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From Mark Miller <markrmil...@gmail.com>
Subject Re: How much disk space does optimize really take
Date Wed, 07 Oct 2009 19:31:27 GMT
I can't tell why calling a commit or restarting is going to help
anything - or why you need more than 2x in any case. The only reason i
can see this being is if you have turned on auto-commit. Otherwise the
Reader is *always* only referencing what would have to be around anyway.

Your likely to just too close to the edge. There are fragmentation
issues and whatnot when your dealing with such large files and so little
space above what you need.

Phillip Farber wrote:
> Wow, this is weird.  I commit before I optimize.  In fact, I bounce
> tomcat before I optimize just in case. It makse sense, as you say,
> that then "the open reader can only be holding references to segments
> that wouldn't be deleted until the optimize is complete anyway".
>
> But we're still exceeding 2x. And after the optimize fails, if we then
> do a commit or bounce tomcat, a bunch of segments disappear. I am
> stumped.
>
> Yonik Seeley wrote:
>> On Wed, Oct 7, 2009 at 1:50 PM, Phillip Farber <pfarber@umich.edu>
>> wrote:
>>> So this implies that for a "normal" optimize, in every case, due to the
>>> Searcher holding open the existing segment prior to optimize that we'd
>>> always need 3x even in the normal case.
>>>
>>> This seems wrong since it is repeated stated that in the normal case
>>> only 2x
>>> is needed and I have successfully optimized a similar sized 192G
>>> index on
>>> identical hardware with a 400G capacity.
>>
>> 2x for the IndexWriter only.
>> Having an open index reader can increase that somewhat... 3x is the
>> absolute worst case I think and that can currently be avoided by first
>> calling commit and then calling optimize I think.  This way the open
>> reader will only be holding references to segments that wouldn't be
>> deleted until the optimize is complete anyway.
>>
>>
>> -Yonik
>> http://www.lucidimagination.com


-- 
- Mark

http://www.lucidimagination.com




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