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From Erick Erickson <>
Subject Re: Solr5 Optimize
Date Wed, 16 Mar 2016 16:56:47 GMT
In general, don't bother with optimize unless the index is quite static,
i.e. there are very few adds/updates or those updates are done in
batches and rarely (i.e. once a day or less frequently).

As far as space, this will require that you have at _least_ as much
free space on your disks as your index occupies. Shouldn't require
much in the way of RAM though.

Optimize, also referred to as "Force Merge" will merge all the segments
down to one, and in the process reclaim data from deleted (or updated)

The thing is, this is also accomplished by "background merging" which
happens automatically. Every time you do a hard commit, Lucene
figures out if any segments need to be merged and does that automatically.
During that process, any information associated with deleted docs is

The third video down here:
is Mikes visualization of the automatic merging process.


On Wed, Mar 16, 2016 at 9:40 AM, Rallavagu <> wrote:
> All,
> Solr 5.4 with emdbedded Jetty (4G heap)
> Trying to understand behavior of "optimize" operation if not run explicitly.
> What is the frequency at which this operation is run, what are the storage
> requirements and how do we schedule it? Any comments/pointers would greatly
> help.
> Thanks in advance

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