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https://issues.apache.org/jira/browse/HBASE-30025?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Vladimir Rodionov updated HBASE-30025:
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Summary: Wire TieredExclusiveTopology as a CombinedBlockCache-compatible
CacheAccessService (was: Add TieredInclusiveTopology support)
> Wire TieredExclusiveTopology as a CombinedBlockCache-compatible
> CacheAccessService
> ----------------------------------------------------------------------------------
>
> Key: HBASE-30025
> URL: https://issues.apache.org/jira/browse/HBASE-30025
> Project: HBase
> Issue Type: New Feature
> Components: BlockCache, Performance
> Reporter: Vladimir Rodionov
> Assignee: Vladimir Rodionov
> Priority: Major
> Fix For: 4.0.0-alpha-1
>
>
> h2. Description
> Add support for an explicit *TieredInclusiveTopology* as an alternative cache
> topology for coordinating L1 and L2 cache tiers.
> In an inclusive topology, blocks present in the upper tier (L1) are also
> retained in the lower tier (L2). This differs from the existing exclusive
> behavior (modeled by *TieredExclusiveTopology*), where a block resides in
> only one tier at a time.
> h3. Scope
> * Introduce *TieredInclusiveTopology* implementing L1/L2 coordination with
> inclusive semantics
> * Implement lookup behavior:
> ** check L1 first, then L2 on miss
> * Implement promotion behavior:
> ** on L2 hit, copy block into L1 while retaining it in L2
> * Define eviction behavior:
> ** eviction from L1 does not affect L2
> * Integrate with existing topology abstraction (*CacheTopology*)
> h3. Notes
> * No change to default behavior — *TieredExclusiveTopology* remains the
> default configuration
> * Existing cache implementations (*LruBlockCache*, *BucketCache*) remain
> unchanged
> * This topology is introduced primarily for flexibility and experimentation
> * Enables evaluation of different trade-offs between:
> ** memory efficiency (exclusive)
> ** simplicity and stability (inclusive)
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