<chapter id="querymodel">
- <!-- $Id: querymodel.xml,v 1.3 2006-06-14 12:20:06 marc Exp $ -->
+ <!-- $Id: querymodel.xml,v 1.7 2006-06-16 10:30:12 marc Exp $ -->
<title>Query Model</title>
<sect1 id="querymodel-overview">
<title>Query Model Overview</title>
+
+ <sect2 id="querymodel-query-languages">
+ <title>Query Languages</title>
+
+ <para>
+ Zebra is born as a networking Information Retrieval engine adhering
+ to the international standards
+ <ulink url="&url.z39.50;">Z39.50</ulink> and
+ <ulink url="&url.sru;">SRU</ulink>,
+ and implement the query model defined there.
+ Unfortunately, the Z39.50 query model has only defined a binary
+ encoded representation, which is used as transport packaging in
+ the Z39.50 protocol layer. This representation is not human
+ readable, nor defines any convenient way to specify queries.
+ </para>
+ <!-- tell about RPN - include link to YAZ
+ url.yaz.pqf -->
+
+
+
+ <sect3 id="querymodel-query-languages-pqf">
+ <title>Prefix Query Format (PQF)</title>
+
<para>
- Zebra is born as a networking Information Retrieval engine adhering
- to the international standards
- <ulink url="&url.z39.50;">Z39.50</ulink> and
- <ulink url="&url.sru;">SRU</ulink>,
- and implement the query model defined there.
- Unfortunately, the Z39.50 query model has only defined a binary
- encoded representation, which is used as transport packaging in
- the Z39.50 protocol layer. This representation is not human
- readable, nor defines any convenient way to specify queries.
- </para>
- <para>
- Therefore, Index Data has defined a textual representaion in the
- <literal>Prefix Query Format</literal>, short
- <literal>PQF</literal>, which then has been adopted by other
- parties developing Z39.50 software. It is also often referred to as
- <literal>Prefix Query Notation</literal>, or in short
- <literal>PQN</literal>, and is thoroughly explained in
- <xref linkend="querymodel-pqf"/>.
- </para>
-
+ Index Data has defined a textual representaion in the
+ <literal>Prefix Query Format</literal>, short
+ <literal>PQF</literal>, which then has been adopted by other
+ parties developing Z39.50 software. It is also often referred to as
+ <literal>Prefix Query Notation</literal>, or in short
+ <literal>PQN</literal>, and is thoroughly explained in
+ <xref linkend="querymodel-pqf"/>.
+ </para>
+ </sect3>
+
+
+ <!-- PQF/RPN is natively supported. CQL is NOT . So we need a map -->
+ <sect3 id="querymodel-query-languages-cql">
+ <title>Common Query Language (CQL)</title>
<para>
- In addition, Zebra can be configured to understand and map the
- <literal>Common Query Language</literal>
- (<ulink url="&url.cql;">CQL</ulink>)
- to PQF. See an introduction on the mapping to the internal query
- representation in
- <xref linkend="querymodel-cql-to-pqf"/>.
- </para>
- </sect1>
+ In addition, Zebra can be configured to understand and map the
+ <literal>Common Query Language</literal>
+ (<ulink url="&url.cql;">CQL</ulink>)
+ to PQF. See an introduction on the mapping to the internal query
+ representation in
+ <xref linkend="querymodel-cql-to-pqf"/>.
+ </para>
+ </sect3>
+
+ </sect2>
+
+ <sect2 id="querymodel-query-types">
+ <title>Query types</title>
+ <para>
+ </para>
+
+ <sect3 id="querymodel-query-type-explain">
+ <title>Explain Queries</title>
+ <para>
+ </para>
+ </sect3>
+
+ <sect3 id="querymodel-query-type-search">
+ <title>Search Queries</title>
+ <para>
+ </para>
+ </sect3>
+
+ <sect3 id="querymodel-query-type-scan">
+ <title>Scan Queries</title>
+ <para>
+ </para>
+ </sect3>
+
+ </sect2>
+
+ </sect1>
+
<sect1 id="querymodel-pqf">
<title>Prefix Query Format structure and syntax</title>
may start with one specification of the
<emphasis>attribute set</emphasis> used. Following is a query
tree, which
- consists of <emphasis>atomic query parts</emphasis>, eventually
+ consists of <emphasis>atomic query parts (APT)</emphasis>, eventually
paired by <emphasis>boolean binary operators</emphasis>, and
finally <emphasis>recursively combined </emphasis> into
complex query trees.
