<chapter id="architecture">
- <!-- $Id: architecture.xml,v 1.13 2006-09-22 12:34:45 adam Exp $ -->
+ <!-- $Id: architecture.xml,v 1.14 2006-11-24 13:05:11 adam Exp $ -->
<title>Overview of Zebra Architecture</title>
-
<section id="architecture-representation">
<title>Local Representation</title>
</para>
</section>
+ <section id="default-idx-zebra">
+ <title>Retrieval of Zebra internal record data</title>
+ <para>
+ Starting with <literal>Zebra</literal> version 2.0.5 or newer, it is
+ possible to use a special element set which has the prefix
+ <literal>zebra::</literal>.
+ </para>
+ <para>
+ Using this element will, regardless of record type, return
+ Zebra's internal index structure/data for a record.
+ In particular, the regular record filters are not invoked when
+ these are in use.
+ This can in some cases make the retrival faster than regular
+ retrieval operations (for MARC, XML etc).
+ </para>
+ <table id="special-retrieval">
+ <title>Special Retrieval Elements</title>
+ <tgroup cols="2">
+ <thead>
+ <row>
+ <entry>Element Set</entry>
+ <entry>Description</entry>
+ <entry>Syntax</entry>
+ </row>
+ </thead>
+ <tbody>
+ <row>
+ <entry><literal>zebra::meta::sysno</literal></entry>
+ <entry>Get Zebra record system ID</entry>
+ <entry>XML and SUTRS</entry>
+ </row>
+ <row>
+ <entry><literal>zebra::data</literal></entry>
+ <entry>Get raw record</entry>
+ <entry>all</entry>
+ </row>
+ <row>
+ <entry><literal>zebra::meta</literal></entry>
+ <entry>Get Zebra record internal metadata</entry>
+ <entry>XML and SUTRS</entry>
+ </row>
+ <row>
+ <entry><literal>zebra::index</literal></entry>
+ <entry>Get all indexed keys for record</entry>
+ <entry>XML and SUTRS</entry>
+ </row>
+ <row>
+ <entry>
+ <literal>zebra::index::</literal><replaceable>f</replaceable>
+ </entry>
+ <entry>
+ Get indexed keys for field <replaceable>f</replaceable> of record
+ </entry>
+ <entry>XML and SUTRS</entry>
+ </row>
+ <row>
+ <entry>
+ <literal>zebra::index::</literal><replaceable>field</replaceable>:<replaceable>t</replaceable>
+ </entry>
+ <entry>
+ Get indexed keys for field <replaceable>f</replaceable>
+ and type <replaceable>t</replaceable> of record
+ </entry>
+ <entry>XML and SUTRS</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ <para>
+ For example, to fetch the raw binary record data stored in the
+ zebra internal storage, or on the filesystem, the following
+ commands can be issued:
+ <screen>
+ Z> f @attr 1=title my
+ Z> format xml
+ Z> elements zebra::data
+ Z> s 1+1
+ Z> format sutrs
+ Z> s 1+1
+ Z> format usmarc
+ Z> s 1+1
+ </screen>
+ </para>
+ <para>
+ The special
+ <literal>zebra::data</literal> element set name is
+ defined for any record syntax, but will always fetch
+ the raw record data in exactly the original form. No record syntax
+ specific transformations will be applied to the raw record data.
+ </para>
+ <para>
+ Also, Zebra internal metadata about the record can be accessed:
+ <screen>
+ Z> f @attr 1=title my
+ Z> format xml
+ Z> elements zebra::meta::sysno
+ Z> s 1+1
+ </screen>
+ displays in <literal>XML</literal> record syntax only internal
+ record system number, whereas
+ <screen>
+ Z> f @attr 1=title my
+ Z> format xml
+ Z> elements zebra::meta
+ Z> s 1+1
+ </screen>
+ displays all available metadata on the record. These include sytem
+ number, database name, indexed filename, filter used for indexing,
+ score and static ranking information and finally bytesize of record.
+ </para>
+ <para>
+ Sometimes, it is very hard to figure out what exactly has been
+ indexed how and in which indexes. Using the indexing stylesheet of
+ the Alvis filter, one can at least see which portion of the record
+ went into which index, but a similar aid does not exist for all
+ other indexing filters.
+ </para>
+ <para>
+ The special
+ <literal>zebra::index</literal> element set names are provided to
+ access information on per record indexed fields. For example, the
+ queries
+ <screen>
+ Z> f @attr 1=title my
+ Z> format sutrs
+ Z> elements zebra::index
+ Z> s 1+1
+ </screen>
+ will display all indexed tokens from all indexed fields of the
+ first record, and it will display in <literal>SUTRS</literal>
+ record syntax, whereas
+ <screen>
+ Z> f @attr 1=title my
+ Z> format xml
+ Z> elements zebra::index::title
+ Z> s 1+1
+ Z> elements zebra::index::title:p
+ Z> s 1+1
+ </screen>
+ displays in <literal>XML</literal> record syntax only the content
+ of the zebra string index <literal>title</literal>, or
+ even only the type <literal>p</literal> phrase indexed part of it.
+ </para>
+ <note>
+ <para>
+ Trying to access numeric <literal>Bib-1</literal> use
+ attributes or trying to access non-existent zebra intern string
+ access points will result in a Diagnostic 25: Specified element set
+ 'name not valid for specified database.
+ </para>
+ </note>
+ </section>
+
</chapter>
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