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example.py
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import asyncio
from aiocassandra import aiosession
from cassandra.cluster import Cluster
from cassandra.query import SimpleStatement
# connection is blocking call
cluster = Cluster()
# aiocassandra uses executor_threads to talk to cassndra driver
# https://datastax.github.io/python-driver/api/cassandra/cluster.html?highlight=executor_threads
session = cluster.connect()
async def main():
# patches and adds `execute_future`, `execute_futures` and `prepare_future`
# to `cassandra.cluster.Session`
aiosession(session)
# best way is to use cassandra prepared statements
# https://cassandra-zone.com/prepared-statements/
# https://datastax.github.io/python-driver/api/cassandra/cluster.html#cassandra.cluster.Session.prepare
# try to create them once on application init
query = session.prepare('SELECT now() FROM system.local;')
# if non-blocking prepared statements is really needed:
query = await session.prepare_future('SELECT now() FROM system.local;')
print(await session.execute_future(query))
# pagination is also supported
query = 'SELECT * FROM system.size_estimates;'
statement = SimpleStatement(query, fetch_size=100)
# don't miss *s* (execute_futureS)
async with session.execute_futures(statement) as paginator:
async for row in paginator:
print(row)
loop = asyncio.get_event_loop()
loop.run_until_complete(main())
cluster.shutdown()
loop.close()