Andrew Kyle Purtell updated HBASE-23066:
    Fix Version/s:     (was: 1.6.0)

> Allow cache on write during compactions when prefetching is enabled
> -------------------------------------------------------------------
>                 Key: HBASE-23066
>                 URL: https://issues.apache.org/jira/browse/HBASE-23066
>             Project: HBase
>          Issue Type: Improvement
>          Components: Compaction, regionserver
>    Affects Versions: 1.4.10
>            Reporter: Jacob LeBlanc
>            Assignee: Jacob LeBlanc
>            Priority: Minor
>             Fix For: 2.3.0, 1.5.1
>         Attachments: HBASE-23066.patch, performance_results.png, 
> prefetchCompactedBlocksOnWrite.patch
> In cases where users care a lot about read performance for tables that are 
> small enough to fit into a cache (or the cache is large enough), 
> prefetchOnOpen can be enabled to make the entire table available in cache 
> after the initial region opening is completed. Any new data can also be 
> guaranteed to be in cache with the cacheBlocksOnWrite setting.
> However, the missing piece is when all blocks are evicted after a compaction. 
> We found very poor performance after compactions for tables under heavy read 
> load and a slower backing filesystem (S3). After a compaction the prefetching 
> threads need to compete with threads servicing read requests and get 
> constantly blocked as a result. 
> This is a proposal to introduce a new cache configuration option that would 
> cache blocks on write during compaction for any column family that has 
> prefetch enabled. This would virtually guarantee all blocks are kept in cache 
> after the initial prefetch on open is completed allowing for guaranteed 
> steady read performance despite a slow backing file system.

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