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From Shai Erera <>
Subject Re: Why perform optimization in 'off hours'?
Date Mon, 31 Aug 2009 15:28:41 GMT
When you run optimize(), you consume CPU and do lots of IO operations which
can really mess up the OS IO cache. Optimize is a very heavy process and
therefore is recommended to run at off hours. Sometimes, when your index is
large enough, it's recommended to run it during weekends, since the
optimize() process itself may take several hours, so that a nightly job
won't be enough.


On Mon, Aug 31, 2009 at 6:25 PM, Ted Stockwell <> wrote:

> Hi All,
> I am new to Lucene and I was reading 'Lucene in Action' this weekend.
> The book recommends that optimization be performed when the index is not in
> use.
> The book makes it clear that optimization *may* be performed while indexing
> but it says that optimizing while indexing makes indexing slower.
> However, the book does not explain *why* indexing would be slower while
> optimizing.
> Since I know that optimization will create new segments and not mess with
> the old ones, I'm confused as to how optimizing may cause indexing to slow
> down.
> Any ideas?
> Thanks,
> ted stockwell
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