[jira] [Commented] (IGNITE-12688) Improve performance of index inline JAVA_OBJECT fields

["Ignite TC Bot (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/IGNITE-12688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17087940#comment-17087940 ] 

Ignite TC Bot commented on IGNITE-12688:
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{panel:title=Branch: [pull/7685/head] Base: [master] : No blockers found!|borderStyle=dashed|borderColor=#ccc|titleBGColor=#D6F7C1}{panel}
[TeamCity *--> Run :: All* Results|https://ci.ignite.apache.org/viewLog.html?buildId=5240447&buildTypeId=IgniteTests24Java8_RunAll]

> Improve performance of index inline JAVA_OBJECT fields
> ------------------------------------------------------
>
>                 Key: IGNITE-12688
>                 URL: https://issues.apache.org/jira/browse/IGNITE-12688
>             Project: Ignite
>          Issue Type: Bug
>            Reporter: Konstantin Orlov
>            Assignee: Konstantin Orlov
>            Priority: Major
>          Time Spent: 10m
>  Remaining Estimate: 0h
>
> Inline JAVA_OBJECT may be reason of performance drop on index creation.
> The *root cause* is the low selectivity of current part of JAVA_OBJECT that is inlined.
> Now first N bytes of binary view of object is placed into inline space of the index.
> But the first offset where the two objects with the same type may be different is 8 (HASH_CODE_POS).
> With default inline = 10 we NEVER inline it:
> Inline format:
> 1 byte - type,
> 2 bytes - size
> >> 7 bytes - data;
> *My proposal:*
> - For metapage v4 (BPlusMetaIO) add flag *inlineObjectHash*;
> - use this flag to work in compatibility mode.
> - inline ONLY hash for JAVA_OBJECT fields for new indexes;
> Also this approach solves the inconsistent between comparison JAVA_OBJECT by inline and full value, because value comparator uses hash to compare object before compare byte arrays.



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