140378476 opened a new issue #2132:
URL: https://github.com/apache/iotdb/issues/2132
**Describe the bug**
I got clearly incorrect results when retrieving data using method
`getFloat`.
Addtionally, I can get a String representation of the data, which is highly
inprecise and requires extra parsing.
**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. Retrieve data using JDBC: (mostly copied from the user guide and
converted to Kotlin)
```
fun getConnection(): Connection? {
// JDBC driver name and database URL
val driver = "org.apache.iotdb.jdbc.IoTDBDriver"
val url = "jdbc:iotdb://127.0.0.1:6667/"
// Database credentials
val username = "root"
val password = "root"
var connection: Connection? = null
try {
Class.forName(driver)
connection = DriverManager.getConnection(url, username, password)
} catch (e: ClassNotFoundException) {
e.printStackTrace()
} catch (e: SQLException) {
e.printStackTrace()
}
return connection
}
fun select(){
val connection = getConnection()
if (connection == null) {
println("get connection defeat")
return
}
val statement: Statement = connection.createStatement()
statement.execute("SELECT d from root.test")
val rs = statement.resultSet
rs.next()
println("String:")
println(rs.getString(2))
println("Float:")
println(rs.getFloat(2))
}
```
4. The output is:
```
String:
1.23
Float:
1.06728262E9
```
I got the approximately correct result from `getString()` but incorrect
result from `getFloat()`.
**Expected behavior**
I should get a precise float result from `getFloat()`.
**Desktop (please complete the following information):**
- OS: [e.g. iOS]
- Browser [e.g. chrome, safari]
- Version [e.g. 22]
**Additional context**
The inplementation in `IoTDBRpcDataSet.java` shows that it just converts
the bytes to float in the method, while the bytes are actually in the format
of String.
A further dig into the source code shows that all data are in the format of
String except the timestamp.
Therefore, a simple fix is not possible because the issue is that the raw
data transferred from the
database is in the format of String.
This can cause precision loss and significant performance issue(extra
parsing and formatting, more transfer cost).
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