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====== MG======

MG is a freely-available full-text retrieval system that makes efficient use of disk resources by storing the index, and the text that is indexed, in compressed form. The MG system is described in the eponymous book [[http://people.eng.unimelb.edu.au/ammoffat/mg/|Managing Gigabytes]]. To meet the needs of The New Zealand Digital Library and the [[http://ww.greenstone.org|Greenstone]] software we have made a number of improvements to the standard MG distribution. These improvements are being made available as MG-1.3. September 1999.

MG-1.3 offers:

**Flexible stemming methods**\\
Different stemming methods can be used in the same collection. In the original version a collection could only use a single stemming method, now all four combinations of stemming and casefolding can be used in queries. This can be applied to whole queries as well as individual words. 
    
**Weighting terms**\\
Weightings can be applied to individual terms in a ranked query. This allows a user to influence the order that documents are returned with documents with the higher rated words nearer the top. 
    
**Term frequencies**\\
The number of times each query term appears in the collection can be displayed during a query. 

**Decompression of text**\\
A small program is included in the distribution which allows you to decompress all the text with the document and paragraph breaks inserted at all the right places. With minimal programming you could then rebuild the collection from the compressed text. 
    
**Merging of level 3 indexes**\\
In the original version merging indexes was only implemented for level 2 indexes. We have extended this to also include level 3 indexes. 
    
**Machine independent indexes**\\
The indexes are now always written using network byte ordering, which is big endian. This means that indexes built on little endian machines can be used on big endian machines providing the two machines have data types the same length and use the same floating point formats. 
    
**Port to MSDOS**\\
A port of MG to MSDOS with 32 bit processing has also been incorporated into the distribution. This port allows MG to be compiled on 32 bit Windows platforms. 


====Installing MG-1.3====

**Installing on Unix systems**

  * Download the [[http://www.nzdl.org/download/mg/mg-1.3g.tar.gz|MG-1.3g]] distribution.
  * Change your current working directory to where the distribution was unpacked and run:
<code>./configure --prefix=`pwd`
make
make install</code>

**Installing on Microsoft Windows systems**

  * Download the [[http://www.nzdl.org/download/mg/mg-1.3g.tar.gz|MG-1.3g]] distribution.
  * Change your current working directory to where the distribution was unpacked and run:
<code>nmake /f win32.mak
nmake /f win32.mak install</code>


====Bugs====

Please report problems specific to MG-1.3 to the [[mailto:greenstone-users@list.waikato.ac.nz|Greenstone mailing list]].