[
https://issues.apache.org/jira/browse/LUCENE-2455?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12868166#action_12868166
]
Shai Erera commented on LUCENE-2455:
------------------------------------
bq. look at how multi-pass index splitter (contrib/misc) works.
I see ...
I think this can be achieved by also deleting docs that fall outside the split
range and calling optimize() / expungeDeletes()? So, you copy the index once
(using one of the copying addIndexes methods), delete the docs that you don't
care about and optimize/expunge. Then copy the index again and repeat the
process, w/ a different range of ids. In fact, that's more or less what the
method does - only it calls addIndexes, to copy into an existing/empty
Directory.
So I think it can be changed to not call addIndexes? Only problem is that now
the method adds the docs into the target Directory directly, while in the other
solution it will need to create a Directory on the side w/ the range of
requested IDs and then copy that one into the target Dir?
But I'm not sure that's worth it to have addIndexes(IndexReader...) and the
relevant code in SM which handles the non-SegmentReader readers? Of course,
this is just one scenario, but if that's our justifying case, then I'm not sure
about how justifying it is.
> 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 :).
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
---------------------------------------------------------------------
To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org
For additional commands, e-mail: dev-h...@lucene.apache.org
