[jira] [Commented] (CASSANDRA-4324) Implement Lucene FST in for key index

["Yuki Morishita (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-4324?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13406240#comment-13406240 ] 

Yuki Morishita commented on CASSANDRA-4324:
-------------------------------------------

Jason,

Thanks for the patch.
Current IndexSummary has list of DecoratedKeys and list of positions, but search is done against KeyBound as well. Both DecoratedKey and KeyBound are subclass of RowPosition and are compared using their Tokens. So, I think you have to construct FST against Token.
For implementation, it would be better to keep all lucene FST related classes inside IndexSummary and not expose them directory to SSTableReader etc.

Also, can you provide micro benchmark (memory, cpu time...) of IndexSummary between current implementation and FST?
                
> Implement Lucene FST in for key index
> -------------------------------------
>
>                 Key: CASSANDRA-4324
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4324
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jason Rutherglen
>            Assignee: Jason Rutherglen
>            Priority: Minor
>             Fix For: 1.2
>
>         Attachments: CASSANDRA-4324.patch
>
>
> The Lucene FST data structure offers a compact and fast system for indexing Cassandra keys.  More keys may be loaded which in turn should seeks faster.
> * Update the IndexSummary class to make use of the Lucene FST, overriding the serialization mechanism.
> * Alter SSTableReader to make use of the FST seek mechanism

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