[
https://issues.apache.org/jira/browse/KAFKA-5243?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16094629#comment-16094629
]
Joe Wood commented on KAFKA-5243:
---------------------------------
I'll raise a KIP for this as it's become essential for distributed queries to
be scalable for us. A guess at the key range may end up resulting in millions
of values, which causes unpredictable behavior.
I agree, there needs to be a special contract for ordered keys - although I
think the built in ones already comply to this.
> Request to add row limit in ReadOnlyKeyValueStore range function
> ----------------------------------------------------------------
>
> Key: KAFKA-5243
> URL: https://issues.apache.org/jira/browse/KAFKA-5243
> Project: Kafka
> Issue Type: Improvement
> Components: streams
> Affects Versions: 0.10.1.1
> Reporter: Joe Wood
>
> When using distributed queries across a cluster of stream stores it's quite
> common to use query pagination to limit the number of rows returned. The
> {{range}} function on {{ReadOnlyKeyValueStore}} only accepts the {{to}} and
> {{from}} keys. This means that the query created either unncessarily
> retrieves the entire range and manually limits the rows, or estimates the
> range based on the key values. Neither options are ideal for processing
> distributed queries.
> This suggestion is to add an overload to the {{range}} function by adding a
> third (or replacement second) argument as a suggested row limit count. This
> means that the range of keys returned will not exceed the supplied count.
> {code:java}
> // Get an iterator over a given range of keys, limiting to limit elements.
> KeyValueIterator<K,V> range(K from, K to, int limit)
> {code}
--
This message was sent by Atlassian JIRA
(v6.4.14#64029)
