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https://issues.apache.org/jira/browse/SPARK-26841?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16849454#comment-16849454
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Tomas Bartalos commented on SPARK-26841:
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Hi [~Yohan123],
Those queries are useful when you want to query data directly from Kafka. Let's
say Kafka have retention of 1 week but you're interested in data for the last 4
hours to create a live report. The current spark implementation will do
"full-table" scan of the whole week and filter the last 4 hours in spark, which
is very inefficient. My proposal is to push the timestamp filter down to Kafka
during initial query and get back only 4 hours of data, to make queries fast.
> 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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