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https://issues.apache.org/jira/browse/CASSANDRA-2988?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13143562#comment-13143562
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Melvin Wang commented on CASSANDRA-2988:
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ah, I was wrong about that comment. Looks like they are pretty much alike
except one place, where in RandomAccessFile.reBuffer(), it uses super.read to
read whereas the patch uses FileChannel to read. If
java.io.RandomAccessFile.read performs same as FileChannel.read, I will discard
this patch.
> Improve SSTableReader.load() when loading index files
> -----------------------------------------------------
>
> Key: CASSANDRA-2988
> URL: https://issues.apache.org/jira/browse/CASSANDRA-2988
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Melvin Wang
> Assignee: Melvin Wang
> Priority: Minor
> Fix For: 1.0.2
>
> Attachments: 2988-2-cleaned.txt, 2988-parallel-v2.txt, c2988-2-v2,
> c2988-modified-buffer.patch, c2988-parallel-load-sstables.patch
>
>
> * when we create BufferredRandomAccessFile, we pass skipCache=true. This
> hurts the read performance because we always process the index files
> sequentially. Simple fix would be set it to false.
> * multiple index files of a single column family can be loaded in parallel.
> This buys a lot when you have multiple super large index files.
> * we may also change how we buffer. By using BufferredRandomAccessFile, for
> every read, we need bunch of checking like
> - do we need to rebuffer?
> - isEOF()?
> - assertions
> These can be simplified to some extent. We can blindly buffer the index
> file by chunks and process the buffer until a key lies across boundary of a
> chunk. Then we rebuffer and start from the beginning of the partially read
> key. Conceptually, this is same as what BRAF does but w/o the overhead in the
> read**() methods in BRAF.
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