vamossagar12 commented on a change in pull request #10052:
URL: https://github.com/apache/kafka/pull/10052#discussion_r575374620
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File path:
streams/src/test/java/org/apache/kafka/streams/state/internals/InMemoryKeyValueStoreTest.java
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@@ -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 was thinking about this today and the question that I have
is what exactly does a prefix scan mean for numeric keys. For the way we have
implemented, it will work even for numeric keys if we can retrieve the keys in
Lexicographical manner.
So, if the prefix is `1` and post increment, it becomes `2`, then the range
in which I need to search becomes (1,2]. If my map has 1,2,11,13 then I should
be able to fetch 1,11,13 as those come before 2 lexicographically. But when I
test the underlying map from my test case, it returns 1,2,11,13 and that is why
the range is failing.
In the test class, the KV store being created has Integer keys, but the
underlying map still uses a lexicographically map. So, ideally, it should have
retured keys lexicographically.
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