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From "Todd Lipcon" <t...@cloudera.com>
Subject Re: Review Request: HBASE-2468: Improvements to prewarm META cache on clients.
Date Thu, 10 Jun 2010 01:08:15 GMT

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Looking good! Just a few notes.


src/main/java/org/apache/hadoop/hbase/client/HConnection.java
<http://review.hbase.org/r/98/#comment813>

    I thought we were collapsing these two calls into setRegionCachePrefetchEnabled(tableName,
enabled)?



src/main/java/org/apache/hadoop/hbase/client/HConnectionManager.java
<http://review.hbase.org/r/98/#comment816>

    I don't entirely understand why we key these hashes by integer, but it seems like you're
following the status quo, so doesn't need to be addressed in this patch.



src/main/java/org/apache/hadoop/hbase/client/HTable.java
<http://review.hbase.org/r/98/#comment822>

    I still don't quite understand the logic about why these should be static. Previously
you pointed to the enable/disable calls, but those are more like admin calls, not calls that
affect client behavior. Anyone else have an opinion?



src/main/java/org/apache/hadoop/hbase/client/MetaScanner.java
<http://review.hbase.org/r/98/#comment823>

    I think this should be Math.max(rowLimit, configuration.getInt(...)) - if we only want
to scan 5 rows, we don't want the scanner to prefetch 100 for us.


- Todd


On 2010-06-09 15:50:59, Mingjie Lai wrote:
> 
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> This is an automatically generated e-mail. To reply, visit:
> http://review.hbase.org/r/98/
> -----------------------------------------------------------
> 
> (Updated 2010-06-09 15:50:59)
> 
> 
> Review request for hbase, Todd Lipcon and stack.
> 
> 
> 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 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
> -------
> 
> Unit tests passed locally for me. 
> 
> 
> Thanks,
> 
> Mingjie
> 
>


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