<note>
The Zebra internal query procesing is modeled after
the <literal>Bib1</literal> attribute set, and the non-use
- attributes type 2-9 are hard-wired in. It is therefore essential
+ attributes type 2-6 are hard-wired in. It is therefore essential
to be familiar with <xref linkend="querymodel-bib1"/>.
</note>
</para>
- <table id="querymodel-attribute-sets-table">
+ <table id="querymodel-attribute-sets-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
<caption>Attribute sets predefined in Zebra</caption>
<!--
<thead>
-->
<tbody>
<tr>
- <td><emphasis>exp-1</emphasis></td>
+ <td><literal>exp-1</literal></td>
<td><literal>Explain</literal> attribute set</td>
<td>Special attribute set used on the special automagic
<literal>IR-Explain-1</literal> database to gain information on
and semantics.</td>
</tr>
<tr>
- <td><emphasis>bib-1</emphasis></td>
+ <td><literal>bib-1</literal></td>
<td><literal>Bib1</literal> attribute set</td>
<td>Standard PQF query language attribute set which defines the
semantics of Z39.50 searching. In addition, all of the
processing</td>
</tr>
<tr>
- <td><emphasis>gils</emphasis></td>
+ <td><literal>gils</literal></td>
<td><literal>GILS</literal> attribute set</td>
<td>Extention to the <literal>Bib1</literal> attribute set.</td>
</tr>
using the standard boolean operators into new query trees.
</para>
- <table id="querymodel-boolean-operators-table">
+ <table id="querymodel-boolean-operators-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
<caption>Boolean operators</caption>
<!--
<thead>
</thead>
-->
<tbody>
- <tr><td><emphasis>@and</emphasis></td>
+ <tr><td><literal>@and</literal></td>
<td>binary <literal>AND</literal> operator</td>
<td>Set intersection of two atomic queries hit sets</td>
</tr>
- <tr><td><emphasis>@or</emphasis></td>
+ <tr><td><literal>@or</literal></td>
<td>binary <literal>OR</literal> operator</td>
<td>Set union of two atomic queries hit sets</td>
</tr>
- <tr><td><emphasis>@not</emphasis></td>
+ <tr><td><literal>@not</literal></td>
<td>binary <literal>AND NOT</literal> operator</td>
<td>Set complement of two atomic queries hit sets</td>
</tr>
- <tr><td><emphasis>@prox</emphasis></td>
+ <tr><td><literal>@prox</literal></td>
<td>binary <literal>PROXIMY</literal> operator</td>
<td>Set intersection of two atomic queries hit sets. In
addition, the intersection set is purged for all
<sect3 id="querymodel-atomic-queries">
- <title>Atomic queries</title>
+ <title>Atomic queries (APT)</title>
<para>
Atomic queries are the query parts which work on one acess point
only. These consist of <literal>an attribute list</literal>
followed by a <literal>single term</literal> or a
- <literal>quoted term list</literal>.
+ <literal>quoted term list</literal>, and are often called
+ <emphasis>Attributes-Plus-Terms (APT)</emphasis> queries.
</para>
<para>
Unsupplied non-use attributes type 2-9 are either inherited from
See <xref linkend="querymodel-bib1"/> for details.
</para>
- <table id="querymodel-atomic-queries-table">
+ <table id="querymodel-atomic-queries-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
<caption>Atomic queries</caption>
<!--
<thead>
</screen>
</para>
<para>
- Equivalent query fully specified:
+ Equivalent query fully specified including all default values:
<screen>
Z> find @attrset bib-1 @attr 1=1017 @attr 2=3 @attr 3=3 @attr 4=1 @attr 5=100 @attr 6=1 "information"
</screen>
<sect3 id="querymodel-bib1-use">
- <title>Use Attributes (type = 1)</title>
+ <title>Use Attributes (type 1)</title>
</sect3>
<para>
+ A use attribute specifies an access point for any atomic query.
