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https://issues.apache.org/jira/browse/IGNITE-23193?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Pavel Tupitsyn updated IGNITE-23193:
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Description:
Some current and future features require us to "hold" the Low Watermark (LWM).
For example, while a read-only tx is active at a given timestamp, LWM can't be
moved past that timestamp.
Currently, *TxManagerImpl* subscribes to *LOW_WATERMARK_BEFORE_CHANGE* and the
event handler returns a future that waits for all relevent RO TXns to finish.
This approach is not easy to understand and reuse.
A more clear and explicit approach is to introduce the following methods to
*LowWatermark* interface:
- *void lock(lockerId, HybridTimestamp ts)*
- *void release(lockerId)*
LWM can't be adjusted past any currently locked timestamps.
> Introduce Low Watermark lock API
> --------------------------------
>
> Key: IGNITE-23193
> URL: https://issues.apache.org/jira/browse/IGNITE-23193
> Project: Ignite
> Issue Type: Improvement
> Reporter: Pavel Tupitsyn
> Assignee: Pavel Tupitsyn
> Priority: Major
> Labels: ignite-3
> Fix For: 3.1
>
>
> Some current and future features require us to "hold" the Low Watermark
> (LWM). For example, while a read-only tx is active at a given timestamp, LWM
> can't be moved past that timestamp.
> Currently, *TxManagerImpl* subscribes to *LOW_WATERMARK_BEFORE_CHANGE* and
> the event handler returns a future that waits for all relevent RO TXns to
> finish. This approach is not easy to understand and reuse.
> A more clear and explicit approach is to introduce the following methods to
> *LowWatermark* interface:
> - *void lock(lockerId, HybridTimestamp ts)*
> - *void release(lockerId)*
> LWM can't be adjusted past any currently locked timestamps.
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