X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=doc%2Fadministration.xml;h=de01bd56ff2f9085921ee81b369b07cd27ec4647;hb=53f91ef0ea7d588a26e90bf87ad46bdb84938d6f;hp=fe3a49c3a84b92ef243cdeaa9a86d56192dfd4c9;hpb=47054fae00306e75212a26ee5305f00032c99001;p=idzebra-moved-to-github.git diff --git a/doc/administration.xml b/doc/administration.xml index fe3a49c..de01bd5 100644 --- a/doc/administration.xml +++ b/doc/administration.xml @@ -1,5 +1,5 @@ - + Administrating Zebra - - Those are in the zebra config file enabled by a directive like (use - only one of these a time!): + Dynamic ranking is enabled by a directive like one of the + following in the zebra config file (use only one of these a time!): - rank: rank-1 # default - rank: rank-static # dummy - rank: zvrank # TDF-IDF like + rank: rank-1 # default TDF-IDF like + rank: rank-static # dummy do-nothing - Notice that the rank-1 and - zvrank do not use the static rank + Notice that the rank-1 algorithm + does not use the static rank information in the list keys, and will produce the same ordering - with our without static ranking enabled. + with or without static ranking enabled. The dummy rank-static reranking/scoring function returns just score = max int - staticrank - in order to preserve the ordering of hit sets with and without it's - call. - Obviously, to combine static and dynamic ranking usefully, one wants + in order to preserve the static ordering of hit sets that would + have been produced had it not been invoked. + Obviously, to combine static and dynamic ranking usefully, + it is necessary to make a new ranking - function, which is left + function; this is left as an exercise for the reader. - + + + + Dynamic ranking is done at query time rather than + indexing time (this is why we + call it ``dynamic ranking'' in the first place ...) + It is invoked by adding + the Bib-1 relation attribute with + value ``relevance'' to the PQF query (that is, + @attr 2=102, see also + + The BIB-1 Attribute Set Semantics). + To find all articles with the word Eoraptor in + the title, and present them relevance ranked, issue the PQF query: + + @attr 2=102 @attr 1=4 Eoraptor + + + + + The default rank-1 ranking module implements a + TF-IDF (Term Frequecy over Inverse Document Frequency) like algorithm. + + + + + Notice that dynamic ranking is not compatible + with estimated hit sizes, as all documents in + a hit set must be acessed to compute the correct placing in a + ranking sorted list. Therefore the use attribute setting + @attr 2=102 clashes with + @attr 9=integer. + + + + + It is possible to apply dynamic ranking on only parts of the PQF query: + + @and @attr 2=102 @attr 1=1010 Utah @attr 1=1018 Springer + + searches for all documents which have the term 'Utah' on the + body of text, and which have the term 'Springer' in the publisher + field, and sort them in the order of the relvance ranking made on + the body-of-text index only. + + + Ranking weights may be used to pass a value to a ranking + algorithm, using the non-standard BIB-1 attribute type 9. + This allows one branch of a query to use one value while + another branch uses a different one. For example, we can search + for utah in the title index with weight 30, as + well as in the ``any'' index with weight 20: + + @attr 2=102 @or @attr 9=30 @attr 1=4 utah @attr 9=20 utah + + + + + The ranking-weight feature is experimental. It may change in future + releases of zebra, and is not production mature. + + + + + Notice that dynamic ranking can be enabled in sever side CQL + query expansion by adding @attr 2=102 to + the CQL config file. For example + + relationModifier.relevant = 2=102 + + invokes dynamic ranking each time a CQL query of the form + + Z> querytype cql + Z> f alvis.text =/relevant house + + is issued. Dynamic ranking can also be automatically used on + specific CQL indexes by (for example) setting + + index.alvis.text = 1=text 2=102 + + which then invokes dynamic ranking each time a CQL query of the form + + Z> querytype cql + Z> f alvis.text = house + + is issued. + + + + + + + Sorting + + Zebra sorts efficiently using special sorting indexes + (type=s; so each sortable index must be known + at indexing time, specified in the configuration of record + indexing. For example, to enable sorting according to the BIB-1 + Date/time-added-to-db field, one could add the line + + xelm /*/@created Date/time-added-to-db:s + + to any .abs record-indexing configuration file. + Similarily, one could add an indexing element of the form + + + + ]]> + to any alvis-filter indexing stylesheet. + + + Indexing can be specified at searching time using a query term + carrying the non-standard + BIB-1 attribute-type 7. This removes the + need to send a Z39.50 Sort Request + separately, and can dramatically improve latency when the client + and server are on separate networks. + The sorting part of the query is separate from the rest of the + query - the actual search specification - and must be combined + with it using OR. + + + A sorting subquery needs two attributes: an index (such as a + BIB-1 type-1 attribute) specifying which index to sort on, and a + type-7 attribute whose value is be 1 for + ascending sorting, or 2 for descending. The + term associated with the sorting attribute is the priority of + the sort key, where 0 specifies the primary + sort key, 1 the secondary sort key, and so + on. + + For example, a search for water, sort by title (ascending), + is expressed by the PQF query + + @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 + + whereas a search for water, sort by title ascending, + then date descending would be + + @or @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 @attr 7=2 @attr 1=30 1 + + + + Notice the fundamental differences between dynamic + ranking and sorting: there can be + only one ranking function defined and configured; but multiple + sorting indexes can be specified dynamically at search + time. Ranking does not need to use specific indexes, so + dynamic ranking can be enabled and disabled without + re-indexing; whereas, sorting indexes need to be + defined before indexing. + + + + + @@ -1256,9 +1443,17 @@ - - +