+ These acess points are highly dependent on the attribute set used
+ in the query, and are user configurable using the following
+ default configuration files:
+ <filename>tab/bib1.att</filename>,
+ <filename>tab/dan1.att</filename>,
+ <filename>tab/explain.att</filename>, and
+ <filename>tab/gils.att</filename>.
+ New attribute sets can be added by adding new
+ <filename>tab/*.att</filename> configuration files, which need to
+ be sourced in the main configuration <filename>zebra.cfg</filename>.
+ </para>
+
+ <para>
+ In addition, Zebra allows the acess of
+ <emphasis>internal index names</emphasis> and <emphasis>dynamic
+ XPath</emphasis> as use attributes.
+ See <xref linkend="querymodel-use-string"/> and
+ <xref linkend="querymodel-use-xpath"/> for
+ alternative acess to the Zebra internal index names and XPath queries.
+ </para>
+
+ <para>
Phrase search for <emphasis>information retrieval</emphasis> in
the title-register:
<screen>
<sect3 id="querymodel-bib1-relation">
- <title>Relation Attributes (type = 2)</title>
- </sect3>
+ <title>Relation Attributes (type 2)</title>
+
+ <para>
+ Relation attributes describe the relationship of the access
+ point (left side
+ of the relation) to the search term as qualified by the attributes (right
+ side of the relation), e.g., Date-publication <= 1975.
+ </para>
+
+ <table id="querymodel-bib1-relation-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
+ <caption>Relation Attributes (type 2)</caption>
+ <thead>
+ <tr>
+ <td>Relation</td>
+ <td>Value</td>
+ <td>Notes</td>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td> Less than</td>
+ <td>1</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Less than or equal</td>
+ <td>2</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Equal</td>
+ <td>3</td>
+ <td>default</td>
+ </tr>
+ <tr>
+ <td>Greater or equal</td>
+ <td>4</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Greater than</td>
+ <td>5</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Not equal</td>
+ <td>6</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Phonetic</td>
+ <td>100</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Stem</td>
+ <td>101</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Relevance</td>
+ <td>102</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>AlwaysMatches</td>
+ <td>103</td>
+ <td>unsupported</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <para>
+ The relation attribute
+ <literal>relevance (102)</literal> is supported, see
+ <xref linkend="administration-ranking"/> for full information.
+ <!-- always-matches (103) not supported for all indexes -->
+ </para>
+
<para>
+ All ordering operations are based on a lexicographical ordering,
+ <emphasis>expect</emphasis> when the
+ <literal>structure attribute numeric (109)</literal> is used. In
+ this case, ordering is numerical. See
+ <xref linkend="querymodel-bib1-structure"/>.
</para>
- <para>
+ <para>
Ranked search for <emphasis>information retrieval</emphasis> in
- the title-register
- (see <xref linkend="administration-ranking"/> for the glory details):
+ the title-register:
<screen>
Z> find @attr 1=4 @attr 2=102 "information retrieval"
</screen>
</para>
-
+ </sect3>
+
<sect3 id="querymodel-bib1-position">
- <title>Position Attributes (type = 3)</title>
+ <title>Position Attributes (type 3)</title>
+
+ <para>
+ The position attribute specifies the location of the search term
+ within the field or subfield in which it appears.
+ </para>
+
+ <table id="querymodel-bib1-position-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
+ <caption>Position Attributes (type 3)</caption>
+ <thead>
+ <tr>
+ <td>Position</td>
+ <td>Value</td>
+ <td>Notes</td>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td>First in field </td>
+ <td>1</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>First in subfield</td>
+ <td>2</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Any position in field</td>
+ <td>3</td>
+ <td>default</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <para>
+ The position attribute values <literal>first in field (1)</literal>,
+ and <literal>first in subfield(2)</literal> are unsupported.
+ Using them does not trigger an error, but silent defaults to
+ <literal>any position in field (3)</literal>.
