Re: Review Request: HBASE-2468: Improvements to prewarm META cache on clients.

[Mingjie Lai <mj...@gmail.com>]

> On 2010-05-28 15:05:08, Ryan Rawson wrote:
> > src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java, line 1604
> > <http://review.hbase.org/r/98/diff/3/?file=741#file741line1604>
> >
> >     What does this method actually do? If its a predicate start it with 'is'.  Also precaching should be off by default...
> >      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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On 2010-05-28 13:20:33, Mingjie Lai wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> http://review.hbase.org/r/98/
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> 
> (Updated 2010-05-28 13:20:33)
> 
> 
> Review request for hbase.
> 
> 
> Summary
> -------
> 
> HBASE-2468: Improvements to prewarm META cache on clients.
> 
> Changes:
> 1. Add new HTable methods which support region info de/serialation, and region cache prewarm: 
> - void serializeRegionInfo(): clients could perform a large scan for all the meta for the table, serialize the meta to a file. MR job can ship a copy of the meta for the table in the DistributedCache
> - Map<HRegionInfo, HServerAddress> deserializeRegionInfo(): MR job can deserialize the region info from the DistributedCache 
> - prewarmRegionCache(Map<HRegionInfo, HServerAddress> regionMap): MR job can prewarm local region cache by the deserialized region info.
> 
> 2. For each client, each region cache read-miss could trigger read-ahead some number of rows in META. This option could be turned on and off for one particular table. 
> 
> 
> This addresses bug HBASE-2468.
>     http://issues.apache.org/jira/browse/HBASE-2468
> 
> 
> Diffs
> -----
> 
>   src/main/java/org/apache/hadoop/hbase/client/HConnection.java 853164d 
>   src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java 09de2ac 
>   src/main/java/org/apache/hadoop/hbase/client/HTable.java 7ec95cb 
>   src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java 3de661e 
>   src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java 95e494a 
> 
> Diff: http://review.hbase.org/r/98/diff
> 
> 
> Testing
> -------
> 
> Unit tests passed locally for me. 
> 
> 
> Thanks,
> 
> Mingjie
> 
>