diff --git a/README.md b/README.md
index c3e61b17..edc6e874 100644
--- a/README.md
+++ b/README.md
@@ -28,6 +28,8 @@ npm install --save reactfire firebase
 yarn add reactfire firebase
 ```
 
+Depending on your targeted platforms you may need to install polyfills. The most commonly needed will be [globalThis](https://caniuse.com/#search=globalThis) and [Proxy](https://caniuse.com/#search=Proxy).
+
 - [**Quickstart**](./docs/quickstart.md)
 - [**Common Use Cases**](./docs/use.md)
 - [**API Reference**](./docs/reference.md)
@@ -40,12 +42,7 @@ Check out the
 ```jsx
 import React, { Component } from 'react';
 import { createRoot } from 'react-dom';
-import {
-  FirebaseAppProvider,
-  useFirestoreDocData,
-  useFirestore,
-  SuspenseWithPerf
-} from 'reactfire';
+import { FirebaseAppProvider, useFirestoreDocData, useFirestore, SuspenseWithPerf } from 'reactfire';
 
 const firebaseConfig = {
   /* Add your config from the Firebase Console */
@@ -70,10 +67,7 @@ function App() {
   return (
     <FirebaseAppProvider firebaseConfig={firebaseConfig}>
       <h1>🌯</h1>
-      <SuspenseWithPerf
-        fallback={<p>loading burrito status...</p>}
-        traceId={'load-burrito-status'}
-      >
+      <SuspenseWithPerf fallback={<p>loading burrito status...</p>} traceId={'load-burrito-status'}>
         <Burrito />
       </SuspenseWithPerf>
     </FirebaseAppProvider>
diff --git a/reactfire/database/index.tsx b/reactfire/database/index.tsx
index 77e43b5d..fd273d2f 100644
--- a/reactfire/database/index.tsx
+++ b/reactfire/database/index.tsx
@@ -1,30 +1,35 @@
 import { database } from 'firebase/app';
 import { list, object, QueryChange, listVal } from 'rxfire/database';
-import {
-  ReactFireOptions,
-  useObservable,
-  checkIdField,
-  checkStartWithValue
-} from '..';
+import { ReactFireOptions, useObservable, checkIdField, checkStartWithValue } from '..';
 
 import { Observable } from 'rxjs';
 import { map } from 'rxjs/operators';
 
+const CACHED_QUERIES = '_reactFireDatabaseCachedQueries';
+
+// Since we're side-effect free, we need to ensure our observableId cache is global
+const cachedQueries: Array<database.Query> = globalThis[CACHED_QUERIES] || [];
+
+if (!globalThis[CACHED_QUERIES]) {
+  globalThis[CACHED_QUERIES] = cachedQueries;
+}
+
+function getUniqueIdForDatabaseQuery(query: database.Query) {
+  const index = cachedQueries.findIndex(cachedQuery => cachedQuery.isEqual(query));
+  if (index > -1) {
+    return index;
+  }
+  return cachedQueries.push(query) - 1;
+}
+
 /**
  * Subscribe to a Realtime Database object
  *
  * @param ref - Reference to the DB object you want to listen to
  * @param options
  */
-export function useDatabaseObject<T = unknown>(
-  ref: database.Reference,
-  options?: ReactFireOptions<T>
-): QueryChange | T {
-  return useObservable(
-    object(ref),
-    `database:object:${ref.toString()}`,
-    options ? options.startWithValue : undefined
-  );
+export function useDatabaseObject<T = unknown>(ref: database.Reference, options?: ReactFireOptions<T>): QueryChange | T {
+  return useObservable(object(ref), `database:object:${ref.toString()}`, options ? options.startWithValue : undefined);
 }
 
 // ============================================================================
@@ -50,23 +55,9 @@ function changeToData(change: QueryChange, keyField?: string): {} {
 }
 // ============================================================================
 
-export function useDatabaseObjectData<T>(
-  ref: database.Reference,
-  options?: ReactFireOptions<T>
-): T {
+export function useDatabaseObjectData<T>(ref: database.Reference, options?: ReactFireOptions<T>): T {
   const idField = checkIdField(options);
-  return useObservable(
-    objectVal(ref, idField),
-    `database:objectVal:${ref.toString()}:idField=${idField}`,
-    checkStartWithValue(options)
-  );
-}
-
-// Realtime Database has an undocumented method
-// that helps us build a unique ID for the query
-// https://github.com/firebase/firebase-js-sdk/blob/aca99669dd8ed096f189578c47a56a8644ac62e6/packages/database/src/api/Query.ts#L601
-interface _QueryWithId extends database.Query {
-  queryIdentifier(): string;
+  return useObservable(objectVal(ref, idField), `database:objectVal:${ref.toString()}:idField=${idField}`, checkStartWithValue(options));
 }
 
