lucene-dev mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Jason Rutherglen (JIRA)" <j...@apache.org>
Subject [jira] Commented: (LUCENE-2680) Improve how IndexWriter flushes deletes against existing segments
Date Tue, 09 Nov 2010 04:02:06 GMT

    [ https://issues.apache.org/jira/browse/LUCENE-2680?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12929927#action_12929927
] 

Jason Rutherglen commented on LUCENE-2680:
------------------------------------------

Ok, TestThreadedOptimize works when the DW sync'ed pushSegmentInfos method
isn't called anymore (no extra per-segment deleting is going on), and stops
working when pushSegmentInfos is turned back on. Something about the sync
on DW is causing a problem.  Hmm... We need another way to pass segment
infos around consistently. 

> Improve how IndexWriter flushes deletes against existing segments
> -----------------------------------------------------------------
>
>                 Key: LUCENE-2680
>                 URL: https://issues.apache.org/jira/browse/LUCENE-2680
>             Project: Lucene - Java
>          Issue Type: Improvement
>            Reporter: Michael McCandless
>             Fix For: 4.0
>
>         Attachments: LUCENE-2680.patch, LUCENE-2680.patch, LUCENE-2680.patch, LUCENE-2680.patch,
LUCENE-2680.patch, LUCENE-2680.patch, LUCENE-2680.patch, LUCENE-2680.patch, LUCENE-2680.patch
>
>
> IndexWriter buffers up all deletes (by Term and Query) and only
> applies them if 1) commit or NRT getReader() is called, or 2) a merge
> is about to kickoff.
> We do this because, for a large index, it's very costly to open a
> SegmentReader for every segment in the index.  So we defer as long as
> we can.  We do it just before merge so that the merge can eliminate
> the deleted docs.
> But, most merges are small, yet in a big index we apply deletes to all
> of the segments, which is really very wasteful.
> Instead, we should only apply the buffered deletes to the segments
> that are about to be merged, and keep the buffer around for the
> remaining segments.
> I think it's not so hard to do; we'd have to have generations of
> pending deletions, because the newly merged segment doesn't need the
> same buffered deletions applied again.  So every time a merge kicks
> off, we pinch off the current set of buffered deletions, open a new
> set (the next generation), and record which segment was created as of
> which generation.
> This should be a very sizable gain for large indices that mix
> deletes, though, less so in flex since opening the terms index is much
> faster.

-- 
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-unsubscribe@lucene.apache.org
For additional commands, e-mail: dev-help@lucene.apache.org


Mime
View raw message