将非常大的数据集传输到fiware后端：SourceDB ->Orion -> Cygnus -> Postgres。为此，我编写了一个python脚本来获取行，并为获取的每一行将有效负载发送到Orion。
该脚本以150ms（0.15秒）的间隔触发，但是令我惊讶的是，大约10次迭代后，只有两个值（发送的第一个和最后一个有效载荷）被持久保存到Postgres接收器中。意味着80％的数据集没有持久化到接收器中。
脚本：
import psycopg2
from time import sleep
from config import config
from tqdm import tqdm
import requests
import json
def val_json():
db = "select to_json(d) from ( select \
n.noise_data as measurand, \
n.factor as \"sonometerClass\", \
to_timestamp(n.seconds) as \"dateObserved\", \
l.description as name, \
json_build_object( \
'coordinates', \
json_build_array(l.node_lon, l.node_lat) \
) as location \
from noise as n \
inner join deployment as d on \
d.deployment_id = n.deployment_id \
inner join location as l on \
l.location_id = d.location_id \
order by n.seconds asc \
) as d"
return db
def main():
url = 'http://localhost:1026/v2/entities/002/attrs?options=keyValues'
headers = {"Content-Type": "application/json", \
"fiware-service": "urbansense", \
"fiware-servicepath": "/basic"}
conn = None
try:
params = config()
with psycopg2.connect(**params) as conn:
with conn.cursor(name='my_cursor') as cur:
cur.itersize = 5000
cur.execute(val_json())
for row in tqdm(cur):
jsonData = json.dumps(row)
if jsonData.startswith('[') and jsonData.endswith(']'):
jsonData = jsonData[1:-1]
print()
print(jsonData)
requests.post(url, data= jsonData, headers=headers)
sleep(0.15)
cur.close()
except (Exception, psycopg2.DatabaseError) as error:
print(error)
finally:
if conn is not None:
conn.close()
if __name__ == '__main__':
main()
前十次迭代（有效负载）
$python3 noiselevelObserved.py
0it [00:00, ?it/s]
{"measurand": 64.8, "sonometerClass": 1, "dateObserved": "1970-01-01T01:00:15+01:00", "name": "Trindade", "location": {"coordinates": [-8.609973, 41.151943]}}
1it [00:00, 1.75it/s]
{"measurand": 58.8, "sonometerClass": 0, "dateObserved": "1970-01-01T01:00:16+01:00", "name": "Trindade", "location": {"coordinates": [-8.609973, 41.151943]}}
2it [00:00, 2.23it/s]
{"measurand": 56.5, "sonometerClass": 0, "dateObserved": "1970-01-01T01:00:17+01:00", "name": "Trindade", "location": {"coordinates": [-8.609973, 41.151943]}}
3it [00:00, 2.76it/s]
{"measurand": 61.1, "sonometerClass": 1, "dateObserved": "1970-01-01T01:00:18+01:00", "name": "Casa da Musica", "location": {"coordinates": [-8.63041, 41.158091]}}
4it [00:01, 3.31it/s]
{"measurand": 108.5, "sonometerClass": 2, "dateObserved": "1970-01-01T01:00:18+01:00", "name": "Pr. Liberdade Cardosas", "location": {"coordinates": [-8.611119, 41.146023]}}
5it [00:01, 3.86it/s]
{"measurand": 56.5, "sonometerClass": 0, "dateObserved": "1970-01-01T01:00:18+01:00", "name": "Trindade", "location": {"coordinates": [-8.609973, 41.151943]}}
6it [00:01, 4.35it/s]
{"measurand": 59.9, "sonometerClass": 1, "dateObserved": "1970-01-01T01:00:19+01:00", "name": "Casa da Musica", "location": {"coordinates": [-8.63041, 41.158091]}}
7it [00:01, 4.78it/s]
{"measurand": 97.2, "sonometerClass": 2, "dateObserved": "1970-01-01T01:00:19+01:00", "name": "D. Manuel II", "location": {"coordinates": [-8.625192, 41.148558]}}
8it [00:01, 5.12it/s]
{"measurand": 108.6, "sonometerClass": 2, "dateObserved": "1970-01-01T01:00:19+01:00", "name": "Pr. Liberdade Cardosas", "location": {"coordinates": [-8.611119, 41.146023]}}
9it [00:01, 5.41it/s]
{"measurand": 57.1, "sonometerClass": 0, "dateObserved": "1970-01-01T01:00:19+01:00", "name": "Trindade", "location": {"coordinates": [-8.609973, 41.151943]}}
10it [00:02, 5.63it/s]
{"measurand": 53.9, "sonometerClass": 0, "dateObserved": "1970-01-01T01:00:20+01:00", "name": "Casa da Musica", "location": {"coordinates": [-8.63041, 41.158091]}}
读取属性的值会保留在postgres中
postgres=# select * from urbansense.basic_002_noiselevelobserved ;
recvtimets | recvtime | fiwareservicepath | entityid | entitytype | attrname | attrtype | attrvalue | attrmd
---------------+--------------------------+-------------------+----------+--------------------+----------------+-----------------+---------------------------------------+--------
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | dateObserved | Text | 1970-01-01T01:00:15+01:00 | []
