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https://issues.apache.org/jira/browse/HBASE-23066?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16988077#comment-16988077
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Jacob LeBlanc commented on HBASE-23066:
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{quote}The latest patch what Ram published yesterday is having this aspect
also. We were discussing it offline. The allow cache on write for compacted
files should be a global config as well as one can override it at Table or CF
levels. On HTD or HCD level, user can do setConfigure with same config name and
override the global value.
{quote}
OK, that sounds great! I did check on that PR and saw only the global setting,
which is why I suggested that for my organization's use case at least we would
need a table or CF specific setting. Let me know if there's anything else
needed on my end.
> 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, 1.6.0
>
> 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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