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From "Mingjie Lai" <mjla...@gmail.com>
Subject Re: Review Request: HBASE-2468: Improvements to prewarm META cache on clients.
Date Wed, 02 Jun 2010 08:13:42 GMT

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This is an automatically generated e-mail. To reply, visit:
http://review.hbase.org/r/98/
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(Updated 2010-06-02 01:13:42.272750)


Review request for hbase.


Changes
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1. Fix some issues pointed out by Todd.
2. Re-do MetaScanner so it will start scanning Meta from the region where the given user table
row resides, instead of scanning from the next region row in Meta.


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 (updated)
-----

  src/main/java/org/apache/hadoop/hbase/client/HConnection.java 853164d 
  src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java ed18092 
  src/main/java/org/apache/hadoop/hbase/client/HTable.java 7ec95cb 
  src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java d3a0c07 
  src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java 95e494a 

Diff: http://review.hbase.org/r/98/diff


Testing
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Unit tests passed locally for me. 


Thanks,

Mingjie


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