jeqo commented on a change in pull request #9138:
URL: https://github.com/apache/kafka/pull/9138#discussion_r482160859
##########
File path:
streams/src/main/java/org/apache/kafka/streams/state/ReadOnlyWindowStore.java
##########
@@ -136,34 +174,64 @@
* <p>
* This iterator must be closed after use.
*
- * @param from the first key in the range
- * @param to the last key in the range
- * @param fromTime time range start (inclusive)
- * @param toTime time range end (inclusive)
- * @return an iterator over windowed key-value pairs {@code <Windowed<K>,
value>}
+ * @param from the first key in the range
+ * @param to the last key in the range
+ * @param timeFrom time range start (inclusive), where iteration starts.
+ * @param timeTo time range end (inclusive), where iteration ends.
+ * @return an iterator over windowed key-value pairs {@code <Windowed<K>,
value>}, from beginning to end of time.
* @throws InvalidStateStoreException if the store is not initialized
- * @throws NullPointerException If {@code null} is used for any key.
- * @throws IllegalArgumentException if duration is negative or can't be
represented as {@code long milliseconds}
+ * @throws NullPointerException If {@code null} is used for any key.
+ * @throws IllegalArgumentException if duration is negative or can't be
represented as {@code long milliseconds}
*/
- KeyValueIterator<Windowed<K>, V> fetch(K from, K to, Instant fromTime,
Instant toTime)
+ KeyValueIterator<Windowed<K>, V> fetch(K from, K to, Instant timeFrom,
Instant timeTo)
throws IllegalArgumentException;
/**
- * Gets all the key-value pairs in the existing windows.
- *
- * @return an iterator over windowed key-value pairs {@code <Windowed<K>,
value>}
- * @throws InvalidStateStoreException if the store is not initialized
- */
+ * Get all the key-value pairs in the given key range and time range from
all the existing windows
+ * in backward order with respect to time (from end to beginning of time).
+ * <p>
+ * This iterator must be closed after use.
+ *
+ * @param from the first key in the range
+ * @param to the last key in the range
+ * @param timeFrom time range start (inclusive), where iteration ends.
+ * @param timeTo time range end (inclusive), where iteration starts.
+ * @return an iterator over windowed key-value pairs {@code <Windowed<K>,
value>}, from end to beginning of time.
+ * @throws InvalidStateStoreException if the store is not initialized
+ * @throws NullPointerException If {@code null} is used for any key.
+ * @throws IllegalArgumentException if duration is negative or can't be
represented as {@code long milliseconds}
+ */
+ KeyValueIterator<Windowed<K>, V> backwardFetch(K from, K to, Instant
timeFrom, Instant timeTo)
Review comment:
https://github.com/apache/kafka/pull/9137#discussion_r468852245 old
discussion for context.
@guozhangwang is this scenario only possible with composite stores? or are
there other implementations where this is an alternative path?
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