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Posted to commits@cassandra.apache.org by "Jonathan Ellis (JIRA)" <ji...@apache.org> on 2011/09/21 01:26:08 UTC
[jira] [Updated] (CASSANDRA-2988) Improve SSTableReader.load() when
loading index files
[ https://issues.apache.org/jira/browse/CASSANDRA-2988?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Jonathan Ellis updated CASSANDRA-2988:
--------------------------------------
Attachment: 2988-parallel-v2.txt
I'll do the opposite of Pavel and start with the second. :)
v2 of parallel sstable opening attached. Better code reuse, and caps the thread pool at #cores to avoid too much contention.
> 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: 1.0.1
>
> Attachments: 2988-parallel-v2.txt, 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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