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https://issues.apache.org/jira/browse/HBASE-2468?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12873849#action_12873849
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HBase Review Board commented on HBASE-2468:
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Message from: "Mingjie Lai" <mjla...@gmail.com>
bq. On 2010-05-28 15:05:08, Ryan Rawson wrote:
bq. > src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java,
line 1604
bq. > <http://review.hbase.org/r/98/diff/3/?file=741#file741line1604>
bq. >
bq. > What does this method actually do? If its a predicate start it with
'is'. Also precaching should be off by default...
bq. > Is it?
Will add ``is'' prefix to this method.
Pre-caching (in case of a cache miss) is set to ``on'' by default right now,
according to stack:
``I'm for default behavior being grabbing more than just the one row – ten or
something. Regards full-table scan as default, I think it should be an option
(Its a nice option to have). ''
https://issues.apache.org/jira/browse/HBASE-2468?focusedCommentId=12870321&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12870321
- Mingjie
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> Improvements to prewarm META cache on clients
> ---------------------------------------------
>
> Key: HBASE-2468
> URL: https://issues.apache.org/jira/browse/HBASE-2468
> Project: HBase
> Issue Type: Improvement
> Components: client
> Reporter: Todd Lipcon
> Assignee: Mingjie Lai
> Fix For: 0.21.0
>
> Attachments: HBASE-2468-trunk.patch
>
>
> A couple different use cases cause storms of reads to META during startup.
> For example, a large MR job will cause each map task to hit meta since it
> starts with an empty cache.
> A couple possible improvements have been proposed:
> - MR jobs could ship a copy of META for the table in the DistributedCache
> - Clients could prewarm cache by doing a large scan of all the meta for the
> table instead of random reads for each miss
> - Each miss could fetch ahead some number of rows in META
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