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Richard Yu commented on KAFKA-4499: ----------------------------------- Some information is currently lacking when it comes to fetchAll() as the keys associated with the timeFrom and timeTo parameters is missing, so I decided to use a substitute. If permissible, a TreeMap or HashMap can be added so that the timestamps and there corresponding keys (byte arrays) could be recorded and retrieved. > Add "getAllKeys" API for querying windowed KTable stores > -------------------------------------------------------- > > Key: KAFKA-4499 > URL: https://issues.apache.org/jira/browse/KAFKA-4499 > Project: Kafka > Issue Type: Improvement > Components: streams > Reporter: Matthias J. Sax > Labels: needs-kip > Attachments: 4499-CachingWindowStore-v1.patch > > > Currently, both {{KTable}} and windowed-{{KTable}} stores can be queried via > IQ feature. While {{ReadOnlyKeyValueStore}} (for {{KTable}} stores) provide > method {{all()}} to scan the whole store (ie, returns an iterator over all > stored key-value pairs), there is no similar API for {{ReadOnlyWindowStore}} > (for windowed-{{KTable}} stores). > This limits the usage of a windowed store, because the user needs to know > what keys are stored in order the query it. It would be useful to provide > possible APIs like this (only a rough sketch): > - {{keys()}} returns all keys available in the store (maybe together with > available time ranges) > - {{all(long timeFrom, long timeTo)}} that returns all window for a specific > time range > - {{allLatest()}} that returns the latest window for each key > Because this feature would require to scan multiple segments (ie, RockDB > instances) it would be quite inefficient with current store design. Thus, > this feature also required to redesign the underlying window store itself. > Because this is a major change, a KIP > (https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Improvement+Proposals) > is required. The KIP should cover the actual API design as well as the store > refactoring. -- This message was sent by Atlassian JIRA (v6.4.14#64029)