Race condition in valueChanges()

Race condition happening in valueChanges() of doc [subscribe keeps firing with no data change in document]. The issue is happening in angular prod build, Dev build works fine. Tested downgrading the package to AngularFire v6.0.5, the issue is not replicable.

Version info

**Angular: 10.2.3

**Firebase:8.2.1

**AngularFire:6.1.4

How to reproduce these conditions

sample code

this.getString()
      .pipe(switchMap((docName) => {
        if (docName !== '') {
          return this.angularFireStore.collection(eColName.PublicCol).doc(docName).valueChanges();
        }
      })).pipe(filter(val => val !== null))
      .subscribe(
        (publicDocData) => {
          this.publicData.next(publicDocDataa);
        }
      );

Debug output

NA

Expected behavior

Subscribe method should execute on start and on doc change

Actual behavior

Subscribe method executed like while loop without any end

Details I’m not sure is relevant: Tsconfig: “module”: “es2020”, “target”: “ES2015”, Angular dev and Prod build diff. optimization & buildOptimizer are true in prod rest are same

[jamesdaniels]

I bet this has to do with metadata changes, I fixed a bug which meant they weren’t getting emitted on snapshotChanges… perhaps I need to add a distinctUntilChanged(... /* deep eq check */) on the return from valueChanges(). Honestly I usually use snapshotChanges myself so I’m use to seeing all these extra emissions. I’ll look into this.

FWIW that might be a work around for now.

[jamesdaniels]

Closing as some of this should be addressed in v7, others are just how the library works, developers should use distinctUntilChanged to reduce down change detection fires to changes that they care about