🔥 Error "firestore/failed-precondition" when filtering a collection group query in FireStore

[appukuttan-shailesh]

Issue

I have a database structure as follows (simplified for purposes of this question):

Collection: item_A
    -> Document: params = {someParameter: "value"}
    -> Document: user_01
        -> Sub-collection: orders_item_A
            -> Document: order_AA = {type: "A1", address: {pincode: "000000", city:"Paris"}
            -> Document: order_AB = {type: "A2", address: {pincode: "111111", city:"London"}
            ...
    -> Document: user_02
        -> Sub-collection: orders_item_A
            -> Document: order_AC = {type: "A1", address: {pincode: "222222", city:"Berlin"}
            -> Document: order_AD = {type: "A1", address: {pincode: "333333", city:"Paris"}
            ...

I am using a collection group query to retrieve all the orders under "item_A" (across all users). I am able to get this to work via:

let orders = [];
await firestore()
    .collectionGroup("orders_item_A")
    .get()
    .then(function (querySnapshot) {
        querySnapshot.forEach(function (doc) {
            console.log(doc.id, ' => ', doc.data());
            orders.push(doc.data());
        });
    })

But now I need to refine the above to be able to filter for orders from specific cities (e.g. Paris). So I tried adding a 'where' clause as follows:

let orders = [];
await firestore()
    .collectionGroup("orders_item_A")
    .where("address.city", "==", "Paris")
    .get()
    .then(function (querySnapshot) {
        querySnapshot.forEach(function (doc) {
            console.log(doc.id, ' => ', doc.data());
            orders.push(doc.data());
        });
    })

But this fails, and I get the following message:

[Error: [firestore/failed-precondition] Operation was rejected because the system is not in a state required for the operation's execution. Ensure your query has been indexed via the Firebase console.]

I have already set up a composite index on my FireStore database with the following details:

Collection ID = orders_item_A
Fields indexed = address.city Ascending type Ascending
Status = Enabled

I am not sure what I am doing incorrectly. I wondered if the problem is with using an object property within the 'where' clause (which should not be a problem I believe). So I also tested with a simpler query such as:

.where("type", "==", "A1")

But this too failed. What am I doing wrong?

I tried to find the "link" to create the composite index directly via error message but I just cannot locate this in my logs.

I tried the following (based on discussion here):

• adb logcat (this is expected to have contained the error message and link)
• react-native log-android (which is expected not to contain the url, but still tried)

But in both these places I simply find the same error message I mentioned earlier.
I can find nothing with the tag RNFSCollectionReference or anything else that helps.

On doing adb logcat -s RNFSCollectionReference I simply get (as mentioned by @tiendn here):

---

Project Files

Javascript

Click To Expand

package.json:

"react": "16.11.0",
"react-native": "0.62.2",
"@react-native-firebase/app": "^7.0.1",
"@react-native-firebase/auth": "^6.7.1",
"@react-native-firebase/firestore": "^7.0.1",

# N/A

firebase.json for react-native-firebase v6:

# N/A

iOS

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ios/Podfile:

• I'm not using Pods
• I'm using Pods and my Podfile looks like:

# N/A

AppDelegate.m:

// N/A

---

Android

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Have you converted to AndroidX?

• my application is an AndroidX application?
• I am using android/gradle.settings jetifier=true for Android compatibility?
• I am using the NPM package jetifier for react-native compatibility?

android/build.gradle:

// N/A

android/app/build.gradle:

// N/A

android/settings.gradle:

// N/A

MainApplication.java:

// N/A

AndroidManifest.xml:

<!-- N/A -->

---

Environment

Click To Expand

react-native info output:

 OUTPUT GOES HERE

• Platform that you're experiencing the issue on:
  • iOS
  • Android
  • iOS but have not tested behavior on Android
  • Android but have not tested behavior on iOS
  • Both
• react-native-firebase version you're using that has this issue:
  "@react-native-firebase/app": "^7.0.1",
  "@react-native-firebase/auth": "^6.7.1",
  "@react-native-firebase/firestore": "^7.0.1",
• Firebase module(s) you're using that has the issue:
  • e.g. Instance ID
• Are you using TypeScript?
  • N

---

• 👉 Check out React Native Firebase and Invertase on Twitter for updates on the library.

