In version 3.3.4.8 of TDengine, The combination of the time series functions DISTINCT and ORDER BY triggers an internal error in the planner.

[LingweiKuang]

Bug Description

The abstract expression sequence is: SELECT DISTINCT CSUM(column), time FROM table ORDER BY time;

To Reproduce

Assume that we execute the following statement under a database named testdb.

DROP TABLE IF EXISTS t1;
CREATE TABLE t1(time TIMESTAMP, c1 INT);
INSERT INTO t1(time, c1) VALUES (1641024000000, 1), (1641024005000, 2);

# query 1
SELECT DISTINCT CSUM(c1), time FROM t1 ORDER BY time;
SELECT DISTINCT CSUM(c1), time AS ref FROM t1 ORDER BY ref;

# query 2
SELECT DISTINCT CSUM(c1), time FROM t1;

Expected Behavior

Expected result set for Query 1: 1 and 3

Expected result set for Query 2: 1 and 3

Actual behaviour

Query 1 returned result set: DB error: Planner internal error

Query 2 returned result set: 1 and 3

Environment

• OS：Ubuntu Server 22.04 LTS 64bit
• TDengine Version：3.3.4.8

Additional Context

Hello, TDengine team. When I combine time series-specific functions with DISTINCT and sort the data by the time field, the TDengine planner returns an internal error. This may be a potential crash error in the planner. Not only the CSUM function triggers this error, but other time series-specific functions also cause this error.

[LingweiKuang]