<chapter id="querymodel">
- <!-- $Id: querymodel.xml,v 1.25 2006-09-03 21:37:26 adam Exp $ -->
+ <!-- $Id: querymodel.xml,v 1.26 2006-09-22 12:34:45 adam Exp $ -->
<title>Query Model</title>
<section id="querymodel-overview">
parties developing Z39.50 software, and is often referred to as
<emphasis>Prefix Query Notation</emphasis>, or in short
PQN. See
- <xref linkend="querymodel-pqf"/> for further explanations and
+ <xref linkend="querymodel-rpn"/> for further explanations and
descriptions of Zebra's capabilities.
</para>
</section>
</section>
- <section id="querymodel-pqf">
- <title>Prefix Query Format syntax and semantics</title>
+ <section id="querymodel-rpn">
+ <title>RPN queries and semantics</title>
<para>
The <ulink url="&url.yaz.pqf;">PQF grammar</ulink>
is documented in the YAZ manual, and shall not be
query parse tree.
</para>
- <section id="querymodel-pqf-tree">
- <title>PQF tree structure</title>
+ <section id="querymodel-rpn-tree">
+ <title>RPN tree structure</title>
<para>
- 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
<emphasis>attribute set</emphasis> used. Following is a query
tree, which
<thead>
<row>
<entry>Attribute set</entry>
- <entry>Short hand</entry>
+ <entry>PQF notation (Short hand)</entry>
<entry>Status</entry>
<entry>Notes</entry>
</row>
<tbody>
<row>
- <entry><literal>Explain</literal></entry>
+ <entry>Explain</entry>
<entry><literal>exp-1</literal></entry>
<entry>Special attribute set used on the special automagic
<literal>IR-Explain-1</literal> database to gain information on
<entry>predefined</entry>
</row>
<row>
- <entry><literal>Bib1</literal></entry>
+ <entry>Bib-1</entry>
<entry><literal>bib-1</literal></entry>
<entry>Standard PQF query language attribute set which defines the
semantics of Z39.50 searching. In addition, all of the
<entry>default</entry>
</row>
<row>
- <entry><literal>GILS</literal></entry>
+ <entry>GILS</entry>
<entry><literal>gils</literal></entry>
- <entry>Extension to the <literal>Bib1</literal> attribute set.</entry>
+ <entry>Extension to the Bib-1 attribute set.</entry>
<entry>predefined</entry>
</row>
<!--
<row>
- <entry><literal>IDXPATH</literal></entry>
+ <entry>IDXPATH</entry>
<entry><literal>idxpath</literal></entry>
<entry>Hardwired XPATH like attribute set, only available for
indexing with the GRS record model</entry>
<note>
<para>
The Zebra internal query processing is modeled after
- the <literal>Bib1</literal> attribute set, and the non-use
+ the Bib-1 attribute set, and the non-use
attributes type 2-6 are hard-wired in. It is therefore essential
to be familiar with <xref linkend="querymodel-bib1-nonuse"/>.
</para>
</thead>
<tbody>
<row><entry><literal>@and</literal></entry>
- <entry>binary <literal>AND</literal> operator</entry>
+ <entry>binary AND operator</entry>
<entry>Set intersection of two atomic queries hit sets</entry>
</row>
<row><entry><literal>@or</literal></entry>
- <entry>binary <literal>OR</literal> operator</entry>
+ <entry>binary OR operator</entry>
<entry>Set union of two atomic queries hit sets</entry>
</row>
<row><entry><literal>@not</literal></entry>
- <entry>binary <literal>AND NOT</literal> operator</entry>
+ <entry>binary AND NOT operator</entry>
<entry>Set complement of two atomic queries hit sets</entry>
</row>
<row><entry><literal>@prox</literal></entry>
- <entry>binary <literal>PROXIMITY</literal> operator</entry>
+ <entry>binary PROXIMITY operator</entry>
<entry>Set intersection of two atomic queries hit sets. In
addition, the intersection set is purged for all
documents which do not satisfy the requested query
<title>Atomic queries (APT)</title>
<para>
Atomic queries are the query parts which work on one access point
- only. These consist of <literal>an attribute list</literal>
- followed by a <literal>single term</literal> or a
- <literal>quoted term list</literal>, and are often called
+ only. These consist of <emphasis>an attribute list</emphasis>
+ followed by a <emphasis>single term</emphasis> or a
+ <emphasis>quoted term list</emphasis>, and are often called
<emphasis>Attributes-Plus-Terms (APT)</emphasis> queries.
</para>
<para>
<tbody>
<row>
<entry><emphasis>attribute list</emphasis></entry>
- <entry>List of <literal>orthogonal</literal> attributes</entry>
+ <entry>List of <emphasis>orthogonal</emphasis> attributes</entry>
<entry>Any of the orthogonal attribute types may be omitted,
these are inherited from higher query tree nodes, or if not
inherited, are set to the default Zebra configuration values.
