From java-user-return-16841-apmail-lucene-java-user-archive=lucene.apache.org@lucene.apache.org Tue Oct 11 07:25:45 2005 Return-Path: Delivered-To: apmail-lucene-java-user-archive@www.apache.org Received: (qmail 71965 invoked from network); 11 Oct 2005 07:25:45 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (209.237.227.199) by minotaur.apache.org with SMTP; 11 Oct 2005 07:25:45 -0000 Received: (qmail 52454 invoked by uid 500); 11 Oct 2005 07:25:41 -0000 Delivered-To: apmail-lucene-java-user-archive@lucene.apache.org Received: (qmail 52421 invoked by uid 500); 11 Oct 2005 07:25:41 -0000 Mailing-List: contact java-user-help@lucene.apache.org; run by ezmlm Precedence: bulk List-Help: List-Unsubscribe: List-Post: List-Id: Reply-To: java-user@lucene.apache.org Delivered-To: mailing list java-user@lucene.apache.org Received: (qmail 52410 invoked by uid 99); 11 Oct 2005 07:25:41 -0000 Received: from asf.osuosl.org (HELO asf.osuosl.org) (140.211.166.49) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 11 Oct 2005 00:25:41 -0700 X-ASF-Spam-Status: No, hits=0.0 required=10.0 tests= X-Spam-Check-By: apache.org Received-SPF: pass (asf.osuosl.org: local policy) Received: from [203.181.105.76] (HELO hfep10.dion.ne.jp) (203.181.105.76) by apache.org (qpsmtpd/0.29) with ESMTP; Tue, 11 Oct 2005 00:25:43 -0700 Received: from sekiguchi2 ([58.5.235.18]) by hfep10.dion.ne.jp with SMTP id <20051011072518411.QXHP@hfep10.dion.ne.jp> for ; Tue, 11 Oct 2005 16:25:18 +0900 Message-ID: <01ed01c5ce34$ee374cf0$a000a8c0@sekiguchi2> From: "Koji Sekiguchi" To: References: <200510110916.03843.paul.elschot@xs4all.nl> Subject: Re: What is MMapDirectory? Date: Tue, 11 Oct 2005 16:25:17 +0900 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-2022-jp"; reply-type=original Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.2180 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 X-Virus-Checked: Checked by ClamAV on apache.org X-Spam-Rating: minotaur.apache.org 1.6.2 0/1000/N Paul, Thank you very much for your explanation. > However, in case you have different experience, we'd like to know. I don't have it. I'm just curious. Thank you again, Koji ----- Original Message ----- From: "Paul Elschot" To: Sent: Tuesday, October 11, 2005 4:16 PM Subject: Re: What is MMapDirectory? > Koji, > > On Sunday 09 October 2005 14:12, Koji Sekiguchi wrote: >> Hello, >> >> What is MMapDirectory? >> >> I've searched mailing list archive, but cannot find it. >> I could find the following explanation at Lucene 1.9 CHANGES.txt: >> >> 8. Add MMapDirectory, which uses nio to mmap input files. This is >> still somewhat slower than FSDirectory. However it uses less >> memory per query term, since a new buffer is not allocated per >> term, which may help applications which use, e.g., wildcard >> queries. It may also someday be faster. (cutting & Paul Elschot) >> >> And I saw bug 31508: >> >> [PATCH] MMapDirectory for huge index files >> http://issues.apache.org/bugzilla/show_bug.cgi?id=31508 > > Bugzilla has been replaced by JIRA recently, this is now here: > http://issues.apache.org/jira/browse/LUCENE-283 > >> >> But I'm curious to know about MMapDirecotry in more detail about >> the following point: >> >> 1. Were there any troubles in FSDirectory with huge index files? > > There were some troubles with huge index files, but not in FSDirectory. > FSDirectory is still faster than MMapDirectory, but that might change > in the future. > >> 2. Is MMapDirectory used for only searching? (not indexing?) > > Indeed so. > >> 3. Why is MMapDirectory somewhat slower than FSDirectory? >> 4. Why does MMapDirectory use less memory while using mapped file (mmap)? > > Both depend on the underlying implementation of buffering in the JVM > and in the operating system. In my (few) attempts so far, memory > mapped I/O does not currently help to improve performance of Lucene. > However, in case you have different experience, we'd like to know. > > Regards, > Paul Elschot > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org > For additional commands, e-mail: java-user-help@lucene.apache.org > > --------------------------------------------------------------------- To unsubscribe, e-mail: java-user-unsubscribe@lucene.apache.org For additional commands, e-mail: java-user-help@lucene.apache.org