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https://issues.apache.org/jira/browse/IGNITE-19819?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vyacheslav Koptilin reassigned IGNITE-19819:
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Assignee: (was: Vyacheslav Koptilin)
> Lease batches compaction
> ------------------------
>
> Key: IGNITE-19819
> URL: https://issues.apache.org/jira/browse/IGNITE-19819
> Project: Ignite
> Issue Type: Improvement
> Reporter: Denis Chudov
> Priority: Major
> Labels: ignite-3
>
> *Motivation*
> After IGNITE-19578 leases should be stored as a single batch in meta storage.
> However, the size of such a batch is significant and can be reduced.
> Each lease contains group name, leaseholder name, left and right timestamp
> and couple of boolean flags.
> Many leases share the same leaseholder. Also, many leases share the same
> right border, as batch of leases are renewed on every iteration of lease
> updater and get the same right border.
> So, the compacted data structure for all leases could be a map
> {code:java}
> right border -> set of leaseholders -> set of leases which contain only group
> name, left border and flags.{code}
> It is important that this data structure is applicable to meta storage
> representation, in-memory representation of leases should remain the same.
> *Definition of done*
> Amount of space required for storing leases is significantly reduced.
> *Implementation notes*
> The key should be prefix + right border. On each iteration the corresponding
> right border should be removed and new one put, so on each iteration there
> will be done just one meta storage invoke.
> To avoid ABA problem during leases' updates via invokes, entries should be
> versioned, this can be done by assigning unique version to each right border
> key. There are cases when all leaseholders can be removed from some entry and
> then another leaseholders added again (e.g. accepting leases and removing
> them from right border that matches long-term unaccepted leases, and later
> adding the regular leases to the same right border). In this cases the entry
> should not be removed from meta storage, in spite it doesn't have leases, to
> preserve the version of the entry.
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