 /**
@@ -79,23 +70,12 @@ export function useDatabaseList<T = { [key: string]: unknown }>(
   ref: database.Reference | database.Query,
   options?: ReactFireOptions<T[]>
 ): QueryChange[] | T[] {
-  const hash = `database:list:${ref.toString()}|${(ref as _QueryWithId).queryIdentifier()}`;
+  const hash = `database:list:${getUniqueIdForDatabaseQuery(ref)}`;
 
-  return useObservable(
-    list(ref),
-    hash,
-    options ? options.startWithValue : undefined
-  );
+  return useObservable(list(ref), hash, options ? options.startWithValue : undefined);
 }
 
-export function useDatabaseListData<T = { [key: string]: unknown }>(
-  ref: database.Reference | database.Query,
-  options?: ReactFireOptions<T[]>
-): T[] {
+export function useDatabaseListData<T = { [key: string]: unknown }>(ref: database.Reference | database.Query, options?: ReactFireOptions<T[]>): T[] {
   const idField = checkIdField(options);
-  return useObservable(
-    listVal(ref, idField),
-    `database:listVal:${ref.toString()}|${(ref as _QueryWithId).queryIdentifier()}:idField=${idField}`,
-    checkStartWithValue(options)
-  );
+  return useObservable(listVal(ref, idField), `database:listVal:${getUniqueIdForDatabaseQuery(ref)}:idField=${idField}`, checkStartWithValue(options));
 }
diff --git a/reactfire/firestore/index.tsx b/reactfire/firestore/index.tsx
index c5d0d8a8..62f32462 100644
--- a/reactfire/firestore/index.tsx
+++ b/reactfire/firestore/index.tsx
@@ -1,21 +1,27 @@
 import { firestore } from 'firebase/app';
-import {
-  collectionData,
-  doc,
-  docData,
-  fromCollectionRef
-} from 'rxfire/firestore';
-import {
-  preloadFirestore,
-  ReactFireOptions,
-  useObservable,
-  checkIdField,
-  checkStartWithValue
-} from '..';
+import { collectionData, doc, docData, fromCollectionRef } from 'rxfire/firestore';
+import { preloadFirestore, ReactFireOptions, useObservable, checkIdField, checkStartWithValue } from '..';
 import { preloadObservable } from '../useObservable';
 import { first } from 'rxjs/operators';
 import { useFirebaseApp } from '../firebaseApp';
 
+const CACHED_QUERIES = '_reactFireFirestoreQueryCache';
+
+// Since we're side-effect free, we need to ensure our observableId cache is global
+const cachedQueries: Array<firestore.Query> = globalThis[CACHED_QUERIES] || [];
+
+if (!globalThis[CACHED_QUERIES]) {
+  globalThis[CACHED_QUERIES] = cachedQueries;
+}
+
+function getUniqueIdForFirestoreQuery(query: firestore.Query) {
+  const index = cachedQueries.findIndex(cachedQuery => cachedQuery.isEqual(query));
+  if (index > -1) {
+    return index;
+  }
+  return cachedQueries.push(query) - 1;
+}
+
 // starts a request for a firestore doc.
 // imports the firestore SDK automatically
 // if it hasn't been imported yet.
@@ -23,18 +29,13 @@ import { useFirebaseApp } from '../firebaseApp';
 // there's a decent chance this gets called before the Firestore SDK
 // has been imported, so it takes a refProvider instead of a ref
 export function preloadFirestoreDoc(
-  refProvider: (
-    firestore: firebase.firestore.Firestore
-  ) => firestore.DocumentReference,
+  refProvider: (firestore: firebase.firestore.Firestore) => firestore.DocumentReference,
   options?: { firebaseApp?: firebase.app.App }
 ) {
   const firebaseApp = options?.firebaseApp || useFirebaseApp();
-  return preloadFirestore({firebaseApp}).then(firestore => {
+  return preloadFirestore({ firebaseApp }).then(firestore => {
     const ref = refProvider(firestore());
-    return preloadObservable(
-      doc(ref),
-      `firestore:doc:${firebaseApp.name}:${ref.path}`
-    );
+    return preloadObservable(doc(ref), `firestore:doc:${firebaseApp.name}:${ref.path}`);
   });
 }
 
