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From "Yury Gerzhedovich (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (IGNITE-8386) SQL: Make sure PK index do not use wrapped object
Date Mon, 12 Nov 2018 08:29:00 GMT

    [ https://issues.apache.org/jira/browse/IGNITE-8386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16683399#comment-16683399

Yury Gerzhedovich commented on IGNITE-8386:


1) Provided.
2) As I understand we don't have such issue for secondary indexes. Correct me if I wrong.

> 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
>            Assignee: Yury Gerzhedovich
>            Priority: Major
>              Labels: iep-19, performance
>             Fix For: 2.8
> 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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