turbonss/deps/cmph/docs/newslog.html

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2018-12-29 03:53:09 +02:00
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<H1>News Log</H1>
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<H2>News for version 1.1</H2>
<P>
Fixed a bug in the chd_pc algorithm and reorganized tests.
</P>
<H2>News for version 1.0</H2>
<P>
This is a bugfix only version, after which a revamp of the cmph code and
algorithms will be done.
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<H2>News for version 0.9</H2>
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<LI><A HREF="chd.html">The CHD algorithm</A>, which is an algorithm that can be tuned to generate MPHFs that require approximately 2.07 bits per key to be stored. The algorithm outperforms <A HREF="bdz.html">the BDZ algorithm</A> and therefore is the fastest one available in the literature for sets that can be treated in internal memory.
<LI><A HREF="chd.html">The CHD_PH algorithm</A>, which is an algorithm to generate PHFs with load factor up to <I>99 %</I>. It is actually the CHD algorithm without the ranking step. If we set the load factor to <I>81 %</I>, which is the maximum that can be obtained with <A HREF="bdz.html">the BDZ algorithm</A>, the resulting functions can be stored in <I>1.40</I> bits per key. The space requirement increases with the load factor.
<LI>All reported bugs and suggestions have been corrected and included as well.
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<H2>News for version 0.8</H2>
<UL>
<LI><A HREF="bdz.html">An algorithm to generate MPHFs that require around 2.6 bits per key to be stored</A>, which is referred to as BDZ algorithm. The algorithm is the fastest one available in the literature for sets that can be treated in internal memory.
<LI><A HREF="bdz.html">An algorithm to generate PHFs with range m = cn, for c &gt; 1.22</A>, which is referred to as BDZ_PH algorithm. It is actually the BDZ algorithm without the ranking step. The resulting functions can be stored in 1.95 bits per key for <I>c = 1.23</I> and are considerably faster than the MPHFs generated by the BDZ algorithm.
<LI>An adapter to support a vector of struct as the source of keys has been added.
<LI>An API to support the ability of packing a perfect hash function into a preallocated contiguous memory space. The computation of a packed function is still faster and can be easily mmapped.
<LI>The hash functions djb2, fnv and sdbm were removed because they do not use random seeds and therefore are not useful for MPHFs algorithms.
<LI>All reported bugs and suggestions have been corrected and included as well.
</UL>
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<H2>News for version 0.7</H2>
<UL>
<LI>Added man pages and a pkgconfig file.
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<H2>News for version 0.6</H2>
<UL>
<LI><A HREF="fch.html">An algorithm to generate MPHFs that require less than 4 bits per key to be stored</A>, which is referred to as FCH algorithm. The algorithm is only efficient for small sets.
<LI>The FCH algorithm is integrated with <A HREF="brz.html">BRZ algorithm</A> so that you will be able to efficiently generate space-efficient MPHFs for sets in the order of billion keys.
<LI>All reported bugs and suggestions have been corrected and included as well.
</UL>
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<H2>News for version 0.5</H2>
<UL>
<LI>A thread safe vector adapter has been added.
<LI><A HREF="brz.html">A new algorithm for sets in the order of billion of keys that requires approximately 8.1 bits per key to store the resulting MPHFs.</A>
<LI>All reported bugs and suggestions have been corrected and included as well.
</UL>
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<H2>News for version 0.4</H2>
<UL>
<LI>Vector Adapter has been added.
<LI>An optimized version of bmz (bmz8) for small set of keys (at most 256 keys) has been added.
<LI>All reported bugs and suggestions have been corrected and included as well.
</UL>
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<H2>News for version 0.3</H2>
<UL>
<LI>New heuristic added to the bmz algorithm permits to generate a mphf with only
<I>24.80n + O(1)</I> bytes. The resulting function can be stored in <I>3.72n</I> bytes.
<A HREF="bmz.html#heuristic">click here</A> for details.
</UL>
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<TABLE ALIGN="center" CELLPADDING="4">
<TR>
<TD><A HREF="index.html">Home</A></TD>
<TD><A HREF="chd.html">CHD</A></TD>
<TD><A HREF="bdz.html">BDZ</A></TD>
<TD><A HREF="bmz.html">BMZ</A></TD>
<TD><A HREF="chm.html">CHM</A></TD>
<TD><A HREF="brz.html">BRZ</A></TD>
<TD><A HREF="fch.html">FCH</A></TD>
</TR>
</TABLE>
<HR NOSHADE SIZE=1>
<P>
Enjoy!
</P>
<P>
<A HREF="mailto:davi@users.sourceforge.net">Davi de Castro Reis</A>
</P>
<P>
<A HREF="mailto:db8192@users.sourceforge.net">Djamel Belazzougui</A>
</P>
<P>
<A HREF="mailto:fc_botelho@users.sourceforge.net">Fabiano Cupertino Botelho</A>
</P>
<P>
<A HREF="mailto:nivio@dcc.ufmg.br">Nivio Ziviani</A>
</P>
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