Precision not respected for decimals in struct

[prayansh]

Hi! I am using the databricks-sql-go library in my application and seeing this weird behaviour when querying decimal columns. I am using CAST(... AS DECIMAL(5, 2)) to get my desired precision and it works for DECIMAL columns but when I do the same for values inside structs, the precision does not apply.

For example in this sql

SELECT
    '1' AS id,
    19.99 as test_decimal,
    named_struct('col1', 'Field1', 'col2', 19.99) as arr,
    CAST(19.99 AS DECIMAL(5, 2)) as test_decimal2,
    named_struct('col1', 'Field1', 'col2', CAST(19.99 AS DECIMAL(5, 2))) as arr2;

Heres a look at the sql row in debug mode Note that the decimal value in both structs is 19.990000000000002

With this sql I am querying the decimal value of 19.99 in different ways and I was expecting CAST(19.99 AS DECIMAL(5, 2) to be respected but instead I still get 19.990000000000002

Is there a better way to do this? Is this an issue with the driver and are there any plans to fix this on the driver side?

[JamesVorder]

Interesting. I was able to reproduce with the following code:

package main

import (
	"context"
	"database/sql"
	"fmt"

	_ "github.com/databricks/databricks-sql-go"
)

func main() {
	db, err := sql.Open("databricks", "token:*****@*****:443/sql/1.0/warehouses/*****")
	if err != nil {
		panic(err)
	}
	defer db.Close()

	row := db.QueryRowContext(context.Background(), `SELECT '1' AS id,
	19.99 as test_decimal,
	named_struct('col1', 'Field1', 'col2', 19.99) as arr,
	CAST(19.99 AS DECIMAL(5, 2)) as test_decimal2,
	named_struct('col1', 'Field1', 'col2', CAST(19.99 AS DECIMAL(5, 2))) as arr2;`)
	var id string
	var testDecimal float64
	var arr any
	var testDecimal2 float64
	var arr2 any
	err = row.Scan(&id, &testDecimal, &arr, &testDecimal2, &arr2)
	if err != nil {
		panic(err)
	}
	// Set a breakpoint on the next line to inspect variables in your debugger
	fmt.Println(id, testDecimal, arr, testDecimal2, arr2)
}