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https://issues.apache.org/jira/browse/HBASE-19357?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16279705#comment-16279705
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Anoop Sam John commented on HBASE-19357:
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I pushed this and reverted.. Now I have a worry. Sorry for not thinking that
upfront.
Making BC no longer L2 (as subject says) is just fine. We need those changes.
And also remove the combined mode = false. It will be always combined.
But I fear we can not remove the cacheDataInL1 setting.. This is because we
have file mode BC also.. When that is in place along with on heap LRU cache,
we at least have to cache the META table data within the LRU. Putting that in
file mode BC will have huge perf impact. Same with NS table. And who knows
users may have some very imp tables too.
So I tend to fix this issue by keeping the other 2 parts apart from the removal
of setter in CD for caching data in L1. Any concerns? Again sorry for
creating confusion.
> Bucket cache no longer L2 for LRU cache
> ---------------------------------------
>
> Key: HBASE-19357
> URL: https://issues.apache.org/jira/browse/HBASE-19357
> Project: HBase
> Issue Type: Sub-task
> Reporter: Anoop Sam John
> Assignee: Anoop Sam John
> Fix For: 2.0.0-beta-1
>
> Attachments: HBASE-19357.patch, HBASE-19357.patch,
> HBASE-19357_V2.patch, HBASE-19357_V3.patch, HBASE-19357_V3.patch
>
>
> When Bucket cache is used, by default we dont configure it as an L2 cache
> alone. The default setting is combined mode ON where the data blocks to
> Bucket cache and index/bloom blocks go to LRU cache. But there is a way to
> turn this off and make LRU as L1 and Bucket cache as a victim handler for L1.
> It will be just L2.
> After the off heap read path optimization Bucket cache is no longer slower
> compared to L1. We have test results on data sizes from 12 GB. The Alibaba
> use case was also with 12 GB and they have observed a ~30% QPS improve over
> the LRU cache.
> This issue is to remove the option for combined mode = false. So when Bucket
> cache is in use, data blocks will go to it only and LRU will get only index
> /meta/bloom blocks. Bucket cache will no longer be configured as a victim
> handler for LRU.
> Note : WHen external cache is in use, there only the L1 L2 thing comes. LRU
> will be L1 and external cache act as its L2. That make full sense.
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