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https://issues.apache.org/jira/browse/HBASE-15162?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15116663#comment-15116663
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Yu Li commented on HBASE-15162:
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bq. What does the 'express' mean in the above?
'express' means 'requests set to use the block cache', and the copy-paste
description 'with the cache turned on' is to clarify this but seems failed...
For details, BLOCK_CACHE_HIT_PERCENT refers to
MetricsRegionServerWrapperImpl#getBlockCacheHitPercent and
BLOCK_CACHE_EXPRESS_HIT_PERCENT refers to
MetricsRegionServerWrapperImpl#getBlockCacheHitCachingPercent.
Regarding CombinedBlockCache, I agree that the separation seems less useful
> Add separate metrics for meta/data block hit ratio in cache
> -----------------------------------------------------------
>
> Key: HBASE-15162
> URL: https://issues.apache.org/jira/browse/HBASE-15162
> Project: HBase
> Issue Type: Sub-task
> Reporter: Yu Li
> Assignee: Yu Li
> Attachments: HBASE-15162.patch, HBASE-15162_v2.patch
>
>
> Currently we already have a metrics in name of
> {{blockCacheExpressHitPercent}} to indicate the cache hit ratio. However,
> since meta block is small and often cached in memory with a high hit ratio,
> this "mixed" metrics could not show the real data block hit ratio which is
> more concerned.
> We propose to add two new metrics to show meta and data block cache hit ratio
> separately, while reserving the old metrics for backward compatibility.
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