[GitHub] [kafka] vamossagar12 commented on a change in pull request #10052: KAFKA-12289: Adding test cases for prefix scan in InMemoryKeyValueStore

[GitBox <gi...@apache.org>]

vamossagar12 commented on a change in pull request #10052:
URL: https://github.com/apache/kafka/pull/10052#discussion_r570171267



##########
File path: streams/src/test/java/org/apache/kafka/streams/state/internals/InMemoryKeyValueStoreTest.java
##########
@@ -60,4 +67,22 @@ public void shouldRemoveKeysWithNullValues() {
 
         assertThat(store.get(0), nullValue());
     }
+
+
+    @Test
+    public void shouldReturnKeysWithGivenPrefix(){
+        store = createKeyValueStore(driver.context());
+        final String value = "value";
+        final List<KeyValue<Integer, String>> entries = new ArrayList<>();
+        entries.add(new KeyValue<>(1, value));
+        entries.add(new KeyValue<>(2, value));
+        entries.add(new KeyValue<>(11, value));
+        entries.add(new KeyValue<>(13, value));
+
+        store.putAll(entries);
+        final KeyValueIterator<Integer, String> keysWithPrefix = store.prefixScan(1, new IntegerSerializer());

Review comment:
       @cadonna I found something interesting here. As you can see this creates a state store with Integer prefix. Now when I run prefixScan, I get only 1 from the iterator even though we have 11 and 13 as the keys. This is because in prefixScan, we do this: `final Bytes to = Bytes.increment(from);` which sets `to` to 2.
   Because of that, it doesn't return all the keys. 
   Question is, with prefix Scan we are primarily focussing on lexicographically next key which has the same prefix. That way, 11 should be returned. But with the way it has been implemented for this store, it won't work. 




----------------------------------------------------------------
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

For queries about this service, please contact Infrastructure at:
users@infra.apache.org