+ <!-- It should -->
+ </para>
</sect3>
<sect3 id="querymodel-bib1-structure">
- <title>Structure Attributes (type = 4)</title>
+ <title>Structure Attributes (type 4)</title>
+
+ <para>
+ The structure attribute specifies the type of search
+ term. This causes the search to be mapped on
+ different Zebra internal indexes, which must have been defined
+ at index time.
+ </para>
+
+ <para>
+ The possible values of the
+ <literal>structure attribute (type 4)</literal> can be defined
+ using the configuraiton file <filename>
+ tab/default.idx</filename>.
+ The default configuration is summerized in this table.
+ </para>
+
+ <table id="querymodel-bib1-structure-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
+ <caption>Structure Attributes (type 4)</caption>
+ <thead>
+ <tr>
+ <td>Structure</td>
+ <td>Value</td>
+ <td>Notes</td>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td>Phrase </td>
+ <td>1</td>
+ <td>default</td>
+ </tr>
+ <tr>
+ <td>Word</td>
+ <td>2</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Key</td>
+ <td>3</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Year</td>
+ <td>4</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Date (normalized)</td>
+ <td>5</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Word list</td>
+ <td>6</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Date (un-normalized)</td>
+ <td>100</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Name (normalized) </td>
+ <td>101</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Name (un-normalized) </td>
+ <td>102</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Structure</td>
+ <td>103</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Urx</td>
+ <td>104</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Free-form-text</td>
+ <td>105</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Document-text</td>
+ <td>106</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Local-number</td>
+ <td>107</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>String</td>
+ <td>108</td>
+ <td>unsupported</td>
+ </tr>
+ <tr>
+ <td>Numeric string</td>
+ <td>109</td>
+ <td>supported</td>
+ </tr>
+ </tbody>
+ </table>
</sect3>
+ <para>
+ The structure attribute value <literal>local-number
+ (107)</literal>
+ is supported, and maps always to the Zebra internal document ID.
+ </para>
<para>
For example, in
<sect3 id="querymodel-bib1-truncation">
<title>Truncation Attributes (type = 5)</title>
+
+ <para>
+ The truncation attribute specifies whether variations of one or
+ more characters are allowed between serch term and hit terms, or
+ not. Using non-default truncation attributes will broaden the
+ document hit set of a search query.
+ </para>
+
+ <table id="querymodel-bib1-truncation-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
+ <caption>Truncation Attributes (type 5)</caption>
+ <thead>
+ <tr>
+ <td>Truncation</td>
+ <td>Value</td>
+ <td>Notes</td>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td>Right truncation </td>
+ <td>1</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Left truncation</td>
+ <td>2</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Left and right truncation</td>
+ <td>3</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>Do not truncate</td>
+ <td>100</td>
+ <td>default</td>
+ </tr>
+ <tr>
+ <td>Process # in search term</td>
+ <td>101</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>RegExpr-1 </td>
+ <td>102</td>
+ <td>supported</td>
+ </tr>
+ <tr>
+ <td>RegExpr-2</td>
+ <td>103</td>
+ <td>supported</td>
+ </tr>
+ </tbody>
+ </table>
+
+ <para>
+ Truncation attribute value
+ <literal>Process # in search term (100)</literal> is a
+ poor-man's regular expression search. It maps
+ each <literal>#</literal> to <literal>.*</literal>, and
+ performes then a <literal>Regexp-1 (102)</literal> regular
+ expression search.
+ </para>
+ <para>
+ Truncation attribute value
+ <literal>Regexp-1 (102)</literal> is a normal regular search,
+ see.
+ </para>
+ <para>
+ Truncation attribute value
+ <literal>Regexp-2 (103) </literal> is a Zebra specific extention
+ which allows <emphasis>fuzzy</emphasis> matches. One single
+ error in spelling of search terms is allowed, i.e., a document
+ is hit if it includes a term which can be mapped to the used
+ search term by one character substitution, addition, deletion or
+ change of posiiton.
