使用Python驱动程序为Cassandra创建表和索引

Question

I'm trying to automate some table and index creation from a python script using the new datastax python driver. However, it appears that certain statements are being skipped or executed out of order. I even tried putting 10 second sleep events after each command in hopes of it working, but it did not.

Usually only the second and third indexes are created. Sometimes the table creation doesn't occur before the index creation and they error out.

import logging
from cassandra.cluster import Cluster
from time import sleep


log = logging.getLogger()
log.setLevel('DEBUG')
handler = logging.StreamHandler()
handler.setFormatter(logging.Formatter("%(asctime)s [%(levelname)s] %(name)s: %(message)s"))
log.addHandler(handler)

cluster = Cluster(['128.32.xxx.xxx','128.32.xxx.xxx','128.32.xxx.xxx'])
session = cluster.connect()

session.execute("""use test;""")
#session.execute("""drop table test.devices;""")
log.info('dropped table devices.')

session.execute("""CREATE TABLE devices (
                         device_uuid uuid,
                         external_identifier text,
                         geohash text,
                         latitude float,
                         longitude float,
                         measures set<text>,
                         name text,
                         parent_device_id uuid,
                         tags map<text, text>,
                         PRIMARY KEY (device_uuid)
                       ) WITH
                         compression={'sstable_compression': 'SnappyCompressor'} USING CONSISTENCY ALL;""")

session.execute("""CREATE INDEX external_id_ind ON devices (external_identifier) USING CONSISTENCY ALL;""")

session.execute("""CREATE INDEX name_ind ON devices (name) USING CONSISTENCY ALL;""")

session.execute("""CREATE INDEX geohash_ind ON devices (geohash) USING CONSISTENCY ALL;""")

session.execute("""CREATE INDEX parent_device_id_ind ON devices (parent_device_id) USING CONSISTENCY ALL;""")

Answer 1

I believe you are writing statements using the cql3-beta syntax (The USING Consistency) which should not work with the python driver. The python driver is only meant to be used with Cassandra 1.2+ (CQL3).

The main difference is that consistency is now a state set by the client rather than a directive in the query itself. With the python driver consistency is set like so

session.execute(SimpleStatement("SELECT * FROM...", consistency_level=ConsistencyLevel.QUORUM))"