TDengine is an open-sourced big data platform under GNU AGPL v3.0, designed and optimized for the Internet of Things (IoT), Connected Cars, Industrial IoT, and IT Infrastructure and Application Monitoring.
Questions tagged [tdengine]
345 questions
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System get stuck when testing stream calculation in TDengine
I want to perform stream calculations on a super table with 100,000 sub-tables in TDengine, time window of 30 minutes / slide of 5 minutes. However, the system get stuck after a time.
My stream creation statement is:
create stream calctemp_stream…
superman
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invalid SQL when using INTERVAL in TDengine
My table is :
CREATE STABLE basedb.actionlog (addtime TIMESTAMP, action_ip binary(32), modelname binary(32), acttype binary(8), remark nchar(255)) TAGS (user_id INT,username nchar(16));
The query statement is :
SELECT acttype,count(acttype) as…
JamesLiu
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How to fill a preceding non-null value when using time window in TDengine?
I have a sql statement that counts every second of status in TDengine.
SELECT first(ts),voltage FROM d1 where ts >= '2017-07-14 10:40:00.000' AND ts <= '2017-07-14 10:41:00.066' INTERVAL(1s)
There are 3 seconds of data that are missing, as shown…
superman
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report `Planner internal error` when using state_window in TDengine
I called a built-in-function diff in query. My query statement is:
select diff(ts) from ( select last(ts) as ts from lm partition by id state_window(status));
It reports " Planner internal error". I read the document carefully. I think the…
JamesLiu
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DB error when executing group by query in TDengine
I executed a query in TDengine.
My SQL statement is :
select count(distinct id_number) from attendance where project_number = "202201130002" and attendance_mark = "1" group by id_number;
It reported an error:
DB error: syntax error near "distinct…
superman
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“DB error: Invalid tbname pseudo column ” in TDengine
I encountered an error when executing the sql statement as follows in TDengine.
select task_name, group_concat(tbname, ',') as job
from (select * from meters where ts >= '2022-11-03 10:10:00' and tenant_name = 'xxx')
partition by ts
group by…
JamesLiu
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Unsupported stream query when using TDengine stream
I need to know the duration of a certain state in time series database TDengine, so I tried its stream computing.
My code is as follows:
create stream device_running_s trigger WINDOW_CLOSE watermark 60m into device_running as select…
superman
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report “Window query not supported” when using state_window in TDengine
I'm using state_window syntax in TDengine database.
My SQL statement is:
select t.*
from (
select ts,
tbname as app_id,
tenant_name,
queue_code,
task_name,
…
JamesLiu
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0
votes
1 answer
TDengine 3.0.1.8 timestamp
tdengine 3.0.1.8 test downsampling query refer to the official document can not query the timestamp
enter image description here
select max(v)-min(v) as v from u14_1759 interval(1h) limit 24;
I want to add a time column to the query results
TOM
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unable to establish connection when execute query in TDengine
I have a table in TDengine. When I execute queries like count(*) and desc, they are ok. However, when I execute a query with partition by, it reports "unable to establish connection". In my opinion, the connection is OK. This error message confused…
superman
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taosrest faile to connect TDengine
I'm using Pandas to read data from TDengine. I have a new user 'dbuser'.
My code is:
import pandas
from sqlalchemy import create_engine
engine = create_engine("taos://dbuser……")
df: pandas.DataFrame = pandas.read_sql("select * from logs",…
JamesLiu
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fail to use python connector of TDengine
I'm trying to connect TDengine through its python connector.
pip3 install taospy -U
It seems OK.
But when I execute the script, I encountered an error:
ModuleNotFoundError: No module named 'taos'
I don't know how to fix it.
I googled "No module…
superman
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0
votes
1 answer
"Client and server's time is not synchronized" in TDengine database
I'm 100% percent sure I have same time even same timezone between TDengine database server and client server ,but When I connect to server side, I still got this error :
failed to connect to server, reason: Client and server's time is not…
Yu Chen
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1 answer
Low performance when I run last_row + group by tbname in TDengine databases
this is my SQL:
select last_row(*) from test.meters where ts now-100d group by tbname;
I have 100000000 rows of data ,and it cost me 11 seconds. like this :
I don't think it is the best performance ,may I know how to improve it .
Yu Chen
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0
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Does TDengine support EXPLAIN syntax?
Many databases have EXPLAIN statements. For example, in mysql: the EXPLAIN statement provides information about how MySQL executes statements.
I find that TDengine has a reserved keyword EXPLAIN. Howerver, there is no document about it.
Can I use it…
JamesLiu
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