sql.select([sql.column("number"), sql.column("name")]).select_from(
        sql.table("test")
    )