+ </para>
+ <!--
+ Special 104, 105, 106 are deprecated and will be removed! -->
</sect3>
<sect3 id="querymodel-bib1-completeness">
<title>Completeness Attributes (type = 6)</title>
+ <para>
+ This attribute is ONLY used if structure w, p is to be
+ chosen. completeness is ignorned if not w, p is to be
+ used..
+ Incomplete field(1) is the default and makes Zebra use
+ register type w.
+ complete subfield(2) and complete field(3) both triggers
+ search field type p.
+ </para>
</sect3>
</sect2>
set used in a <literal>search</literal> operation query.
</para>
- <table id="querymodel-zebra-attr-search-table">
+ <table id="querymodel-zebra-attr-search-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
<caption>Zebra Search Attribute Extentions</caption>
<thead>
<tr>
- <td><emphasis>Name and Type</emphasis></td>
+ <td>Name</td>
+ <td>Value</td>
<td>Operation</td>
<td>Zebra version</td>
</tr>
</thead>
<tbody>
<tr>
- <td><emphasis>Embedded Sort (type 7)</emphasis></td>
+ <td>Embedded Sort</td>
+ <td>7</td>
<td>search</td>
<td>1.1</td>
</tr>
<tr>
- <td><emphasis>Term Set (type 8)</emphasis></td>
+ <td>Term Set</td>
+ <td>8</td>
<td>search</td>
<td>1.1</td>
</tr>
<tr>
- <td><emphasis>Rank weight (type 9)</emphasis></td>
+ <td>Rank Weight</td>
+ <td>9</td>
<td>search</td>
<td>1.1</td>
</tr>
<tr>
- <td><emphasis>Approx Limit (type 9)</emphasis></td>
+ <td>Approx Limit</td>
+ <td>9</td>
<td>search</td>
<td>1.4</td>
</tr>
<tr>
- <td><emphasis>Term Reference (type 10)</emphasis></td>
+ <td>Term Reference</td>
+ <td>10</td>
<td>search</td>
<td>1.4</td>
</tr>
<title>Zebra Extention Term Reference Attribute (type 10)</title>
</sect3>
<para>
- Zebra supports the searchResult-1 facility. If attribute 10 is
+ Zebra supports the <literal>searchResult-1</literal> facility.
+ If the <literal>Term Reference Attribute (type 10)</literal> 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.
recognized regardless of attribute
set used in a <literal>scan</literal> operation query.
</para>
- <table id="querymodel-zebra-attr-scan-table">
+ <table id="querymodel-zebra-attr-scan-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
<caption>Zebra Scan Attribute Extentions</caption>
<thead>
<tr>
- <td><emphasis>Name and Type</emphasis></td>
+ <td>Name</td>
+ <td>Type</td>
<td>Operation</td>
<td>Zebra version</td>
</tr>
</thead>
<tbody>
<tr>
- <td><emphasis>Result Set Narrow (type 8)</emphasis></td>
+ <td>Result Set Narrow</td>
+ <td>8</td>
<td>scan</td>
<td>1.3</td>
</tr>
<tr>
- <td><emphasis>Approximative Limit (type 9)</emphasis></td>
+ <td>Approximative Limit</td>
+ <td>9</td>
<td>scan</td>
<td>1.4</td>
</tr>
</tbody>
</table>
- <sect3 id="querymodel-zebra-attr-xyz">
+ <sect3 id="querymodel-zebra-attr-narrow">
<title>Zebra Extention Result Set Narrow (type 8)</title>
</sect3>
<para>
- If attribute 8 is given for scan, the value is the name of a
- result set. Each hit count in scan is @and'ed with the result set
- given.
+ If attribute <literal>Result Set Narrow (type 8)</literal>
+ is given for <literal>scan</literal>, the value is the name of a
+ result set. Each hit count in <literal>scan</literal> is
+ <literal>@and</literal>'ed with the result set given.
</para>
<!--
<para>
Experimental and buggy. Definitely not to be used in production code.
</warning>
- <sect3 id="querymodel-zebra-attr-xyz">
+ <sect3 id="querymodel-zebra-attr-approx">
<title>Zebra Extention Approximative Limit (type 9)</title>
</sect3>
<para>
- The approximative limit (as for search) is a way to enable approx
- hit counts for scan hit counts.
