async def execute(query,
params=None,
consistency_level=None,
timeout=conn.NOT_SET,
connection=None):
"""执行 cassandra 操作"""
_connection = conn.get_connection(connection)
if isinstance(query, SimpleStatement):
pass #
elif isinstance(query, BaseCQLStatement):
params = query.get_context()
query = SimpleStatement(str(query),
consistency_level=consistency_level,
fetch_size=query.fetch_size)
elif isinstance(query, str):
query = SimpleStatement(query, consistency_level=consistency_level)
# debug_query = conn.format_log_context(query.query_string,
# connection=connection)
# print(debug_query)
result = await _connection.session.execute_future(query,
params,
timeout=timeout)
return result
async def execute(
query,
params=None,
consistency_level=None,
timeout=conn.NOT_SET,
connection=None,
):
"""
Based on cassandra.cqlengine.connection.execute
"""
_connection = conn.get_connection(connection)
if isinstance(query, SimpleStatement):
pass #
elif isinstance(query, BaseCQLStatement):
params = query.get_context()
query = SimpleStatement(
str(query),
consistency_level=consistency_level,
fetch_size=query.fetch_size,
)
elif isinstance(query, str):
query = SimpleStatement(query, consistency_level=consistency_level)
result = await _connection.session.execute_future(query,
params,
timeout=timeout)
return result
async def async_fetch(cls, fields, fetch_size, paging_state):
"""分页获取
Todo: 验证 paging_state 是否合法
:param fields: list
:param fetch_size: int
:param paging_state: str
:return ResultSet, bytes
"""
# 解析 paging_state 为合法 bytes 对象
if paging_state is None:
_paging_state = None
else:
_paging_state = base64.b64decode(paging_state.encode())
# 构造 cql 语句
_fields_str = ', '.join(fields)
statement = SimpleStatement(
f'SELECT {_fields_str} FROM {cls.column_family_name()}',
fetch_size=fetch_size)
connection = conn.get_connection()
# 查询数据库
result_set = await connection.session.execute_future(
statement, paging_state=_paging_state)
results = [cls(**result) for result in result_set.current_rows]
# 使用 base64 编码新的 paging_state
if result_set.paging_state is None:
new_paging_state = None
else:
new_paging_state = base64.b64encode(result_set.paging_state)
return results, new_paging_state
async def async_iterate(cls,
fetch_size: int,
fields: list = None,
limit: int = None):
"""Iteration by fetch_size
"""
statement = SimpleStatement(str(
SelectStatement(cls.column_family_name(),
fields=fields,
limit=limit)),
fetch_size=fetch_size)
connection = conn.get_connection()
paging_state = None
while True:
# Execute query
result_set = await connection.session.execute_future(
statement, paging_state=paging_state)
yield [cls(**result) for result in result_set.current_rows]
paging_state = result_set.paging_state
# End
if paging_state is None:
break