X-Git-Url: http://git.indexdata.com/?a=blobdiff_plain;f=doc%2Fquerymodel.xml;h=3a3f781364c18f34d8ca197c1453277728869fb9;hb=7253cbefce93c35a083505e14d97b3ae24c0a66b;hp=bbadb28fe1ecac3fb65b89bba520a7239512e175;hpb=37dc985516f52f34fc8434cc8beb982bb0c8988f;p=idzebra-moved-to-github.git diff --git a/doc/querymodel.xml b/doc/querymodel.xml index bbadb28..3a3f781 100644 --- a/doc/querymodel.xml +++ b/doc/querymodel.xml @@ -1,5 +1,5 @@ - + Query Model
@@ -41,7 +41,7 @@ parties developing Z39.50 software, and is often referred to as Prefix Query Notation, or in short PQN. See - for further explanations and + for further explanations and descriptions of Zebra's capabilities.
@@ -144,8 +144,8 @@ -
- Prefix Query Format syntax and semantics +
+ RPN queries and semantics The PQF grammar is documented in the YAZ manual, and shall not be @@ -155,10 +155,10 @@ query parse tree. -
- PQF tree structure +
+ RPN tree structure - The PQF parse tree - or the equivalent textual representation - + The RPN parse tree - or the equivalent textual representation in PQF - may start with one specification of the attribute set used. Following is a query tree, which @@ -184,7 +184,7 @@ Attribute set - Short hand + PQF notation (Short hand) Status Notes @@ -192,7 +192,7 @@ - Explain + Explain exp-1 Special attribute set used on the special automagic IR-Explain-1 database to gain information on @@ -201,24 +201,24 @@ predefined - Bib1 + Bib-1 bib-1 Standard PQF query language attribute set which defines the semantics of Z39.50 searching. In addition, all of the - non-use attributes (types 2-11) define the hard-wired + non-use attributes (types 2-12) define the hard-wired Zebra internal query processing. default - GILS + GILS gils - Extension to the Bib1 attribute set. + Extension to the Bib-1 attribute set. predefined + + + Experimental. Do not use in production code. + + -
- Zebra Extension Approximative Limit Attribute (type 11) +
+ + + +
+ Local Approximative Limit Attribute (type 11) - Zebra computes - unless otherwise configured - + Zebra computes - unless otherwise configured - the exact hit count for every APT (leaf) in the query tree. These hit counts are returned as part of the searchResult-1 facility in the binary encoded Z39.50 search @@ -1654,45 +1694,36 @@ Do not use approximative hit count limits in conjunction with relevance ranking, as re-sorting of the - result set obviosly only works when the entire result set has + result set only works when the entire result set has been processed. - - - This facility clashes with rank weight, because there all - documents in the hit lists need to be examined for scoring and - re-sorting. - It is an experimental - extension. Do not use in production code. - -
-
- Zebra Extension Term Reference Attribute (type 10) +
+ Global Approximative Limit Attribute (type 12) - Zebra supports the searchResult-1 facility. - If the Term Reference Attribute (type 10) is - given, that specifies a subqueryId value returned as part of the - search result. It is a way for a client to name an APT part of a - query. + By default Zebra computes precise hit counts for a query as + a whole. Setting attribute 12 makes it perform approximative + hit counts instead. It has the same semantics as + estimatehits for the . - + The attribute (12) can occur anywhere in the query tree. + Unlike regular attributes it does not relate to the leaf (APT) + - but to the whole query. + - Experimental. Do not use in production code. - + Do not use approximative hit count limits + in conjunction with relevance ranking, as re-sorting of the + result set only works when the entire result set has + been processed. + -
+
-
Zebra specific Scan Extensions to all Attribute Sets @@ -1765,11 +1796,12 @@ - - - Experimental. Do not use in production code. - - + + Zebra 2.0.2 and later is able to skip 0 hit counts. This, however, + is known not to scale if the number of terms to skip is high. + This most likely will happen if the result set is small (and + result in many 0 hits). +
@@ -1779,17 +1811,6 @@ enable approximate hit counts for scan hit counts, in the same way as for search hit counts. - - - - Experimental and buggy. Definitely not to be used in production code. - -
@@ -2475,19 +2496,17 @@ Exhaustive information can be found in the Section "Specification of CQL to RPN mappings" in the YAZ manual. - - http://www.indexdata.dk/yaz/doc/tools.tkl#tools.cql.map, - and shall therefore not be repeated here. + , + and shall therefore not be repeated here.