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Posted to reviews@iotdb.apache.org by GitBox <gi...@apache.org> on 2020/11/26 15:12:25 UTC
[GitHub] [iotdb] 140378476 opened a new issue #2131: Precision lost and incompatible precisions between select and select last.
140378476 opened a new issue #2131:
URL: https://github.com/apache/iotdb/issues/2131
**Describe the bug**
1. I can not get precise result of float values using `select` query.
2. When executing `select` and `select last`, I got float values in different precisions.
**To Reproduce**
Steps to reproduce the behavior:
1. Create timeseries: ` CREATE TIMESERIES root.t.d WITH DATATYPE=FLOAT, ENCODING=RLE`
2. Insert data: `INSERT INTO root.t(timestamp,d) VALUES(1,1.23456789)`
3. Select data: `SELECT * FROM root.t`, the returned value is `1.23`.
4. Select data using last: ` SELECT LAST * FROM root.t`, the returned value is `1.2345679`.
**Expected behavior**
It should return at least the precise float value instead of an approximate one.
The result is expected to at least be the same as the returned value using select last.
**Screenshots**
**Desktop (please complete the following information):**
- OS: Windows10
- Version iotdb 0.10.1
**Additional context**
No
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[GitHub] [iotdb] HTHou commented on issue #2131: Precision loss and incompatible precisions between select and select last.
Posted by GitBox <gi...@apache.org>.
HTHou commented on issue #2131:
URL: https://github.com/apache/iotdb/issues/2131#issuecomment-734380751
Hi, I think `RLE` is not a good choice for high precision. If you looking for high precision, better to use `GORILLA` instead.
Please see this doc on website for more information of the encoding precision.
https://iotdb.apache.org/UserGuide/Master/Concept/Encoding.html
The reason why `select last` doesn't loss precision is the result is cached when the data insert. :)
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[GitHub] [iotdb] HTHou edited a comment on issue #2131: Precision loss and incompatible precisions between select and select last.
Posted by GitBox <gi...@apache.org>.
HTHou edited a comment on issue #2131:
URL: https://github.com/apache/iotdb/issues/2131#issuecomment-734380751
Hi, I think `RLE` is not a good choice for high precision. If you looking for high precision, better to use `GORILLA` instead.
Please see this doc on website for more information of the encoding precision.
https://iotdb.apache.org/UserGuide/Master/Concept/Encoding.html
The reason why `select last` doesn't loss precision is the query result is cached when the data insert. :)
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[GitHub] [iotdb] 140378476 closed issue #2131: Precision loss and incompatible precisions between select and select last.
Posted by GitBox <gi...@apache.org>.
140378476 closed issue #2131:
URL: https://github.com/apache/iotdb/issues/2131
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