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https://issues.apache.org/jira/browse/HBASE-14556?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14956420#comment-14956420
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Heng Chen commented on HBASE-14556:
-----------------------------------
{quote}
For large datasets it is not viable to load all blocks into memory, but to
speed up access it still makes sense to prefetch the index blocks (being block
index and Bloom filter blocks).
{quote}
As current logic, when readblock, index blocks will be cached already. As
code below, after read block from hdfs, it will call {{shouldCacheBlockOnRead}}
to decide whether we should cache the block.
{code}
public boolean shouldCacheBlockOnRead(BlockCategory category) {
return isBlockCacheEnabled()
&& (cacheDataOnRead ||
category == BlockCategory.INDEX ||
category == BlockCategory.BLOOM ||
(prefetchOnOpen &&
(category != BlockCategory.META &&
category != BlockCategory.UNKNOWN)));
}
{code}
> Make prefetchOnOpen configurable for index and/or data blocks
> -------------------------------------------------------------
>
> Key: HBASE-14556
> URL: https://issues.apache.org/jira/browse/HBASE-14556
> Project: HBase
> Issue Type: Bug
> Components: BlockCache, regionserver
> Reporter: Lars George
>
> This came up in user discussions. It would be great to add an extra option to
> the {{CacheConfig}} that allows to specify what blocks are cached during
> region/file opening. This should allows to set {{BlockIndexOnly}},
> {{BloomFilterOnly}}, {{AllIndexesOnly}}, {{DataOnly}}, and {{AllBlocks}}.
> For large datasets it is not viable to load all blocks into memory, but to
> speed up access it still makes sense to prefetch the index blocks (being
> block index and Bloom filter blocks).
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