[
https://issues.apache.org/jira/browse/LUCENE-2680?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Jason Rutherglen updated LUCENE-2680:
-------------------------------------
Attachment: LUCENE-2680.patch
In my head at least I think the concurrency issues are worked
out in this patch. We're not taking into account recency of
deletes as I'm not sure it matters. DW applyDeletesToSegments
takes care of the coalescing of segment deletes as this is a
synced DW method called by a synced IW method, meaning
nothing'll be changing anywhere, so we're good with the possible
concurrency issues. I'm still a little worried about concurrent
incoming deleted terms/queries, however those can't be added
until after a successful ADTS call due to the DW sync.
Guess it's time for the complete tests to run.
> 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
>
>
> 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-unsubscr...@lucene.apache.org
For additional commands, e-mail: dev-h...@lucene.apache.org
