apache / iotdb

Apache IoTDB
https://iotdb.apache.org/
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[Bug] The CAST operator has a logical error causing precision loss when converting floating-point values. #14149

Open LingweiKuang opened 3 days ago

LingweiKuang commented 3 days ago

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Version

version 1.3.3 (Build: ad95a7e)

Describe the bug and provide the minimal reproduce step

DROP DATABASE root.db0
CREATE DATABASE root.db0

CREATE TIMESERIES root.db0.t1 WITH datatype=FLOAT compressor=GZIP 'MAX_POINT_NUMBER'='6';
INSERT INTO root.db0(timestamp, t1) VALUES (1643027794590, 0.5522);
INSERT INTO root.db0(timestamp, t1) VALUES (1643027794600, 0.8044);

# query 1
select t1 from root.db0 where t1 <= 0.8044

# query 2
select t1 from root.db0 where cast(t1 as float) <= 0.8044

What did you expect to see?

Query 1 returned result set: 0.5522 and 0.8044

Query 2 returned result set: 0.5522 and 0.8044

What did you see instead?

Query 1 returned result set: 0.5522 and 0.8044

Query 2 returned result set: 0.5522

Anything else?

Dear IoTDB team, When using the CAST operator to convert a FLOAT value to FLOAT, the value theoretically should remain unchanged. However, the above test case indicates that a logical error causing precision loss occurs after the CAST conversion.

Are you willing to submit a PR?

LingweiKuang commented 3 days ago

The CAST operator has a logical error causing precision loss when converting floating-point values

CritasWang commented 1 day ago

Thank you for your feedback