@@ -44,15 +45,8 @@ export function preloadFirestoreDoc(
  * @param ref - Reference to the document you want to listen to
  * @param options
  */
-export function useFirestoreDoc<T = unknown>(
-  ref: firestore.DocumentReference,
-  options?: ReactFireOptions<T>
-): T extends {} ? T : firestore.DocumentSnapshot {
-  return useObservable(
-    doc(ref),
-    `firestore:doc:${ref.firestore.app.name}:${ref.path}`,
-    options ? options.startWithValue : undefined
-  );
+export function useFirestoreDoc<T = unknown>(ref: firestore.DocumentReference, options?: ReactFireOptions<T>): T extends {} ? T : firestore.DocumentSnapshot {
+  return useObservable(doc(ref), `firestore:doc:${ref.firestore.app.name}:${ref.path}`, options ? options.startWithValue : undefined);
 }
 
 /**
@@ -65,11 +59,7 @@ export function useFirestoreDocOnce<T = unknown>(
   ref: firestore.DocumentReference,
   options?: ReactFireOptions<T>
 ): T extends {} ? T : firestore.DocumentSnapshot {
-  return useObservable(
-    doc(ref).pipe(first()),
-    `firestore:docOnce:${ref.firestore.app.name}:${ref.path}`,
-    checkStartWithValue(options)
-  );
+  return useObservable(doc(ref).pipe(first()), `firestore:docOnce:${ref.firestore.app.name}:${ref.path}`, checkStartWithValue(options));
 }
 
 /**
@@ -78,16 +68,9 @@ export function useFirestoreDocOnce<T = unknown>(
  * @param ref - Reference to the document you want to listen to
  * @param options
  */
-export function useFirestoreDocData<T = unknown>(
-  ref: firestore.DocumentReference,
-  options?: ReactFireOptions<T>
-): T {
+export function useFirestoreDocData<T = unknown>(ref: firestore.DocumentReference, options?: ReactFireOptions<T>): T {
   const idField = checkIdField(options);
-  return useObservable(
-    docData(ref, idField),
-    `firestore:docData:${ref.firestore.app.name}:${ref.path}:idField=${idField}`,
-    checkStartWithValue(options)
-  );
+  return useObservable(docData(ref, idField), `firestore:docData:${ref.firestore.app.name}:${ref.path}:idField=${idField}`, checkStartWithValue(options));
 }
 
 /**
@@ -96,10 +79,7 @@ export function useFirestoreDocData<T = unknown>(
  * @param ref - Reference to the document you want to get
  * @param options
  */
-export function useFirestoreDocDataOnce<T = unknown>(
-  ref: firestore.DocumentReference,
-  options?: ReactFireOptions<T>
-): T {
+export function useFirestoreDocDataOnce<T = unknown>(ref: firestore.DocumentReference, options?: ReactFireOptions<T>): T {
   const idField = checkIdField(options);
   return useObservable(
     docData(ref, idField).pipe(first()),
@@ -118,29 +98,8 @@ export function useFirestoreCollection<T = { [key: string]: unknown }>(
   query: firestore.Query,
   options?: ReactFireOptions<T[]>
 ): T extends {} ? T[] : firestore.QuerySnapshot {
-  const queryId = `firestore:collection:${
-    query.firestore.app.name
-  }:${getHashFromFirestoreQuery(query)}`;
-
-  return useObservable(
-    fromCollectionRef(query),
-    queryId,
-    checkStartWithValue(options)
-  );
-}
-
-// The Firestore SDK has an undocumented _query
-// object that has a method to generate a hash for a query,
-// which we need for useObservable
-// https://github.com/firebase/firebase-js-sdk/blob/5beb23cd47312ffc415d3ce2ae309cc3a3fde39f/packages/firestore/src/core/query.ts#L221
-interface _QueryWithId extends firestore.Query {
-  _query: {
-    canonicalId(): string;
-  };
-}
-
-function getHashFromFirestoreQuery(query: firestore.Query) {
-  return (query as _QueryWithId)._query.canonicalId();
+  const queryId = `firestore:collection:${getUniqueIdForFirestoreQuery(query)}`;
+  return useObservable(fromCollectionRef(query), queryId, checkStartWithValue(options));
 }
 
 /**
@@ -149,18 +108,9 @@ function getHashFromFirestoreQuery(query: firestore.Query) {
  * @param ref - Reference to the collection you want to listen to
  * @param options
  */
-export function useFirestoreCollectionData<T = { [key: string]: unknown }>(
-  query: firestore.Query,
-  options?: ReactFireOptions<T[]>
-): T[] {
+export function useFirestoreCollectionData<T = { [key: string]: unknown }>(query: firestore.Query, options?: ReactFireOptions<T[]>): T[] {
   const idField = checkIdField(options);
-  const queryId = `firestore:collectionData:${
-    query.firestore.app.name
-  }:${getHashFromFirestoreQuery(query)}:idField=${idField}`;
+  const queryId = `firestore:collectionData:${getUniqueIdForFirestoreQuery(query)}:idField=${idField}`;
 