+ The <literal>Zebra Extention Approximative Limit (type
+ 9)</literal> is a way to enable approx
+ hit counts for <literal>scan</literal> hit counts, in the same
+ way as for <literal>search</literal> hit counts.
</para>
<!--
<para>
Both query types follow the same syntax with the operands:
</para>
- <table id="querymodel-regular-operands-table">
+ <table id="querymodel-regular-operands-table"
+ frame="all" rowsep="1" colsep="1" align="center">
+
<caption>Regular Expression Operands</caption>
<!--
<thead>
-->
<tbody>
<tr>
- <td><emphasis>x</emphasis></td>
- <td>Matches the character <emphasis>x</emphasis>.</td>
+ <td><literal>x</literal></td>
+ <td>Matches the character <literal>x</literal>.</td>
</tr>
<tr>
- <td><emphasis>.</emphasis></td>
+ <td><literal>.</literal></td>
<td>Matches any character.</td>
</tr>
<tr>
- <td><emphasis>[ .. ]</emphasis></td>
+ <td><literal>[ .. ]</literal></td>
<td>Matches the set of characters specified;
such as <literal>[abc]</literal> or <literal>[a-c]</literal>.</td>
</tr>
The above operands can be combined with the following operators:
</para>
-
- <table id="querymodel-regular-operators-table">
+ <table id="querymodel-regular-operators-table"
+ frame="all" rowsep="1" colsep="1" align="center">
<caption>Regular Expression Operators</caption>
<!--
<thead>
-->
<tbody>
<tr>
- <td><emphasis>x*</emphasis></td>
- <td>Matches <emphasis>x</emphasis> zero or more times.
+ <td><literal>x*</literal></td>
+ <td>Matches <literal>x</literal> zero or more times.
Priority: high.</td>
</tr>
<tr>
- <td><emphasis>x+</emphasis></td>
- <td>Matches <emphasis>x</emphasis> one or more times.
+ <td><literal>x+</literal></td>
+ <td>Matches <literal>x</literal> one or more times.
Priority: high.</td>
</tr>
<tr>
- <td><emphasis>x?</emphasis></td>
- <td> Matches <emphasis>x</emphasis> zero or once.
+ <td><literal>x?</literal></td>
+ <td> Matches <literal>x</literal> zero or once.
Priority: high.</td>
</tr>
<tr>
- <td><emphasis>xy</emphasis></td>
- <td> Matches <emphasis>x</emphasis>, then <emphasis>y</emphasis>.
+ <td><literal>xy</literal></td>
+ <td> Matches <literal>x</literal>, then <literal>y</literal>.
Priority: medium.</td>
</tr>
<tr>
- <td><emphasis>x|y</emphasis></td>
- <td> Matches either <emphasis>x</emphasis> or <emphasis>y</emphasis>.
+ <td><literal>x|y</literal></td>
+ <td> Matches either <literal>x</literal> or <literal>y</literal>.
Priority: low.</td>
</tr>
<tr>
- <td><emphasis>( )</emphasis></td>
+ <td><literal>( )</literal></td>
<td>The order of evaluation may be changed by using parentheses.</td>
</tr>
</tbody>
</table>
-
+
<para>
- If the first character of the <emphasis>Regxp-2</emphasis> query
+ If the first character of the <literal>Regxp-2</literal> query
is a plus character (<literal>+</literal>) it marks the
beginning of a section with non-standard specifiers.
The next plus character marks the end of the section.
<para>
Combinations with other attributes are possible. For example, a
- ranked search with a regular expression
- (see <xref linkend="administration-ranking"/> for the glory details):
+ ranked search with a regular expression:
<screen>
Z> find @attr 1=4 @attr 5=102 @attr 2=102 "informat.* retrieval"
</screen>
process input records.
Two basic types of processing are available - raw text and structured
data. Raw text is just that, and it is selected by providing the
- argument <emphasis>text</emphasis> to Zebra. Structured records are
+ argument <literal>text</literal> to Zebra. Structured records are
all handled internally using the basic mechanisms described in the
subsequent sections.
Zebra can read structured records in many different formats.