</row>
<row>
<entry><emphasis>term</emphasis></entry>
- <entry>single <literal>term</literal>
- or <literal>quoted term list</literal> </entry>
+ <entry>single <emphasis>term</emphasis>
+ or <emphasis>quoted term list</emphasis> </entry>
<entry>Here the search terms or list of search terms is added
to the query</entry>
</row>
</para>
<para>
- The <literal>scan</literal> operation is only supported with
+ The <emphasis>scan</emphasis> operation is only supported with
atomic APT queries, as it is bound to one access point at a
time. Boolean query trees are not allowed during
- <literal>scan</literal>.
+ <emphasis>scan</emphasis>.
</para>
<para>
<para>
Defining a named result set and re-using it in the next query,
- using <literal>yaz-client</literal>. Notice that the client, not
- the server, assigns the string <literal>'1'</literal> to the
+ using <application>yaz-client</application>. Notice that the client, not
+ the server, assigns the string '1' to the
named result set.
<screen>
Z> f @attr 1=4 mozart
<section id="querymodel-use-string">
<title>Zebra's special access point of type 'string'</title>
<para>
- The numeric <literal>use (type 1)</literal> attribute is usually
+ The numeric <emphasis>use (type 1)</emphasis> attribute is usually
referred to from a given
attribute set. In addition, Zebra let you use
<emphasis>any internal index
As we have seen above, it is possible (albeit seldom a great
idea) to emulate
<ulink url="http://www.w3.org/TR/xpath">XPath 1.0</ulink> based
- search by defining <literal>use (type 1)</literal>
+ search by defining <emphasis>use (type 1)</emphasis>
<emphasis>string</emphasis> attributes which in appearance
<emphasis>resemble XPath queries</emphasis>. There are two
problems with this approach: first, the XPath-look-alike has to
than it pretends to access.
</para>
<para>
- When using the <literal>GRS Record Model</literal>
+ When using the GRS Record Model
(see <xref linkend="grs"/>), we have the
possibility to embed <emphasis>life</emphasis>
XPath expressions
in the PQF queries, which are here called
- <literal>use (type 1)</literal> <emphasis>xpath</emphasis>
+ <emphasis>use (type 1)</emphasis> <emphasis>xpath</emphasis>
attributes. You must enable the
<literal>xpath enable</literal> directive in your
<literal>.abs</literal> configuration files.
<para>
The Z39.50 standard defines the
<ulink url="&url.z39.50.explain;">Explain</ulink> attribute set
- <literal>Exp-1</literal>, which is used to discover information
+ Exp-1, which is used to discover information
about a server's search semantics and functional capabilities
Zebra exposes a "classic"
Explain database by base name <literal>IR-Explain-1</literal>, which
</para>
<para>
The attribute-set <literal>exp-1</literal> consists of a single
- <literal>use attribute (type 1)</literal>.
+ use attribute (type 1).
</para>
<para>
In addition, the non-Use
- <literal>bib-1</literal> attributes, that is, the types
- <literal>Relation</literal>, <literal>Position</literal>,
- <literal>Structure</literal>, <literal>Truncation</literal>,
- and <literal>Completeness</literal> are imported from
- the <literal>bib-1</literal> attribute set, and may be used
+ Bib-1 attributes, that is, the types
+ <emphasis>Relation</emphasis>, <emphasis>Position</emphasis>,
+ <emphasis>Structure</emphasis>, <emphasis>Truncation</emphasis>,
+ and <emphasis>Completeness</emphasis> are imported from
+ the Bib-1 attribute set, and may be used
within any explain query.
</para>
</section>
<section id="querymodel-bib1">
- <title>Bib1 Attribute Set</title>
+ <title>Bib-1 Attribute Set</title>
<para>
Most of the information contained in this section is an excerpt of
- the <literal>ATTRIBUTE SET BIB-1 (Z39.50-1995)
- SEMANTICS</literal>,
- found at <ulink url="&url.z39.50.attset.bib1.1995;">. The BIB-1
+ the ATTRIBUTE SET BIB-1 (Z39.50-1995) SEMANTICS
+ found at <ulink url="&url.z39.50.attset.bib1.1995;">. The Bib-1
Attribute Set Semantics</ulink> from 1995, also in an updated
<ulink url="&url.z39.50.attset.bib1;">Bib-1
Attribute Set</ulink>
<filename>tab/gils.att</filename>.
</para>
<para>
- For example, some few <literal>Bib-1</literal> use
+ For example, some few Bib-1 use
attributes from the <filename>tab/bib1.att</filename> are:
<screen>
att 1 Personal-name
<row>
<entry>AlwaysMatches</entry>
<entry>103</entry>
- <entry>supported</entry>
+ <entry>supported *</entry>
</row>
</tbody>
</tgroup>
</table>
+ <note>
+ <para>
+ AlwaysMatches searches are only supported if alwaysmatches indexing
+ has been enabled. See <xref linkend="default-idx-file"/>
+ </para>
+ </note>
<para>
The relation attributes 1-5 are supported and work exactly as
expected.