-  return useObservable(
-    collectionData(query, idField),
-    queryId,
-    checkStartWithValue(options)
-  );
+  return useObservable(collectionData(query, idField), queryId, checkStartWithValue(options));
 }
diff --git a/reactfire/jest.setup.js b/reactfire/jest.setup.js
new file mode 100644
index 00000000..cb7437ec
--- /dev/null
+++ b/reactfire/jest.setup.js
@@ -0,0 +1 @@
+global.globalThis = require('globalthis')();
diff --git a/reactfire/package.json b/reactfire/package.json
index cbc538e9..6837ba6c 100644
--- a/reactfire/package.json
+++ b/reactfire/package.json
@@ -44,9 +44,15 @@
     "babel-jest": "^24.9.0",
     "firebase-functions-test": "^0.1.6",
     "firebase-tools": "^7.1.0",
+    "globalthis": "^1.0.1",
     "jest": "~24.9.0",
     "react-test-renderer": "^16.9.0",
     "rollup": "^1.26.3",
     "typescript": "^3.4.5"
+  },
+  "jest": {
+    "setupFiles": [
+      "../jest.setup.js"
+    ]
   }
 }
diff --git a/reactfire/useObservable/index.ts b/reactfire/useObservable/index.ts
index 45e3b326..baf9c75c 100644
--- a/reactfire/useObservable/index.ts
+++ b/reactfire/useObservable/index.ts
@@ -2,18 +2,11 @@ import * as React from 'react';
 import { Observable } from 'rxjs';
 import { SuspenseSubject } from './SuspenseSubject';
 
-const globalThis = function() {
-  if (typeof self !== 'undefined') { return self; }
-  if (typeof window !== 'undefined') { return window; }
-  if (typeof global !== 'undefined') { return global; }
-  throw new Error('unable to locate global object');
-}();
-
 const PRELOADED_OBSERVABLES = '_reactFirePreloadedObservables';
 const DEFAULT_TIMEOUT = 30_000;
 
 // Since we're side-effect free, we need to ensure our observable cache is global
-const preloadedObservables = globalThis[PRELOADED_OBSERVABLES] || new Map<string, SuspenseSubject<unknown>>();
+const preloadedObservables: Map<string, SuspenseSubject<unknown>> = globalThis[PRELOADED_OBSERVABLES] || new Map();
 
 if (!globalThis[PRELOADED_OBSERVABLES]) {
   globalThis[PRELOADED_OBSERVABLES] = preloadedObservables;
@@ -32,12 +25,7 @@ export function preloadObservable<T>(source: Observable<T>, id: string) {
   }
 }
 
-export function useObservable<T>(
-  source: Observable<T | any>,
-  observableId: string,
-  startWithValue?: T | any,
-  deps: React.DependencyList = [observableId]
-): T {
+export function useObservable<T>(source: Observable<T | any>, observableId: string, startWithValue?: T | any, deps: React.DependencyList = [observableId]): T {
   if (!observableId) {
     throw new Error('cannot call useObservable without an observableId');
   }
@@ -45,9 +33,7 @@ export function useObservable<T>(
   if (!observable.hasValue && !startWithValue) {
     throw observable.firstEmission;
   }
-  const [latest, setValue] = React.useState(() =>
-    observable.hasValue ? observable.value : startWithValue
-  );
+  const [latest, setValue] = React.useState(() => (observable.hasValue ? observable.value : startWithValue));
   React.useEffect(() => {
     const subscription = observable.subscribe(
       v => setValue(() => v),
diff --git a/yarn.lock b/yarn.lock
index 0f014d33..c245514b 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6137,6 +6137,13 @@ globals@^12.1.0:
   dependencies:
     type-fest "^0.8.1"
 
+globalthis@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/globalthis/-/globalthis-1.0.1.tgz#40116f5d9c071f9e8fb0037654df1ab3a83b7ef9"
+  integrity sha512-mJPRTc/P39NH/iNG4mXa9aIhNymaQikTrnspeCa2ZuJ+mH2QN/rXwtX3XwKrHqWgUQFbNZKtHM105aHzJalElw==
+  dependencies:
+    define-properties "^1.1.3"
+
 globby@8.0.2:
   version "8.0.2"
   resolved "https://registry.yarnpkg.com/globby/-/globby-8.0.2.tgz#5697619ccd95c5275dbb2d6faa42087c1a941d8d"