python驱动程序分页不工作

下面是使用cassandra python驱动程序进行分页的代码

我尝试了覆盖查询和设置会话默认大小。但它们都不起作用，结果总是来自表中的所有行。我错过了什么

from cassandra.cluster import Cluster
from cassandra.query import SimpleStatement

# setup
cluster = Cluster(["10.40.10.xxx","10.40.10.xxx","10.40.22.xxx","10.40.22.xxx"])
session = cluster.connect()
session.set_keyspace("ad_realtime")
# session.default_fetch_size = 10

query = "SELECT * from campaign_offset"
statement = SimpleStatement(query, fetch_size=10)
results = session.execute(statement)

for row in results:
   print row

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Python驱动程序中的分页并不意味着只获取部分查询。这意味着一次只能获取部分查询

你的代码

for row in results:
   print row

正在调用寻呼机制。基本上，这是创建一个迭代器，该迭代器一次只请求从查询定义的结果集中提取大小为的行

使用LIMIT和WHERE子句来限制实际结果。

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您可以使用当前行获取当前页面的行，如：

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以下代码可能有助于以分页方式获取结果-

def fetch_rows(stmt: Statement, fetch_size: int = 10):
    stmt.fetch_size = fetch_size
    rs: ResultSet = session.execute(stmt)
    has_pages = rs.has_more_pages
    while has_pages:
        yield from rs.current_rows
        print ('-----------------------------------------')
        has_pages = rs.has_more_pages
        rs = session.execute(ps, paging_state=rs.paging_state)

def execute():
    query = "SELECT  col1, col2 FROM my_table WHERE some_partition_key='part_val1' AND some_clustering_col='clus_val1'"
    ps = session.prepare(query)
    for row in fetch_rows(ps, 20):
        print(row)
        # Process the row and perform desired operation

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@RussS：什么时候实际从Cassandra服务器获取数据：1还是2？1.结果=session.executestatement 2。对于结果中的行：打印行如果数据是按提取大小从服务器批量提取的，这是否意味着查询是延迟计算的。如果不是，results=session.executestatement是否从服务器获取所有数据，或者从服务器获取所需的数据，如图2所示，以获取客户端大小的数据？两者都是。Execute将获取第一页。在迭代到页面末尾时，它将获取下一个页面。查询将立即计算，但后续页面将被延迟获取。如果您愿意，resultset对象还具有一次获取整个结果的方法。

def fetch_rows(stmt: Statement, fetch_size: int = 10):
    stmt.fetch_size = fetch_size
    rs: ResultSet = session.execute(stmt)
    has_pages = rs.has_more_pages
    while has_pages:
        yield from rs.current_rows
        print ('-----------------------------------------')
        has_pages = rs.has_more_pages
        rs = session.execute(ps, paging_state=rs.paging_state)

def execute():
    query = "SELECT  col1, col2 FROM my_table WHERE some_partition_key='part_val1' AND some_clustering_col='clus_val1'"
    ps = session.prepare(query)
    for row in fetch_rows(ps, 20):
        print(row)
        # Process the row and perform desired operation