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From "Melvin Wang (JIRA)" <j...@apache.org>
Subject [jira] [Created] (CASSANDRA-2988) Improve SSTableReader.load() when loading index files
Date Wed, 03 Aug 2011 01:34:27 GMT
Improve SSTableReader.load() when loading index files
-----------------------------------------------------

                 Key: CASSANDRA-2988
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2988
             Project: Cassandra
          Issue Type: Improvement
            Reporter: Melvin Wang


* 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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