[appukuttan-shailesh]

I figured out the problem. My mistake was apparently in having made a "Composite" index (as I mentioned in the question) as it was the opening page on clicking "Indexes". I should have made a "Single field" index:

After deleting my existing composite index, I made a new "single field" index with details as:

Click 'Next' and on the next screen, "enable" one of the options under 'Collection group scope' (I chose Ascending):

It is important to do the above, or else the query will not work. And then everything worked as expected, with my original code:

let orders = []; await firestore() .collectionGroup("orders_item_A") .where("address.city", "==", "Paris") .get() .then(function (querySnapshot) { querySnapshot.forEach(function (doc) { console.log(doc.id, ' => ', doc.data()); orders.push(doc.data()); }); })

Note: If you happen to delete a particular "index", it takes some time (upto 10 minutes on some occasions) to be ready. During this period you will get an error if trying to create an index for the same entry. So wait, and try again after some time.

[CrossBread]

@appukuttan-shailesh thanks for documenting this, I was questioning my sanity. I trusted the "Just run the query and click the URL if one pops up" advice rather than creating my Collection Group Queries up front weeks ago. Now I've burned half a day finally realizing that the reason the query was throwing an error was the missing index, but like you, no URL was in the message, just the error.

[chavdardonchev]

@appukuttan-shailesh thanks for documenting this, I was questioning my sanity. I trusted the "Just run the query and click the URL if one pops up" advice rather than creating my Collection Group Queries up front weeks ago. Now I've burned half a day finally realizing that the reason the query was throwing an error was the missing index, but like you, no URL was in the message, just the error.

If you put your query in a Try/Catch you will not get the link. Just simple "failed-precondition".
I removed the try/catch and the exception thrown together with the link.

[lipob]

The onSnapshot function accepts three arguments. The third argument is an onError callback.

You can get the link to create the index by using the third argument to print the error in the console.

An example:

const unsusbcribe = onSnapshot(query, (querySnapshot) => {
      const entities: Entity[] = []

      querySnapshot.forEach(doc => {
        entities.push(doc.data() as Entity);
      });

      setEntities(entities);
    }, (error) => console.error(error));

[kitfit-dave]

I also don't get the link, either by catching the exception or just letting it be unhandled. It was only experience with that type of error that led me to realise that I needed to add an index.

Where is the normally helpful error message with he create index link in it for this case?

[ohld]

I just had the same issue.

What I've actually tried to do:

• get subcollection documents
• filtered by a key value

What the issue actually mean:

• you have not created a "Single field" index (exemption)
• with a "query scope" set to Collection group

Note that if you may filter by different fields (sets of fields) you need to make sure you have indexes for all of them.

[mikehardy]

If you run it the app with the query that is missing an index on an android device or emulator and are running adb logcat, do you see a message with an URL to create the index? Just curious - I know if you do the query in the firebase-js-sdk it pops up in console.log at least

[ohld]

@mikehardy Actually I received an URL to create an index... but only a composite one. I got no links regards adding "single field" indexes, just a FAILED_PRECONDITION 9 error. I'm using firebase cloud functions, this error appeared only on deployed functions. If I run them locally I have no issues.

[mikehardy]

Interesting - I've seen the same with cloud functions - that's something you might file upstream with the firebase official site as cloud functions aren't under our control at all and if there is a missing index it would be good to know, composite or single index, yes. The firebase-tools local emulator never appears to care about indexes so I don't find out about them myself until I deploy to my dev or qa backends

[50an6xy06r6n]

We have also started to run into an issue where we get a FAILED_PRECONDITION error with no further details in the Node Admin SDK

[TomTasche]

We have also started to run into an issue where we get a FAILED_PRECONDITION error with no further details in the Node Admin SDK

That's a known issue, follow this thread for updates: googleapis/nodejs-firestore#1866

(Adding this here because it's one of the top Google search results, so more people are likely to come across this thread)