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From "Vladimir Ozerov (JIRA)" <j...@apache.org>
Subject [jira] [Assigned] (IGNITE-8386) SQL: Make sure PK index do not use wrapped object
Date Wed, 29 Aug 2018 08:02:00 GMT

     [ https://issues.apache.org/jira/browse/IGNITE-8386?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Vladimir Ozerov reassigned IGNITE-8386:
---------------------------------------

    Assignee:     (was: Vladimir Ozerov)

> SQL: Make sure PK index do not use wrapped object
> -------------------------------------------------
>
>                 Key: IGNITE-8386
>                 URL: https://issues.apache.org/jira/browse/IGNITE-8386
>             Project: Ignite
>          Issue Type: Task
>          Components: sql
>    Affects Versions: 2.4
>            Reporter: Vladimir Ozerov
>            Priority: Major
>              Labels: iep-19, performance
>
> Currently PK may be built over the whole {{_KEY}} column, i.e. the whole binary object.
This could happen in two cases:
> 1) Composite PK
> 2) Plain PK but with {{WRAP_KEY}} option.
> This is critical performance issue for two reasons:
> 1) This index is effectively useless and cannot be used in any sensible queries; it just
wastes space and makes updates slower
> 2) Binary object typically has common header bytes what may lead to excessive number
of comparisons during index update.
> To mitigate the problem we need to ensure that index is *never* built over {{_KEY}},
Instead, we must always extract target columns and build normal index over them.



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