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https://issues.apache.org/jira/browse/SPARK-26841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16843509#comment-16843509
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Richard Yu edited comment on SPARK-26841 at 5/19/19 5:53 PM:
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[~Bartalos] Could you expain what use cases there are for supporting these
queries? It would be helpful if you could provide an example of how a "historic
snapshot" of the Kafka table might be useful to the client.
was (Author: yohan123):
[~Bartalos] Could you expain what use cases there are for supporting these
queries? It would be helpful if you could provide an example where a "historic
snapshot" might be necessary.
> Timestamp pushdown on Kafka table
> ---------------------------------
>
> Key: SPARK-26841
> URL: https://issues.apache.org/jira/browse/SPARK-26841
> Project: Spark
> Issue Type: Improvement
> Components: Input/Output
> Affects Versions: 2.4.0
> Reporter: Tomas Bartalos
> Priority: Major
> Labels: Kafka, pushdown, timestamp
>
> As a Spark user I'd like to have fast queries on Kafka table restricted by
> timestamp.
> I'd like to have quick answers on questions like:
> * What was inserted to Kafka in past x minutes
> * What was inserted to Kafka in specified time range
> Example:
> {quote}select * from kafka_table where timestamp >
> from_unixtime(unix_timestamp() - 5 * 60, "YYYY-MM-dd HH:mm:ss")
> select * from kafka_table where timestamp > $from_time and timestamp <
> $end_time
> {quote}
> Currently timestamp restrictions are not pushdown to KafkaRelation and
> querying by timestamp on a large Kafka topic takes forever to complete.
> *Technical solution*
> Technically its possible to retrieve Kafka's offsets by provided timestamp
> with org.apache.kafka.clients.consumer.Consumer#offsetsForTimes(..) method.
> Afterwards we can query Kafka topic by retrieved timestamp ranges.
> Querying by timestamp range is already implemented so this change should have
> minor impact.
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