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From: "Sascha Janz" <Sascha.Janz@gmx.net>
To: java-user@lucene.apache.org
Subject: =?UTF-8?Q?Aw=3A_RE=3A_=E5=9B=9E=E5=A4=8D=EF=BC=9A_Never_clo?=
 =?UTF-8?Q?se_IndexWriter/Reader=3F?=
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Date: Tue, 6 May 2014 10:35:45 +0200
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In-Reply-To: <004801cf6775$764917d0$62db4770$@thetaphi.de>
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Hello,
=20
many thanks to your answers.  i modified our sources to leave the IndexWri=
ter open. Also we changed the commit strategy. may be we will do commit onl=
y at night. We used to create own IndexReader for search. Now we changed th=
is using SearcherManager which performs quite well.

=20

We have an Index of nearly 50 GB. I am very curious how it will perform af=
ter the changes. may it will be like unlocking a handbrake. i hope so.

=20
Sascha

ps Uwe: i will be at your jax session next week.
=C2=A0
=C2=A0

Gesendet:=C2=A0Sonntag, 04. Mai 2014 um 10:47 Uhr
Von:=C2=A0"Uwe Schindler" <uwe@thetaphi.de>
An:=C2=A0java-user@lucene.apache.org
Betreff:=C2=A0RE: =E5=9B=9E=E5=A4=8D=EF=BC=9A Never close IndexWriter/Read=
er?
Hi,

I would not do that. Reopening the NRT reader is not as expensive as commi=
tting (which also fsyncs), but the current indexed data has to be written t=
o a new segment on disk (called flush in Lucene world). So reopenening peri=
odically is the better approach (unless you have really seldom accesses lik=
e one query per 1 minute). E.g., Elasticsearch reopens, by default, periodi=
cally every second.

Uwe

-----
Uwe Schindler
H.-H.-Meier-Allee 63, D-28213 Bremen
http://www.thetaphi.de
eMail: uwe@thetaphi.de

> -----Original Message-----
> From: 308181687 [mailto:308181687@qq.com]
> Sent: Sunday, May 04, 2014 6:05 AM
> To: java-user
> Subject: =E5=9B=9E=E5=A4=8D=EF=BC=9A Never close IndexWriter/Reader?
>
> Hi, Mike. Instead of periodically reopen NRT reader , I open/close it fo=
r every
> search query , will this result in performance issue?
>
>
> Thanks
> lubin
>
>
>
>
> ------------------ =E5=8E=9F=E5=A7=8B=E9=82=AE=E4=BB=B6 ----------------=
--
> =E5=8F=91=E4=BB=B6=E4=BA=BA: "Michael McCandless";<lucene@mikemccandless=
.com>;
> =E5=8F=91=E9=80=81=E6=97=B6=E9=97=B4: 2014=E5=B9=B45=E6=9C=884=E6=97=A5(=
=E6=98=9F=E6=9C=9F=E5=A4=A9) =E5=87=8C=E6=99=A81:43
> =E6=94=B6=E4=BB=B6=E4=BA=BA: "Lucene Users"<java-user@lucene.apache.org>=
;
>
> =E4=B8=BB=E9=A2=98: Re: Never close IndexWriter/Reader?
>
>
>
> Just leave your IW open forever and periodically reopen your NRT
> reader. Be sure you close your old NRT reader after opening a new
> one; SearcherManager makes this easy when multiple threads are using
> the readers.
>
> Committing every 200 docs seems quite frequent: commit is very costly,
> and it's only needed for recovery (so you know which docs are in the
> index if the machine/OS crashes).
>
> Mike McCandless
>
> http://blog.mikemccandless.com[http://blog.mikemccandless.com]
>
>
> On Sat, May 3, 2014 at 11:46 AM, Sascha Janz <sascha.janz@gmx.net> wrote=
:
> > Hi,
> >
> >
> >
> > We use lucene 4.6, our application receives continuously new documents=
.
> > Mostly emails. We need the update near real time, so we open the
> IndexReader
> > with Directory.open and IndexWriter.
> >
> >
> >
> > Periodically we do a commit, e.g. every 200 documents.
> >
> >
> >
> > We used to close the IndexWriter on commit, and then open a new one. I
> read
> > in documentation this is quite expensive, tests also showed me this. S=
o we
> > think about to only commit the IndexWriter and leave it open. So when
> should
> > we close the IndexWriter? I think about to leave it open and only clos=
e it,
> > when the server is shutting down. Is this a good idea? Any suggestions=
 or
> > comments? Would be nice J
> >
> >
> >
> > Greetings
> >
> > Sascha
> >
>
> ---------------------------------------------------------------------
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> For additional commands, e-mail: java-user-help@lucene.apache.org
>
> .


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