Hi,
here is a concrete example.
I am starting with an index that has 19017236 docs, which takes 58989 Mb
on disk:
21.07.2011 15:21 20 segments.gen
21.07.2011 15:21 2'974 segments_2acy4
21.07.2011 13:58 0 write.lock
16.07.2011 02:21 33'445'798'886 _52aho.fdt
16.07.2011 02:21 178'723'932 _52aho.fdx
16.07.2011 01:58 5'002 _52aho.fnm
16.07.2011 03:10 9'857'410'889 _52aho.frq
16.07.2011 03:10 4'538'234'846 _52aho.prx
16.07.2011 03:10 61'581'767 _52aho.tii
16.07.2011 03:10 5'505'039'790 _52aho.tis
21.07.2011 01:01 1'899'536 _52aho_5.del
21.07.2011 01:05 4'222'206'034 _6t61z.fdt
21.07.2011 01:05 21'424'556 _6t61z.fdx
21.07.2011 01:01 5'002 _6t61z.fnm
21.07.2011 01:12 1'170'370'187 _6t61z.frq
21.07.2011 01:12 598'373'388 _6t61z.prx
21.07.2011 01:12 7'574'912 _6t61z.tii
21.07.2011 01:12 678'766'206 _6t61z.tis
21.07.2011 13:46 1'458'592'058 _7d6me.cfs
21.07.2011 13:48 15'702'654 _7dhgz.cfs
21.07.2011 13:52 16'800'942 _7dphm.cfs
21.07.2011 13:55 16'714'431 _7dxht.cfs
21.07.2011 14:24 17'505'435 _7e0wz.cfs
21.07.2011 14:24 5'875'852 _7e0xu.cfs
21.07.2011 14:48 18'340'470 _7e1x5.cfs
21.07.2011 15:19 16'978'564 _7e3ck.cfs
21.07.2011 15:21 1'208'656 _7e3hv.cfs
21.07.2011 15:21 19'361 _7e3hw.cfs
28 File(s) 61'855'156'350 bytes
I am doing a delete of some of the older documents. after the delete, I
commit then I optimize down to 2 segments. at the end of the optimize the
index contains 18702510 docs (314727 were deleted) and it takes now 58975
Mb on disk:
21.07.2011 15:37 20 segments.gen
21.07.2011 15:37 524 segments_2acy6
21.07.2011 13:58 0 write.lock
16.07.2011 02:21 33'445'798'886 _52aho.fdt
16.07.2011 02:21 178'723'932 _52aho.fdx
16.07.2011 01:58 5'002 _52aho.fnm
16.07.2011 03:10 9'857'410'889 _52aho.frq
16.07.2011 03:10 4'538'234'846 _52aho.prx
16.07.2011 03:10 61'581'767 _52aho.tii
16.07.2011 03:10 5'505'039'790 _52aho.tis
21.07.2011 15:23 1'999'945 _52aho_6.del
21.07.2011 15:31 5'194'848'138 _7e3hy.fdt
21.07.2011 15:31 28'613'668 _7e3hy.fdx
21.07.2011 15:25 5'002 _7e3hy.fnm
21.07.2011 15:37 1'529'771'296 _7e3hy.frq
21.07.2011 15:37 726'582'244 _7e3hy.prx
21.07.2011 15:37 8'518'198 _7e3hy.tii
21.07.2011 15:37 763'213'144 _7e3hy.tis
18 File(s) 61'840'347'291 bytes
as you can see, size on disk did not really change. at this point I
optimize down to 1 segment and at the end the index takes 48273 Mb on
disk:
21.07.2011 16:46 20 segments.gen
21.07.2011 16:46 278 segments_2acy8
21.07.2011 13:58 0 write.lock
21.07.2011 16:06 32'901'423'750 _7e3hz.fdt
21.07.2011 16:06 149'582'052 _7e3hz.fdx
21.07.2011 15:42 5'002 _7e3hz.fnm
21.07.2011 16:46 8'608'541'177 _7e3hz.frq
21.07.2011 16:46 4'392'616'115 _7e3hz.prx
21.07.2011 16:46 50'571'856 _7e3hz.tii
21.07.2011 16:46 4'515'914'658 _7e3hz.tis
10 File(s) 50'618'654'908 bytes
this means that with the 1 segment optimize I was able to reclaim 10 Gb on
disk that the 2 segments optimize could not achieve.
how can this be explained? is that a normal behavior?
thanks,
vince
Simon Willnauer <simon.willna...@googlemail.com>
20.07.2011 23:11
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java-user@lucene.apache.org
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Subject
Re: optimize with num segments > 1 index keeps growing
On Wed, Jul 20, 2011 at 2:00 PM, <v.se...@lombardodier.com> wrote:
> Hi,
>
> I index several millions small documents per day. each day, I remove
some
> of the older documents to keep the index at a stable number of
documents.
> after each purge, I commit then I optimize the index. what I found is
that
> if I keep optimizing with max num segments = 2, then the index keeps
> growing on the disk. but as soon as I optimize with just 1 segment, the
> space gets reclaimed on the disk. so, I have currently adopted the
> following strategy : every night I optimize with 2 segments, except once
> per week where I optimize with just 1 segment.
what do you mean by keeps growing. you have n segments and you
optimize down to 2 and the index is bigger than the one with n
segments?
simon
>
> is that an expected behavior?
> I guess I am doing something special because I was not able to reproduce
> this behavior in a unit test. what could it be?
>
> it would be nice to get some explanatory services within the product to
> help get some understanding on its behavior. something that tells you
some
> information about your index for instance (number of docs in the
different
> states, how the space is being used, ...). lucene is a wonderful
product,
> but to me this is almost like black magic, and when there is a specific
> behavior, I have got little clues to figure out something by myself.
some
> user oriented logging would be nice as well (the index writer info
stream
> is really verbose and very low level).
>
> thanks for your help,
>
>
> Vince
>
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