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https://issues.apache.org/jira/browse/IGNITE-7998?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vladimir Ozerov updated IGNITE-7998:
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    Component/s:     (was: sql)

> SQL: Improve MVCC vacuum performance by iterating over data pages instead of 
> cache tree. 
> -----------------------------------------------------------------------------------------
>
>                 Key: IGNITE-7998
>                 URL: https://issues.apache.org/jira/browse/IGNITE-7998
>             Project: Ignite
>          Issue Type: Improvement
>          Components: mvcc
>            Reporter: Roman Kondakov
>            Priority: Major
>
> At the moment vacuum process uses cache trees to find outdated (dead) entries 
> and cache and index trees to cleanup them. It is not efficient due to several 
> reasons. For example, we should lock a datapage for each cache tree entry to 
> find out if entry is dead.
> We can consider a direct iteration over datapages as a possible improvement 
> of  the vacuum process. Data page iteration prototype demonstrated 5-10 times 
> time improvement over the tree iteration.
> At first stage we need to implement direct datapages iteration only for 
> collecting dead entries links.
> At the second stage we need to consider removing links to dead entries from 
> index pages directly. In other words, we need to efficiently remove batches 
> of dead links from indexes without traversing cache and index tree one dead 
> link by one.



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