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From "Ning Li" <>
Subject Re: flushRamSegments possible perf improvement?
Date Thu, 19 Oct 2006 17:42:56 GMT
> I also don't know if there are any negative performance implications
> of merging segments with sizes an order of magnitude apart.
> It should be relatively easy to test different scenarios by
> manipulating mergeFactor and maxBufferedDocs at the right time.

I agree. In addition, it's not clear to me how much improvement this
will make for a large data set.

Flushing ram segments separately allows an application to see new
documents sooner. Those documents don't have to be merged with other
on-disk documents before being available for search.

Flushing ram segments separately also has the following benefits as
Yonik put down before committing LUCENE-672 (flushing ram segments
separately is one part of that commit):

- flushing all ram segments separately from disk segments allows more
efficient implementations of combination reader/writers (like buffered
deletes) because docids won't change from the flush alone (a merge is
needed to change ids)
- flushing all buffered docs together leaves more optimization
possibilities... something other than single-doc segments could be
used to buffer in-mem docs in the future.

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