BigQuery异步查询作业 - fetch_results（）方法返回错误的值数 [英] BigQuery async query job - the fetch_results() method returns wrong number of values
问题描述
我正在用BigQuery Client API编写Python代码，并尝试使用异步查询代码（作为代码示例在各处编写），并且在fetch_data（）方法调用时失败。 Python错误与错误：
$ b
ValueError：解包太多值
因此，3个返回值（rows，total_count，page_token）似乎是不正确的返回值数量。但是，我找不到任何有关此方法应该返回的文档 - 除了大量代码示例只显示这3个返回结果。
以下是显示我在做什么的代码（不包括'client'变量的初始化或导入的库，这在我的代码中较早发生）。
＃--->设置并启动异步查询作业
job_id = str（uuid.uuid4（））
job = client.run_async_query（job_id，query）
job.destination = temp_tbl
job .write_disposition ='WRITE_TRUNCATE'
job.begin（）
print'job started ...'
＃--->监控工作完成
retry_count = 360
，而retry_count> 0和job.state！='DONE'：
print'等待工作完成...'
retry_count - = 1
time.sleep（1）
工作。 reload（）
if job.state =='DONE'：
print'job DONE。'
page_token = None
total_count = None
rownum = 0
job_results = job.results（）
而真：
＃---- ----下一行代码出错...
rows，total_count，page_token = job_results.fetch_data（max_results = 10，page_token = page_token）
用于行中的行：
rownum + = 1
printRow编号％d％rownum
如果page_token是None：
print'batch of end。'
break
在异步查询作业中，job_results.fetch_data（...）方法调用期望的具体返回结果是什么？
看起来就像你是对的！代码不再返回这3个参数。
正如您在提交来自公共存储库 fetch_data 现在会返回 HTTPIterator class（猜我之前没有意识到这一点，因为我有一个Docker镜像，
我发现返回结果的唯一方法就是这样做：
iterator = job_results.fetch_data（）
data = []
for page in iterator._page_iter（False）：
data.extend（[page.next（）for i in range（page.num_items）]）
请注意，现在我们不必再管理 pageTokens ，它大部分已经自动化。
：
我刚刚意识到你可以通过这样做得到结果：
results = list（job_results.fetch_data（））
承认它现在比以前更容易！
I am writing Python code with the BigQuery Client API, and attempting to use the async query code (written everywhere as a code sample), and it is failing at the fetch_data() method call. Python errors out with the error:
ValueError: too many values to unpack
So, the 3 return values (rows, total_count, page_token) seem to be the incorrect number of return values. But, I cannot find any documentation about what this method is supposed to return -- besides the numerous code examples that only show these 3 return results.
Here is a snippet of code that shows what I'm doing (not including the initialization of the 'client' variable or the imported libraries, which happen earlier in my code).
#---> Set up and start the async query job
job_id = str(uuid.uuid4())
job = client.run_async_query(job_id, query)
job.destination = temp_tbl
job.write_disposition = 'WRITE_TRUNCATE'
job.begin()
print 'job started...'
#---> Monitor the job for completion
retry_count = 360
while retry_count > 0 and job.state != 'DONE':
print 'waiting for job to complete...'
retry_count -= 1
time.sleep(1)
job.reload()
if job.state == 'DONE':
print 'job DONE.'
page_token = None
total_count = None
rownum = 0
job_results = job.results()
while True:
# ---- Next line of code errors out...
rows, total_count, page_token = job_results.fetch_data( max_results=10, page_token=page_token )
for row in rows:
rownum += 1
print "Row number %d" % rownum
if page_token is None:
print 'end of batch.'
break
What are the specific return results I should expect from the job_results.fetch_data(...) method call on an async query job?
Looks like you are right! The code no longer return these 3 parameters.
As you can see in this commit from the public repository, fetch_data now returns an instance of the HTTPIterator class (guess I didn't realize this before as I have a docker image with an older version of the bigquery client installed where it does return the 3 values).
The only way that I found to return the results was doing something like this:
iterator = job_results.fetch_data()
data = []
for page in iterator._page_iter(False):
data.extend([page.next() for i in range(page.num_items)])
Notice that now we don't have to manage pageTokens anymore, it's been automated for the most part.
[EDIT]:
I just realized you can get results by doing:
results = list(job_results.fetch_data())
Got to admit it's way easier now then it was before!
这篇关于BigQuery异步查询作业 - fetch_results（）方法返回错误的值数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
