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From "Mingjie Lai" <mjla...@gmail.com>
Subject Re: Review Request: HBASE-2468: Improvements to prewarm META cache on clients.
Date Sun, 13 Jun 2010 07:49:51 GMT

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(Updated 2010-06-13 00:49:50.977413)

Review request for hbase, Todd Lipcon and stack.


1) resolved conflicts from the latest code commits
2) added get/setRegionCachePrefetch() in HTable, removed isRegionCachePrefetchEnabled(), enableRegionCachePrefetch(),
3) in MetaScanner, added Math.min(rowLimit, configuration.getInt(...))


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

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
- 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.

Diffs (updated)

  src/main/java/org/apache/hadoop/hbase/client/HConnection.java 853164d 
  src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java 03cbf8d 
  src/main/java/org/apache/hadoop/hbase/client/HTable.java 8e47f2d 
  src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java f11ada7 
  src/test/java/org/apache/hadoop/hbase/client/TestFromClientSide.java 95e494a 

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


Unit tests passed locally for me. 



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