chenxu14 commented on issue #909: HBASE-23355 Bypass the prefetch operation if 
HFiles are generated through flush or compaction
URL: https://github.com/apache/hbase/pull/909#issuecomment-565678380
 
 
   > Where is the new addition being exploited though? 
   
   We declared a prefetchOnOpen variable in ReaderContext,  it’s default value 
is false (means Prefetch is not performed by default), But when region 
opens(code in HStore#openStoreFiles) or bulkload happend, we will modify the 
prefetchOnOpen value according to CacheConf#shouldPrefetchOnOpen()
   
   > what about the original supposition by Anoop -- double cache. Are we NOT 
double caching after this fix?
   
   The double cache what I understand is that we may cache the same block twice 
through cacheOnWrite and prefetchOnFlush(Pardon the name) or 
prefetchOnCompaction,
   So here we ignore the flush and compaction case when do prefect.

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