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | latitude | Number | 41.1591 | []
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | location | StructuredValue | {"coordinates":[-8.609973,41.151943]} | []
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | longitude | Number | -8.65915 | []
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | measurand | Number | 64.8 | []
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | name | Text | Trindade | []
1559045918129 | 2019-05-28T12:18:38.129Z | /basic | 002 | NoiseLevelObserved | sonometerClass | Number | 1 | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | dateObserved | Text | 1970-01-01T01:00:20+01:00 | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | latitude | Number | 41.1591 | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | location | StructuredValue | {"coordinates":[-8.63041,41.158091]} | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | longitude | Number | -8.65915 | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | measurand | Number | 53.9 | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | name | Text | Casa da Musica | []
1559045919723 | 2019-05-28T12:18:39.723Z | /basic | 002 | NoiseLevelObserved | sonometerClass | Number | 0 | []
(14 rows)
将触发频率更改为1秒的间隔并没有太大改善，仅保留了3个结果集（有效负载）（丢失了70％）：
postgres=# select * from urbansense.basic_002_noiselevelobserved ;
recvtimets | recvtime | fiwareservicepath | entityid | entitytype | attrname | attrtype | attrvalue | attrmd
---------------+--------------------------+-------------------+----------+--------------------+----------------+-----------------+---------------------------------------+--------
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | dateObserved | Text | 1970-01-01T01:00:15+01:00 | []
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | latitude | Number | 41.1591 | []
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | location | StructuredValue | {"coordinates":[-8.609973,41.151943]} | []
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | longitude | Number | -8.65915 | []
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | measurand | Number | 64.8 | []
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | name | Text | Trindade | []
1559046840569 | 2019-05-28T12:34:00.569Z | /basic | 002 | NoiseLevelObserved | sonometerClass | Number | 1 | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | dateObserved | Text | 1970-01-01T01:00:18+01:00 | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | latitude | Number | 41.1591 | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | location | StructuredValue | {"coordinates":[-8.609973,41.151943]} | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | longitude | Number | -8.65915 | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | measurand | Number | 56.5 | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | name | Text | Trindade | []
1559046845620 | 2019-05-28T12:34:05.620Z | /basic | 002 | NoiseLevelObserved | sonometerClass | Number | 0 | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | dateObserved | Text | 1970-01-01T01:00:20+01:00 | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | latitude | Number | 41.1591 | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | location | StructuredValue | {"coordinates":[-8.63041,41.158091]} | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | longitude | Number | -8.65915 | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | measurand | Number | 53.9 | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | name | Text | Casa da Musica | []
1559046850679 | 2019-05-28T12:34:10.679Z | /basic | 002 | NoiseLevelObserved | sonometerClass | Number | 0 | []
(21 rows)
老实说，我不希望将触发速度提高到一秒，因为要迁移数据量以继续我的研究。当我第一次以1秒的间隔进行尝试时，我意识到要花几个月的时间（可能是4个月）才能完成。
问题：：Orion CB（或也许Cygnus）的构建方式不具备以这样的速率（150ms / 0.15s）接收实体/属性值的能力，还是Cygnus不够聪明以至无法以这样的速率接收来自Orion的通知？
我会建议您确保所有值在最短的时间内保持不变。
答案 0 :(得分：2)
基于问题注释中的讨论，解决方案是删除订阅中的throttling参数。这是有道理的：节流使得某些通知没有发送（在这种情况下，占所有通知的80％）。