I guess I don't see the difference...

You need the write lock to use the indexWriter, and you also need the write lock to perform a deletion, so if you just get the write lock you can perform the deletion and the add, then close the writer.

I have asked how this submission optimizes anything, and I still can't seem to get an answer?


On Jul 6, 2006, at 4:27 PM, Otis Gospodnetic wrote:

I think that patch is for a different scenario, the one where you can't wait to batch deletes and adds, and want/need to execute them more frequently and in order they really are happening, without grouping them.

Otis

----- Original Message ----
From: robert engels <[EMAIL PROTECTED]>
To: java-dev@lucene.apache.org
Sent: Thursday, July 6, 2006 3:24:13 PM
Subject: Re: [jira] Commented: (LUCENE-565) Supporting deleteDocuments in IndexWriter (Code and Performance Results Provided)

I guess we just chose a much simpler way to do this...

Even with you code changes, to see the modification made using the
IndexWriter, it must be closed, and a new IndexReader opened.

So a far simpler way is to get the collection of updates first, then

using opened indexreader,
for each doc in collection
       delete document using "key"
endfor

open indexwriter
for each doc in collection
       add document
endfor

open indexreader


I don't see how your way is any faster. You must always flush to disk
and open the indexreader to see the changes.



On Jul 6, 2006, at 2:07 PM, Ning Li wrote:

Hi Otis and Robert,

I added an overview of my changes in JIRA. Hope that helps.

Anyway, my test did exercise the small batches, in that in our
incremental updates we delete the documents with the unique term, and
then add the new (which is what I assumed this was improving), and I
saw o appreciable difference.

Robert, could you describe a bit more how your test is set up? Or a
short
code snippet will help me explain.

Without the patch, when inserts and deletes are interleaved in small
batches, the performance can degrade dramatically because the
ramDirectory
is flushed to disk whenever an IndexWriter is closed, causing a lot of
small segments to be created on disk, which eventually need to be
merged.

Is this how your test is set up? And, what are the maxBufferedDocs
and the
maxBufferedDeleteTerms in your test? You won't see a performance
improvement
if they are about the same as the small batch size. The patch works by
internally buffering inserts and deletes into larger batches.

Regards,
Ning


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