Question

使用javascript时如何使用BigQuery进行分页

首先我发送请求：

var request = gapi.client.bigquery.jobs.query({
    'projectId': project_id,
    'timeoutMs': '30000',
    'query': query,
    'maxResults' : 50,
    'pageToken': pageToken
   });

此查询将返回前50个结果，然后如何检索接下来的50个结果。我想使用javascript和Bigquery动态分页。

查询：

SELECT year, month,day,state,mother_age, AVG(weight_pounds) as AvgWeight FROM [publicdata:samples.natality] Group EACH By year, month,day,state, mother_age

这是我正在使用的查询。

Answer 1

TableData.list有效，或者您可以使用jobs.getQueryResults()，这通常是获取查询结果的首选方式（因为它也可以等待查询完成）。

您应该使用从原始查询响应或之前的jobs.getQueryResults()调用返回的页面标记来遍历页面。这通常比使用基于索引的分页更有效和可靠。

我没有javascript示例，但这里有一个使用python的示例应该相对容易适应：

from apiclient.discovery import build

def run_query(http, service, project_id, query, response_handler,
              timeout=30*1000, max_results=1024):
  query_request = {
      'query': query,
      'timeoutMs': timeout,
      'maxResults': max_results}
  print 'Running query "%s"' % (query,)
  response = service.jobs().query(projectId=project_id,
      body=query_request).execute(http)
  job_ref = response['jobReference']

  get_results_request = {
      'projectId': project_id,
      'jobId': job_ref['jobId'],
      'timeoutMs': timeout,
      'maxResults': max_results}

  while True:
    print 'Response %s' % (response,)
    page_token = response.get('pageToken', None)
    query_complete = response['jobComplete']
    if query_complete:
      response_handler(response)
      if page_token is None:
        # Our work is done, query is done and there are no more
        # results to read.
        break;
    # Set the page token so that we know where to start reading from.
    get_results_request['pageToken'] = page_token
    # Apply a python trick here to turn the get_results_request dict
    # into method arguments.
    response = service.jobs().getQueryResults(
        **get_results_request).execute(http)

def print_results(results):
  fields = results['schema']['fields']
  rows = results['rows']
  for row in rows:
    for i in xrange(0, len(fields)):
      cell = row['f'][i]
      field = fields[i]
      print "%s: %s " % (field['name'], cell['v']),
    print ''

def run(http, query):
  service = build('bigquery', 'v2')
  project_id = '#Your Project Here#'
  run_query(http, service, project_id, query, print_results,
           timeout=1)

Answer 2

查询运行后，所有结果都将保存到临时表中（如果已设置相应的标志，则为永久表）。

您可以使用tabledata.list阅读这些结果。请注意，它提供了startIndex参数，因此您也可以跳转到任意页面，而不仅仅是下一页。

https://developers.google.com/bigquery/docs/reference/v2/tabledata/list

BigQuery分页

2 个答案: