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https://issues.apache.org/jira/browse/HBASE-13472?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14513525#comment-14513525
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Anoop Sam John commented on HBASE-13472:
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bq. Consider table quota support with an option for region size limits as % of
total heap consumed by regions for a given table. Warn at soft limit. Refuse
writes if over hard limit.
Ya.. I was thinking about this as a work after the offheaping Jira. When we can
have HBase RS with more and more cache, we would need better tuning of the size
shares for different tables. So Quotas can help here.
We have L1 and L2 cache now (In 2 modes). I was thinking whether we can extend
this. We have L1 cache in on heap and L2 in Offheap (BC) and a L3 in BC file
mode (SSDs). Out of scope of this Jira. Just noting down here as here we speak
about keeping more data in cache. We would need quota control and table level
priority control.... cc [~stack]
> Polish IN_MEMORY table behavior
> -------------------------------
>
> Key: HBASE-13472
> URL: https://issues.apache.org/jira/browse/HBASE-13472
> Project: HBase
> Issue Type: Task
> Reporter: Andrew Purtell
>
> For a long time we've been able to support a mode of operation that keeps as
> much table data as possible in memory, so HBase can be used as an 'in-memory'
> DB with fully durable WAL and write-behind persistence of table data. However:
> - There are a set of relevant schema options (IN_MEMORY, CACHE_ON_WRITE,
> PREFETCH_BLOCKS_ON_OPEN, block encoding), so set up isn't simple. We should
> have a shortcut that sets all this up in one place. I'm thinking a utility
> class with static helpers that configure a table descriptor with all of the
> needed bits. (Other ideas?)
> - We don't have a safety valve. An in-memory table can become too large,
> where it falls out of blockcache and performs poorly without warning because
> it's become too big. Consider table quota support with an option for region
> size limits as % of total heap consumed by regions for a given table. Warn at
> soft limit. Refuse writes if over hard limit.
> Follow on work can investigate options hooking up to offheap work. That's not
> in scope here.
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