[
https://issues.apache.org/jira/browse/MAHOUT-1286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13736962#comment-13736962
]
Peng Cheng edited comment on MAHOUT-1286 at 8/12/13 4:54 PM:
-------------------------------------------------------------
The idea of ArrayMap has been discarded due to its impractical time consumption
of insertion (O( n ) for a batch insertion) and query (O(logn)). I have moved
back to HashMap. Due to the same reason, I feel that using Sparse Row/Column
matrix may have the same problem.
was (Author: peng):
The idea of ArrayMap has been discarded due to its impractical time
consumption of insertion (O(n) for a batch insertion) and query (O(logn)). I
have moved back to HashMap. Due to the same reason, I feel that using Sparse
Row/Column matrix may have the same problem.
> Memory-efficient DataModel, supporting fast online updates and element-wise
> iteration
> -------------------------------------------------------------------------------------
>
> Key: MAHOUT-1286
> URL: https://issues.apache.org/jira/browse/MAHOUT-1286
> Project: Mahout
> Issue Type: Improvement
> Components: Collaborative Filtering
> Affects Versions: 0.9
> Reporter: Peng Cheng
> Assignee: Sean Owen
> Labels: collaborative-filtering, datamodel, patch, recommender
> Fix For: 0.9
>
> Attachments: InMemoryDataModel.java, InMemoryDataModelTest.java
>
> Original Estimate: 336h
> Remaining Estimate: 336h
>
> Most DataModel implementation in current CF component use hash map to enable
> fast 2d indexing and update. This is not memory-efficient for big data set.
> e.g. Netflix prize dataset takes 11G heap space as a FileDataModel.
> Improved implementation of DataModel should use more compact data structure
> (like arrays), this can trade a little of time complexity in 2d indexing for
> vast improvement in memory efficiency. In addition, any online recommender or
> online-to-batch converted recommender will not be affected by this in
> training process.
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira
