[jira] [Commented] (KUDU-1945) Support generation of surrogate primary keys (or tables with no PK)

["Todd Lipcon (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/KUDU-1945?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15930267#comment-15930267 ] 

Todd Lipcon commented on KUDU-1945:
-----------------------------------

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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