Float value changes after writing to realm even for integer part of the complete number

[gauravbordoloi]

How frequently does the bug occur?

Always

Description

Float value changes after writing to realm even for integer part of the complete number

import Realm from "realm"

class TData extends Realm.Object {
    static schema = {
        name: "CategoryModel",
        properties: {
            b: "string",
            a: "double",
            c: "float",
        },
        primaryKey: 'b',
    }
}

const db = {
    //path: DB_PATH,
    schema: [TData]
}

let realm = await Realm.open(db);

let p = `${Date.now()}`

let v = 1628899821

realm.write(() => {
    realm.create(TData, { a: v, c: v, b: p })
})

console.log(realm.objectForPrimaryKey(TData, p).toJSON())![image](https://github.com/realm/realm-js/assets/23193185/2c6a3b80-86dc-45fd-8990-3a05104f5ad3)

Stacktrace & log output

No response

Can you reproduce the bug?

Always

Reproduction Steps

No response

Version

12.3.1

What services are you using?

Local Database only

Are you using encryption?

No

Platform OS and version(s)

Windows 11

Build environment

No response

Cocoapods version

No response

[kneth]

@gauravbordoloi

Thank you for reporting. We (JS + Kotlin) need to investigate why float is behaving this time.

[gauravbordoloi]

@kneth This hit us on a production environment. Any support on quick will be really helpful else I have to migrate the keys to double. Double is working fine.

[gauravbordoloi]

Hi @kneth Any update on this?

[nirinchev]

Float values cannot precisely represent integers above ~16 million. This is because a 32-bit float uses 24 bits for the mantissa and 8 bits for the exponent. If you need to represent large integers, you'd need to either use an int, double, or Decimal128. You can find more technical information about this in the answers of this SO question.