Clear the lastLimboFreeSnapshot version on existence filter mismatch

Author: schmidt-sebastian

packages/firestore/src/local/local_store_impl.ts

@@ -501,24 +501,32 @@ export function localStoreApplyRemoteEventToLocalCache(
             })
         );
 
-        const resumeToken = change.resumeToken;
-        // Update the resume token if the change includes one.
-        if (resumeToken.approximateByteSize() > 0) {
-          const newTargetData = oldTargetData
-            .withResumeToken(resumeToken, remoteVersion)
-            .withSequenceNumber(txn.currentSequenceNumber);
-          newTargetDataByTargetMap = newTargetDataByTargetMap.insert(
-            targetId,
-            newTargetData
+        let newTargetData = oldTargetData.withSequenceNumber(
+          txn.currentSequenceNumber
+        );
+        if (remoteEvent.targetMismatches.has(targetId)) {
+          newTargetData = newTargetData.withResumeToken(
+            ByteString.EMPTY_BYTE_STRING,
+            SnapshotVersion.min()
+          );
+        } else if (change.resumeToken.approximateByteSize() > 0) {
+          newTargetData = newTargetData.withResumeToken(
+            change.resumeToken,
+            remoteVersion
           );
+        }
 
-          // Update the target data if there are target changes (or if
-          // sufficient time has passed since the last update).
-          if (shouldPersistTargetData(oldTargetData, newTargetData, change)) {
-            promises.push(
-              localStoreImpl.targetCache.updateTargetData(txn, newTargetData)
-            );
-          }
+        newTargetDataByTargetMap = newTargetDataByTargetMap.insert(
+          targetId,
+          newTargetData
+        );
+
+        // Update the target data if there are target changes (or if
+        // sufficient time has passed since the last update).
+        if (shouldPersistTargetData(oldTargetData, newTargetData, change)) {
+          promises.push(
+            localStoreImpl.targetCache.updateTargetData(txn, newTargetData)
+          );
         }
       });
 
@@ -675,11 +683,6 @@ function shouldPersistTargetData(
   newTargetData: TargetData,
   change: TargetChange
 ): boolean {
-  hardAssert(
-    newTargetData.resumeToken.approximateByteSize() > 0,
-    'Attempted to persist target data with no resume token'
-  );
-
   // Always persist target data if we don't already have a resume token.
   if (oldTargetData.resumeToken.approximateByteSize() === 0) {
     return true;

packages/firestore/test/unit/specs/existence_filter_spec.test.ts

@@ -211,4 +211,29 @@ describeSpec('Existence Filters:', [], () => {
         })
     );
   });
+
+  specTest(
+    'Existence filter mismatch invalidates index-free query',
+    ['durable-persistence'],
+    () => {
+      // This is a test for https://github.com/firebase/firebase-android-sdk/issues/3249
+      // In this particular scenario, the user received an existence filter
+      // mismatch, but the SDK only cleared the target-to-document mapping and
+      // not the lastLimboFreeSnapshot version. This caused the SDK to resume
+      // the query but not include old documents.
+      const query1 = query('collection');
+      const doc1 = doc('collection/1', 1000, { v: 1 });
+      const doc2 = doc('collection/2', 1000, { v: 2 });
+      return spec()
+        .userListens(query1)
+        .watchAcksFull(query1, 1000, doc1, doc2)
+        .expectEvents(query1, { added: [doc1, doc2] })
+        .watchFilters([query1], doc1.key) // doc2 was deleted
+        .watchSnapshots(2000)
+        .expectEvents(query1, { fromCache: true })
+        .restart()
+        .userListens(query1)
+        .expectEvents(query1, { added: [doc1, doc2], fromCache: true });
+    }
+  );
 });