Alexey Scherbakov created IGNITE-13395:
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Summary: 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
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.
The second is used only for SQL queries to ensure consistent result on topology
change 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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