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https://issues.apache.org/jira/browse/CASSANDRA-21632?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Brandon Williams updated CASSANDRA-21632:
-----------------------------------------
     Bug Category: Parent values: Degradation(12984)Level 1 values: Performance 
Bug/Regression(12997)
       Complexity: Normal
    Discovered By: User Report
    Fix Version/s: 5.0.x
                   6.x
                   7.x
         Severity: Normal
           Status: Open  (was: Triage Needed)

> BTI partition index preload is unbounded
> ----------------------------------------
>
>                 Key: CASSANDRA-21632
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-21632
>             Project: Apache Cassandra
>          Issue Type: Bug
>          Components: Local/SSTable, Local/Startup and Shutdown
>            Reporter: Alexandre Viau
>            Priority: Normal
>              Labels: patch-available
>             Fix For: 5.0.x, 6.x, 7.x
>
>          Time Spent: 20m
>  Remaining Estimate: 0h
>
> When a table has bloom_filter_fp_chance = 1, PartitionIndex.load warms the 
> entire Partitions.db by seeking to every 4096-byte offset and reading a 
> single byte. The warm is unbounded. Nothing relates the amount read to the 
> amount of page cache the node can actually retain
>  
> On our cluster (5.4 TiB and 32.5B partitions per node, bloom_filter_fp_chance 
> = 1, Partitions.db totalling 309.47 GiB across 798 files, or 81,125,849 pages 
> to touch), roughly 70 GiB of page cache is available to the process. The warm 
> reads 309 GiB to retain at most a fraction of it, and startup takes roughly 
> 90 minutes, essentially all of it in SSTableReader.openAll.



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