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Posted to issues@ignite.apache.org by "Andrey Mashenkov (Jira)" <ji...@apache.org> on 2021/05/20 08:36:00 UTC
[jira] [Updated] (IGNITE-14557) Improve row layout. Skip writing
null-map and vartable when possible.
[ https://issues.apache.org/jira/browse/IGNITE-14557?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Andrey Mashenkov updated IGNITE-14557:
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Summary: Improve row layout. Skip writing null-map and vartable when possible. (was: Improve row layout. Skip null-map and vartable when possible.)
> Improve row layout. Skip writing null-map and vartable when possible.
> ---------------------------------------------------------------------
>
> Key: IGNITE-14557
> URL: https://issues.apache.org/jira/browse/IGNITE-14557
> Project: Ignite
> Issue Type: Improvement
> Reporter: Andrey Mashenkov
> Assignee: Andrey Mashenkov
> Priority: Major
> Labels: iep-54, ignite-3
> Time Spent: 10m
> Remaining Estimate: 0h
>
> h3. Motivation.
> When one try to read a column value from a row, the very first check will be a null-check.
> As Null-Table resides right after an Offset-Table, the we need 2 jumps to for the null-check.
> h3. Description.
> Assuming, Null-Table reserves a bit for each columns even if the columns is not Nullable,
> Null-table has constant size (within same version of schema) and we no need extra bytes to persist it's length into the tuple.
> * Null-checks will not require extra read for Offset-Table size and extra jump.
> * Offset-Table will not need extra read/jump to reach as Null-Table size is constant.
> Let's just swap these tables in layout and fix docs README.md and IEP.
>
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