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https://issues.apache.org/jira/browse/CASSANDRA-10010?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14660758#comment-14660758
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Tyler Hobbs commented on CASSANDRA-10010:
-----------------------------------------
I've created a dtest that reproduces the issue through a deletion here:
https://github.com/thobbs/cassandra-dtest/tree/CASSANDRA-10010-repro. This
seems to only be a problem for 2.1 and 2.2, but not 3.0.
> Paging on DISTINCT queries repeats result when first row in partition changes
> -----------------------------------------------------------------------------
>
> Key: CASSANDRA-10010
> URL: https://issues.apache.org/jira/browse/CASSANDRA-10010
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Reporter: Tyler Hobbs
> Assignee: Benjamin Lerer
> Priority: Minor
> Fix For: 2.1.x, 2.2.x
>
>
> When paging, we always check new pages to see if they start with the same row
> that the previous page ended with, and if so, we trim that row to avoid
> duplicates. With {{DISTINCT}} queries, we only fetch the first row in each
> partition. If that row happens to change (it's deleted, or another row is
> inserted at the front of the partition) in between fetching the two pages,
> our check for a matching row will fail, resulting in a duplicate row being
> returned.
> It seems like the correct fix is to handle {{DISTINCT}} queries specially and
> only check to see if the partition key matches the last returned one instead
> checking that the rows match.
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