I'm attempting to fetch data from Exasol using PyExasol, in parallel. I'm following the example here - https://github.com/badoo/pyexasol/blob/master/examples/14_parallel_export.py
My code looks like this :
import multiprocessing
import pyexasol
import pyexasol.callback as cb
class ExportProc(multiprocessing.Process):
def __init__(self, node):
self.node = node
self.read_pipe, self.write_pipe = multiprocessing.Pipe(False)
super().__init__()
def start(self):
super().start()
self.write_pipe.close()
def get_proxy(self):
return self.read_pipe.recv()
def run(self):
self.read_pipe.close()
http = pyexasol.http_transport(self.node['host'], self.node['port'], pyexasol.HTTP_EXPORT)
self.write_pipe.send(http.get_proxy())
self.write_pipe.close()
pd1 = http.export_to_callback(cb.export_to_pandas, None)
print(f"{self.node['idx']}:{len(pd)}")
EXASOL_HOST = "<IP-ADDRESS>:8563"
EXASOL_USERID = "username"
EXASOL_PASSWORD = "password"
c = pyexasol.connect(dsn=EXASOL_HOST, user=EXASOL_USERID, password=EXASOL_PASSWORD, compression=True)
nodes = c.get_nodes(10)
pool = list()
proxy_list = list()
for n in nodes:
proc = ExportProc(n)
proc.start()
proxy_list.append(proc.get_proxy())
pool.append(proc)
c.export_parallel(proxy_list, "SELECT * FROM SOME_SCHEMA.SOME_TABLE", export_params={'with_column_names': True})
stmt = c.last_statement()
r = stmt.fetchall()
At the last statement, I'm getting the following error and unable to fetch any results.
---------------------------------------------------------------------------
ExaRuntimeError Traceback (most recent call last)
<command-911615> in <module>
----> 1 r = stmt.fetchall()
/local_disk0/pythonVirtualEnvDirs/virtualEnv-01515a25-967f-4b98-aa10-6ac03c978ce2/lib/python3.7/site-packages/pyexasol/statement.py in fetchall(self)
85
86 def fetchall(self):
---> 87 return [row for row in self]
88
89 def fetchcol(self):
/local_disk0/pythonVirtualEnvDirs/virtualEnv-01515a25-967f-4b98-aa10-6ac03c978ce2/lib/python3.7/site-packages/pyexasol/statement.py in <listcomp>(.0)
85
86 def fetchall(self):
---> 87 return [row for row in self]
88
89 def fetchcol(self):
/local_disk0/pythonVirtualEnvDirs/virtualEnv-01515a25-967f-4b98-aa10-6ac03c978ce2/lib/python3.7/site-packages/pyexasol/statement.py in __next__(self)
53 if self.pos_total >= self.num_rows_total:
54 if self.result_type != 'resultSet':
---> 55 raise ExaRuntimeError(self.connection, 'Attempt to fetch from statement without result set')
56
57 raise StopIteration
ExaRuntimeError:
(
message => Attempt to fetch from statement without result set
dsn => <IP-ADDRESS>:8563
user => username
schema =>
)
It seems that the type of the returned statement is not 'resultSet' but 'rowCount'. Any help on what I'm doing wrong or why the type of statement is ''rowCount' ?
