[jira] Issue Comment Edited: (LUCENE-2455) Some house cleaning in addIndexes*

["Andrzej Bialecki (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/LUCENE-2455?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12868177#action_12868177 ] 

Andrzej Bialecki  edited comment on LUCENE-2455 at 5/17/10 7:36 AM:
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FYI, I'm working on a different version of IndexSplitter that uses the logic in SegmentMerger directly, without going through IW.addIndexes(FilterIndexReader).

However, there are other applications for which this API is crucial, e.g. LUCENE-1812 or IndexSorter (in Nutch) - in short, any client apps that want to merge-in index data that does not correspond 1:1 to a Directory. For this reason I think the pair of IndexWriter.addIndexes(IndexReader...) and FilterIndexReader abstraction is extremely useful and that IndexWriter.addIndexes(Directory...) is not a sufficient replacement.

(edit: unless there is a better user-level API based on the flex producers/consumers...)

      was (Author: ab):
    FYI, I'm working on a different version of IndexSplitter that uses the logic in SegmentMerger directly, without going through IW.addIndexes(FilterIndexReader).

However, there are other applications for which this API is crucial, e.g. LUCENE-1812 or IndexSorter (in Nutch) - in short, any client apps that want to merge-in index data that does not correspond 1:1 to a Directory. For this reason I think the pair of IndexWriter.addIndexes(IndexReader...) and FilterIndexReader abstraction is extremely useful and that IndexWriter.addIndexes(Directory...) is not a sufficient replacement.
  
> Some house cleaning in addIndexes*
> ----------------------------------
>
>                 Key: LUCENE-2455
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2455
>             Project: Lucene - Java
>          Issue Type: Improvement
>          Components: Index
>            Reporter: Shai Erera
>            Assignee: Shai Erera
>            Priority: Trivial
>             Fix For: 3.1, 4.0
>
>         Attachments: LUCENE-2455_3x.patch
>
>
> Today, the use of addIndexes and addIndexesNoOptimize is confusing - 
> especially on when to invoke each. Also, addIndexes calls optimize() in 
> the beginning, but only on the target index. It also includes the 
> following jdoc statement, which from how I understand the code, is 
> wrong: _After this completes, the index is optimized._ -- optimize() is 
> called in the beginning and not in the end. 
> On the other hand, addIndexesNoOptimize does not call optimize(), and 
> relies on the MergeScheduler and MergePolicy to handle the merges. 
> After a short discussion about that on the list (Thanks Mike for the 
> clarifications!) I understand that there are really two core differences 
> between the two: 
> * addIndexes supports IndexReader extensions
> * addIndexesNoOptimize performs better
> This issue proposes the following:
> # Clear up the documentation of each, spelling out the pros/cons of 
>   calling them clearly in the javadocs.
> # Rename addIndexesNoOptimize to addIndexes
> # Remove optimize() call from addIndexes(IndexReader...)
> # Document that clearly in both, w/ a recommendation to call optimize() 
>   before on any of the Directories/Indexes if it's a concern. 
> That way, we maintain all the flexibility in the API - 
> addIndexes(IndexReader...) allows for using IR extensions, 
> addIndexes(Directory...) is considered more efficient, by allowing the 
> merges to happen concurrently (depending on MS) and also factors in the 
> MP. So unless you have an IR extension, addDirectories is really the one 
> you should be using. And you have the freedom to call optimize() before 
> each if you care about it, or don't if you don't care. Either way, 
> incurring the cost of optimize() is entirely in the user's hands. 
> BTW, addIndexes(IndexReader...) does not use neither the MergeScheduler 
> nor MergePolicy, but rather call SegmentMerger directly. This might be 
> another place for improvement. I'll look into it, and if it's not too 
> complicated, I may cover it by this issue as well. If you have any hints 
> that can give me a good head start on that, please don't be shy :). 

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