Release 3 (8.1.7)
Part Number A86030-01
 Library |
 Product |
 Contents |
 Index |
| Oracle8i Application Developer's Guide - XML Release 3 (8.1.7) Part Number A86030-01 |
|
Using interMedia Text to Search and Retrieve Data from XML Documents, 10 of 22
The CTX_DDL PL/SQL supplied package creates and manages the objects required for interMedia Text indexes. The detailed list of CTX_DDL package's stored procedures and functions can be found in Oracle8i interMedia Text Reference. Use the CTXAPP role when executing the CTX_DDL package.
The following CTX_DDL procedures are used in this chapter:
If you are uncertain which role to use with the CTX packages, run the following script. This lists the roles required for each CTX package:
connect ctxsys/ctxsys column "Package" format a15 column "Role needed to execute Package" format a30 select dba_objects.object_name "Package", dba_tab_privs.grantee "Role needed to execute Package" from dba_objects, dba_tab_privs where dba_objects.object_name = dba_tab_privs.table_name (+) and dba_objects.object_type in ( 'PACKAGE', 'PROCEDURE', 'FUNCTION' ) and dba_objects.object_name like 'CTX_%' order by "Role needed to execute Package";
This results in the following output:
Package Role needed to execute Package --------------- ------------------------------ Ctx_Ddl CTXAPP Ctx_Output CTXAPP Ctx_Thes CTXAPP Ctx_Contains PUBLIC Ctx_Query PUBLIC Ctx_Doc PUBLIC Ctx_Adm
The following lists the CTX_DDL procedures used in this chapter, along with each procedure's arguments and descriptions.
procedure create_preference argument name type in/out default? ------------------------------ ----------------------- ------ -------- preference_name varchar2 in object_name varchar2 in procedure create_section_group argument name type in/out default? ------------------------------ ----------------------- ------ -------- group_name varchar2 in group_type varchar2 in procedure add_attr_section argument name type in/out default? ------------------------------ ----------------------- ------ -------- group_name varchar2 in section_name varchar2 in tag varchar2 in procedure add_field_section argument name type in/out default? ------------------------------ ----------------------- ------ -------- group_name varchar2 in section_name varchar2 in tag varchar2 in visible boolean in default procedure add_special_section argument name type in/out default? ------------------------------ ----------------------- ------ -------- group_name varchar2 in section_name varchar2 in procedure add_zone_section argument name type in/out default? ------------------------------ ----------------------- ------ -------- group_name varchar2 in section_name varchar2 in tag varchar2 in
In Oracle8i versions higher than 8.1.5, the XML section group offers the ability to index and search within attribute values. Consider a document with the following lines:
<comment author="jeeves"> I really like interMedia Text </comment>
Now XML section group offers an attribute section. This allows the inclusion of attribute values to index. For example:
ctx_ddl.add_attr_section('mysg','author','comment@author');
The syntax is similar to other add_section calls. The first argument is the name of the section group, the second is the name of the section, and the third is the tag, in the form <tag_name>@<attribute_name>. This tells interMedia Text to index the contents of the author attribute of the comment tag as the section "author".
Query syntax is just like for any other section:
WHERE CONTAINS ( ... ,'jeeves WITHIN author...',...)...
and finds the document.
Attribute sections allow you to search the contents of attributes. They do not allow you to use attribute values to specify sections to search. For instance, given the document:
<comment author="jeeves"> I really like interMedia Text </comment>
You can find this document by asking:
jeeves within comment@author
which is equivalent to "find me all documents which have a comment element whose author attribute's value includes the word jeeves".
However, there is no way to ask for something like:
interMedia within comment where (@author = "jeeves")
in other words, "find me all documents where interMedia appears in a comment element whose author is jeeves". This feature -- attribute value sensitive section searching -- is planned for future versions of the product.
Because the section group is defined before creating the index, 8.1.5 is limited in its ability to cope with changing structured document sets; if your documents start coming with new tags, or you start getting new doctypes, you have to re-create the index to start making use of those tags.
8.1.6 and higher allows you to add new sections to an existing index without rebuilding the index, using alter index and the new add section parameters string syntax:
add zone section <section_name> tag <tag> add field section <section_name> tag <tag> [ visible | invisible ]
For instance, to add a new zone section named tsec using the tag title:
alter index <indexname> rebuild parameters ('add zone section tsec tag title')
To add a new field section named asec using the tag author:
alter index <indexname> rebuild parameters ('add field section asec tag author')
This field section would be invisible by default, just like when using add_field_section. To add it as visible field section:
alter index <indexname> rebuild parameters ('add field section asec tag author visible')
Dynamic add section only modifies the index meta-data, and does not rebuild the index in any way. This means that these sections take effect for any document indexed after the operation, and do not affect any existing documents -- if the index already has documents with these sections, they must be manually marked for re-indexing (usually with an update of the indexed column to itself).
This operation does not support addition of special sections. Those would require all documents to be re-indexed, anyway. This operation cannot be done using rebuild online, but it should be a fairly quick operation.
Use AUTO_SECTION_GROUP group type to automatically create a zone section for each start-tag/end-tag pair in an XML document. The section names derived from XML tags are case-sensitive as in XML.
Attribute sections are created automatically for XML tags that have attributes. Attribute sections are named in the form attribute@tag.
Stop sections, empty tags, processing instructions, and comments are not indexed.
The following limitations apply to automatic section groups:
The following command creates a section group called auto with the AUTO_SECTION_GROUP group type. This section group automatically creates sections from tags in XML documents.
begin ctx_ddl_create_section_group('auto', 'AUTO_SECTION_GROUP'); end; create index myindex on docs(htmlfile) indextype is ctxsys.context parameters('filter ctxsys.null_filter section group auto');
|
 Copyright © 1996-2000, Oracle Corporation. All Rights Reserved. |
|