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https://issues.apache.org/jira/browse/KUDU-1945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15930267#comment-15930267
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Todd Lipcon commented on KUDU-1945:
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Tables with no PK would also have the advantage that they could be sorted
within the tablet in arbitrary order, for example automatically sorted in the
way that maximizes compression ratio (eg as in Google's Capacitor format)
> Support generation of surrogate primary keys (or tables with no PK)
> -------------------------------------------------------------------
>
> Key: KUDU-1945
> URL: https://issues.apache.org/jira/browse/KUDU-1945
> Project: Kudu
> Issue Type: New Feature
> Components: client, master, tablet
> Reporter: Todd Lipcon
>
> Many use cases have data where there is no "natural" primary key. For
> example, a web log use case mostly cares about partitioning and not about
> precise sorting by timestamp, and timestamps themselves are not necessarily
> unique. Rather than forcing users to come up with their own surrogate primary
> keys, Kudu should support some kind of "auto_increment" equivalent which
> generates primary keys on insertion. Alternatively, Kudu could support tables
> which are partitioned but not internally sorted.
> The advantages would be:
> - Kudu can pick primary keys on insertion to guarantee that there is no
> compaction required on the table (eg always assign a new key higher than any
> existing key in the local tablet). This can improve write throughput
> substantially, especially compared to naive PK generation schemes that a user
> might pick such as UUID, which would generate a uniform random-insert
> workload (worst case for performance)
> - Make Kudu easier to use for such use cases (no extra client code necessary)
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