So I have this app using Ionic React and Cloud Firestore as the Database. Mostly I use these codes to retrieve data:

```
const [teacher, setTeacher] = useState('');
const history = useHistory();
const [users, setUsers] = useState([{}]);

async function obtainData() {
    const querySnapshot = db.collection('TEACHER_DATA').where('email', '==', Cookies.get('email'));
    const awaitSnapshot = await querySnapshot.get();
    const data = awaitSnapshot.docs.map(doc => doc.data().name);
    setTeacher(String(data));

    const querySnapshot2 = db.collection('CLASS').where('class_teacher', '==', teacher);
    const awaitSnapshot2 = await querySnapshot2.get();
    const data2 = awaitSnapshot2.docs.map(doc => doc.data());
    setUsers(data2);
}

obtainData();

return (
    <div>{
        users.map((value: any, index) => (
                <IonCard key={index} onClick={() => {
                    Cookies2.set('id', value.student_id);
                    history.push({
                        pathname: '/Student_biodata',
                        state: value.student_id
                    })
                  }} class="students">
                      <IonCardTitle>
                          {value.class_student}
                      </IonCardTitle>
                    {value.branch}
                    <IonCard id="mini-picture">
                        <IonImg src={'/assets/propic/' + value.student_id + '.jpg'}></IonImg>
                    </IonCard>

                </IonCard>
            ))}
    </div>
);

```

This code shows the data I needed. However, when I checked the Firestore Usage, in 15 minutes it already has 6K reads. This is not suitable if someday the user number is increasing. My app will reach the daily limit quota in no time. The documents in my Firestore project is less than 30.

**Is there any solution for me to reduce the read in Firestore? Is there any example to make a better structure in NoSQL Firestore to reduce the read?**
I've watched the tutorial videos from Firebase about Firestore yet I still don't get it.