All ordering operations are based on a lexicographical ordering,
<emphasis>expect</emphasis> when the
- <literal>structure attribute numeric (109)</literal> is used. In
+ structure attribute numeric (109) is used. In
this case, ordering is numerical. See
<xref linkend="querymodel-bib1-structure"/>.
<screen>
<para>
The relation attribute
- <literal>Relevance (102)</literal> is supported, see
+ <emphasis>Relevance (102)</emphasis> is supported, see
<xref linkend="administration-ranking"/> for full information.
</para>
<para>
The relation attribute
- <literal>AlwaysMatches (103)</literal> is in the default
+ <emphasis>AlwaysMatches (103)</emphasis> is in the default
configuration
supported in conjecture with structure attribute
- <literal>Phrase (1)</literal> (which may be omitted by
+ <emphasis>Phrase (1)</emphasis> (which may be omitted by
default).
It can be configured to work with other structure attributes,
see the configuration file
<xref linkend="querymodel-pqf-apt-mapping"/>.
</para>
<para>
- <literal>AlwaysMatches (103)</literal> is a
+ <emphasis>AlwaysMatches (103)</emphasis> is a
great way to discover how many documents have been indexed in a
given field. The search term is ignored, but needed for correct
PQF syntax. An empty search term may be supplied.
<row>
<entry>First in field </entry>
<entry>1</entry>
- <entry>unsupported</entry>
+ <entry>supported *</entry>
</row>
<row>
<entry>First in subfield</entry>
<entry>2</entry>
- <entry>unsupported</entry>
+ <entry>supported *</entry>
</row>
<row>
<entry>Any position in field</entry>
<entry>3</entry>
- <entry>supported</entry>
+ <entry>default</entry>
</row>
</tbody>
</tgroup>
</table>
-
- <para>
- The position attribute values <literal>first in field (1)</literal>,
- and <literal>first in subfield(2)</literal> are unsupported.
- Using them silently maps to
- <literal>any position in field (3)</literal>. A proper diagnostic
- should have been issued.
+
+ <note>
+ <para>
+ Zebra only supports first-in-field seaches if the
+ <literal>firstinfield</literal> is enabled for the index
+ Refer to <xref linkend="default-idx-file"/>.
+ Zebra does not distinguish between first in field and
+ first in subfield. They result in the same hit count.
+ Searching for first position in (sub)field in only supported in Zebra
+ 2.0.2 and later.
</para>
+ </note>
</section>
<section id="querymodel-bib1-structure">
<section id="querymodel-zebra">
- <title>Advanced Zebra PQF Features</title>
+ <title>Extended Zebra RPN Features</title>
<para>
The Zebra internal query engine has been extended to specific needs
not covered by the <literal>bib-1</literal> attribute set query
<section id="querymodel-zebra-attr-search">
<title>Zebra specific Search Extensions to all Attribute Sets</title>
<para>
- Zebra extends the Bib1 attribute types, and these extensions are
+ Zebra extends the Bib-1 attribute types, and these extensions are
recognized regardless of attribute
set used in a <literal>search</literal> operation query.
</para>
</screen>
</para>
- <warning>
- <para>
- Experimental. Do not use in production code.
- </para>
- </warning>
+ <para>
+ 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).
+ </para>
</section>
<section id="querymodel-zebra-attr-approx">
enable approximate hit counts for scan hit counts, in the same
way as for search hit counts.
</para>
- <!--
- <para>
- <screen>
- </screen>
- </para>
- -->
- <warning>
- <para>
- Experimental and buggy. Definitely not to be used in production code.
- </para>
- </warning>
</section>
</section>
<para>
Exhaustive information can be found in the
Section "Specification of CQL to RPN mappings" in the YAZ manual.
- <ulink url="http://www.indexdata.dk/yaz/doc/tools.tkl#tools.cql.map">
- http://www.indexdata.dk/yaz/doc/tools.tkl#tools.cql.map</ulink>,
- and shall therefore not be repeated here.
+ <ulink url="&url.yaz.cql2pqf;"/>,
+ and shall therefore not be repeated here.
</para>
<!--
<para>
See
- <ulink url="http://www.loc.gov/z3950/agency/zing/cql/dc-indexes.html">
- http://www.loc.gov/z3950/agency/zing/cql/dc-indexes.html</ulink>
- for the Maintenance Agency's work-in-progress mapping of Dublin Core
+ <ulink url="http://www.loc.gov/z3950/agency/zing/cql/dc-indexes.html"/>
+ for the Maintenance Agency's work-in-progress mapping of Dublin Core
indexes to Attribute Architecture (util, XD and BIB-2)
- attributes.
- </para>
+ attributes.
+ </para>
-->
</section>
projects / idzebra-moved-to-github.git / blobdiff