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https://issues.apache.org/jira/browse/IGNITE-13395?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Alexey Scherbakov updated IGNITE-13395:
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Ignite Flags: (was: Docs Required,Release Notes Required)
> Get rid of partition group reservations.
> ----------------------------------------
>
> Key: IGNITE-13395
> URL: https://issues.apache.org/jira/browse/IGNITE-13395
> Project: Ignite
> Issue Type: Improvement
> Affects Versions: 2.9
> Reporter: Alexey Scherbakov
> Priority: Major
> Fix For: 2.10
>
>
> Currently we have two ways to prevent a partition from being evicted if it's
> no longer owner by affinity:
> 1. "normal" reservation using GridDhtLocalPartition#reserve/release
> 2. "group" reservation using GridDhtPartitionsReservation, used as an
> optimization for reserving batches of partitions at once.
> The second is used only for SQL queries to ensure consistent result on
> unstable topology and adds a lot of complexity to SQL engine and partition
> eviction code. In fact, the same can be achieved using only first type of
> reservation.
> I propose to get rid of group reservations using the following algorythm:
> 1. On PME all owning partitions are normally reserved.
> 2. A query counter for topology version is introduced.
> 3. If a query counter reaches zero for current topVer and where is a new
> topVer incompatible with current, previously reserved partitions are released.
> Using such approach it's possible to totally remove any reservation
> management from SQL engine (except maintaining a counter), make it more
> simple and efficient.
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