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From "jiraposter@reviews.apache.org (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HBASE-4241) Optimize flushing of the Store cache for max versions and (new) min versions
Date Thu, 25 Aug 2011 05:12:31 GMT

    [ https://issues.apache.org/jira/browse/HBASE-4241?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13090779#comment-13090779
] 

jiraposter@reviews.apache.org commented on HBASE-4241:
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This is an automatically generated e-mail. To reply, visit:
https://reviews.apache.org/r/1650/#review1629
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http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/util/CollectionBackedScanner.java
<https://reviews.apache.org/r/1650/#comment3662>

    I think vararg form (KeyValue... incData) is more flexible than array form ([]).
    vararg has to be the last parameter.


- Ted


On 2011-08-25 04:49:36, Lars Hofhansl wrote:
bq.  
bq.  -----------------------------------------------------------
bq.  This is an automatically generated e-mail. To reply, visit:
bq.  https://reviews.apache.org/r/1650/
bq.  -----------------------------------------------------------
bq.  
bq.  (Updated 2011-08-25 04:49:36)
bq.  
bq.  
bq.  Review request for hbase, Ted Yu, Michael Stack, and Jonathan Gray.
bq.  
bq.  
bq.  Summary
bq.  -------
bq.  
bq.  This avoids flushing row versions to disk that are known to be GC'd by the next compaction
anyway.
bq.  This covers two scenarios:
bq.  1. maxVersions=N and we find at least N versions in the memstore. We can safely avoid
flushing any further versions to disk.
bq.  2. similarly minVersions=N and we find at least N versions in the memstore. Now we can
safely avoid flushing any further *expired* versions to disk.
bq.  
bq.  This changes the Store flush to use the same mechanism that used for compactions.
bq.  I borrowed some code from the tests and refactored the test code to use a new utility
class that wraps a sorted collection and then behaves like KeyValueScanner. The same class
is used to create scanner over the memstore's snapshot.
bq.  
bq.  
bq.  This addresses bug HBASE-4241.
bq.      https://issues.apache.org/jira/browse/HBASE-4241
bq.  
bq.  
bq.  Diffs
bq.  -----
bq.  
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/regionserver/Store.java
1161347 
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/main/java/org/apache/hadoop/hbase/util/CollectionBackedScanner.java
PRE-CREATION 
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/KeyValueScanFixture.java
1161347 
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestKeyValueHeap.java
1161347 
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestKeyValueScanFixture.java
1161347 
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestMinVersions.java
1161347 
bq.    http://svn.apache.org/repos/asf/hbase/trunk/src/test/java/org/apache/hadoop/hbase/regionserver/TestStore.java
1161347 
bq.  
bq.  Diff: https://reviews.apache.org/r/1650/diff
bq.  
bq.  
bq.  Testing
bq.  -------
bq.  
bq.  Ran all tests. TestHTablePool and TestDistributedLogSplitting error out (with or without
my change).
bq.  I had to change three tests that incorrectly relied on old rows hanging around after
a flush (or were otherwise incorrect).
bq.  
bq.  No new test, as this should cause no functional change.
bq.  
bq.  
bq.  Thanks,
bq.  
bq.  Lars
bq.  
bq.



> Optimize flushing of the Store cache for max versions and (new) min versions
> ----------------------------------------------------------------------------
>
>                 Key: HBASE-4241
>                 URL: https://issues.apache.org/jira/browse/HBASE-4241
>             Project: HBase
>          Issue Type: Improvement
>          Components: regionserver
>    Affects Versions: 0.92.0
>            Reporter: Lars Hofhansl
>            Assignee: Lars Hofhansl
>         Attachments: 4241-v2.txt, 4241.txt
>
>
> As discussed with with Jon, there is room for improvement in how the memstore is flushed
to disk.
> Currently only expired KVs are pruned before flushing, but we can also prune versions
if we find at least maxVersions versions in the memstore.
> The same holds for the new minversion feature: If we find at least minVersion versions
in the store we can remove all further versions that are expired.
> Generally we should use the same mechanism here that is used for Compaction. I.e. StoreScanner.
We only need to add a scanner to Memstore that can scan along the current snapshot.

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