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From Michael McCandless <luc...@mikemccandless.com>
Subject Re: Searching while optimizing
Date Tue, 24 Nov 2009 09:59:55 GMT
On Tue, Nov 24, 2009 at 1:44 AM, vsevel <v.sevel@lombardodier.com> wrote:
>
> 1) correct: I am using IndexWriter.getReader(). I guess I was assuming that
> was a privately owned object and I had no business dealing with its
> lifecycle. the api would be clearer to rename the operation createReader().

I just committed an addition to the javadocs that the caller is
responsible for closing the returned reader.

I think createReader() isn't great either because it sound more
expensive than it is -- under the hood, the returned reader is
typically sharing many subreaders with the last reader obtained.  That
sharing is what makes the reopen time fast.

> 2) how much transient disk space should I expect? isn't this pretty much
> what the index writer javadoc said we should not do: "When running in this
> mode, be careful not to refresh your readers while optimize or segment
> merges are taking place as this can tie up substantial disk space."

It is exactly what the javadoc says you should not do, but if you know
the risks, go for it ;)

How much space is tied up depends on how often you reopen and how
quickly you close the last reader.  If eg you aggressively close the
last reader, such that effectively only one reader is open at once,
then I think you're looking at worst case index consumes 4X it's
"nominal" size (vs 3X if you don't open a single reader).

Mike

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