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https://github.com/yacy/yacy_search_server.git
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1a8a134e0c
The result should be a less usage of new String() and less memory usage (since a String-encapsulated byte[] has 40 bytes overhead) git-svn-id: https://svn.berlios.de/svnroot/repos/yacy/trunk@6815 6c8d7289-2bf4-0310-a012-ef5d649a1542
75 lines
3.2 KiB
Java
Executable File
75 lines
3.2 KiB
Java
Executable File
// PartitionScheme.java
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// ------------------------------
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// part of YaCy
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// (C) 2009 by Michael Peter Christen; mc@yacy.net
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// first published on http://yacy.net
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// Frankfurt, Germany, 28.01.2009
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//
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// $LastChangedDate: 2009-01-23 16:32:27 +0100 (Fr, 23 Jan 2009) $
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// $LastChangedRevision: 5514 $
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// $LastChangedBy: orbiter $
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//
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 2 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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package de.anomic.yacy.dht;
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import de.anomic.yacy.yacySeed;
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/**
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* A PartitionScheme is a calculation of index storage positions in the network of peers.
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* Depending on the size of the network and the requirements of use cases the network
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* may be defined in different ways. A search network can be constructed in two different ways:
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* * partition by document
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* * partition by word
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* Both schemes have different advances and disadvantages:
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* A partition by document has the following properties:
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* + all documents are distinct from each other, no double occurrences of documents and document infos
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* + good performance scaling up to about 100 peers
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* + no index distribution necessary
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* - not good scaling for a very large number of peers (1000+ servers cannot be requested simulanously)
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* A partition by word has the following properties:
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* + can scale for a very large number of peers
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* + can almost unlimited scale in number of documents because the number of peers may scale to really large numbers
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* + in case of a search only a very small number of peers must be asked
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* - double occurrences of documents cannot be avoided very easy
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* - index distribution is necessary and is IO and bandwidth-intensive
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* - a search request does not scale good, because so many references are accumulated at a single peer
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* The partition by word may be enhanced: a vertical scaling provides a better scaling for search,
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* but increases further the complexity of the distribution process.
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*
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* In YaCy we implement a word partition with vertical scaling. To organize the complexity of the
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* index distribution and peers selection in case of a search request, this interface is needed to
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* implement different distribution schemes.
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*
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* @author Michael Christen
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*
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*/
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public interface PartitionScheme {
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public int verticalPartitions();
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public long dhtPosition(final byte[] wordHash, final String urlHash);
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public long dhtPosition(final byte[] wordHash, final int verticalPosition);
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public int verticalPosition(final byte[] urlHash);
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public long[] dhtPositions(final byte[] wordHash);
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public long dhtDistance(final byte[] word, final String urlHash, final yacySeed peer);
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}
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