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https://issues.apache.org/jira/browse/HBASE-8151?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Ted Yu updated HBASE-8151:
--------------------------
Attachment: 8151-0.96-v3.txt
Patch v3 fixes the following compilation error:
{code}
[ERROR] Failed to execute goal
org.apache.maven.plugins:maven-compiler-plugin:2.5.1:compile (default-compile)
on project hbase-server: Compilation failure
[ERROR]
/Users/tyu/trunk/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/StoreFile.java:[659,13]
cannot find symbol
[ERROR] symbol : constructor
Writer(org.apache.hadoop.fs.FileSystem,org.apache.hadoop.fs.Path,int,org.apache.hadoop.hbase.io.compress.Compression.Algorithm,org.apache.hadoop.hbase.io.hfile.HFileDataBlockEncoder,org.apache.hadoop.conf.Configuration,org.apache.hadoop.hbase.io.hfile.CacheConfig,org.apache.hadoop.hbase.KeyValue.KVComparator,org.apache.hadoop.hbase.regionserver.BloomType,long,org.apache.hadoop.hbase.util.ChecksumType,int)
[ERROR] location: class org.apache.hadoop.hbase.regionserver.StoreFile.Writer
{code}
> Small optimization in HFileReaderV2
> -----------------------------------
>
> Key: HBASE-8151
> URL: https://issues.apache.org/jira/browse/HBASE-8151
> Project: HBase
> Issue Type: Bug
> Reporter: Lars Hofhansl
> Attachments: 8151-0.94.txt, 8151-0.96.txt, 8151-0.96-v2.txt,
> 8151-0.96-v3.txt
>
>
> HFiles V2 store the memstoreTS of each KV.
> In many cases all the KVs in an HFile will have a memstoreTS of 0 (that is
> the case when at the time the HFile was written there are no KVs that were
> created after the oldest still active scanner - which is frequently the case).
> In that case we:
> # do not need to decode the memstoreTS (a vlong), since we know its value is
> 0 and its length is 1 byte.
> # when we compact HFiles and all of the involved files have only KVs with
> memstoreTS = 0 we know ahead of time that all KVs meet this condition and we
> do not need to store the memstoreTS in the new HFile.
> This issue will cover the first part. The performance improvement will be
> modest as it is fairly cheap to decode vlongs of size 1.
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