|Oracle® Text Application Developer's Guide
10g Release 1 (10.1)
Part Number B10729-01
This chapter describes document presentation. The following topics are covered:
In Oracle Text query applications, you can present selected documents with query terms highlighted for text queries or with themes highlighted for ABOUT queries.
You can generate three types of output associated with highlighting: a marked-up version of the document, a plain text version of the document (filtered output), and highlight offset information for the document.
The three types of output are generated by three different procedures in the
CTX_DOC (document services) PL/SQL package. In addition, you can obtain plain text and HTML versions for each type of output.
For text highlighting, you supply the query, and Oracle Text highlights words in document that satisfy the query. You can obtain plain-text or HTML highlighting.
ABOUT queries, the
CTX_DOC procedures highlight and mark up words or phrases that best represent the
There are three highlighting procedures in
Highlight offset information is useful for when you write your own custom routines for displaying documents.
To obtain highlight offset information, use the
CTX_DOC.HIGHLIGHT procedure. This procedure takes a query and a document, and returns highlight offset information for either plaintext or HTML formats.
With offset information, you can display a highlighted version of document as desired. For example, you can display the document with different font types or colors rather than using the standard plain text markup obtained from
See Also:Oracle Text Reference for more information about using
You can customize the markup sequence for HTML navigation.
The following example is taken from the Web application described in Appendix A, " CONTEXT Query Application". The procedure
showDoc takes an HTML document and a query, creates the highlight markup, and outputs the result to an in-memory buffer. It then uses htp.print to display it in the browser.
procedure showDoc (p_id in varchar2, p_query in varchar2) is v_clob_selected CLOB; v_read_amount integer; v_read_offset integer; v_buffer varchar2(32767); v_query varchar(2000); v_cursor integer; begin htp.p('<html><title>HTML version with highlighted terms</title>'); htp.p('<body bgcolor="#ffffff">'); htp.p('<b>HTML version with highlighted terms</b>'); begin ctx_doc.markup (index_name => 'idx_search_table', textkey => p_id, text_query => p_query, restab => v_clob_selected, query_id => 0, starttag => '<i><font color=red>', endtag => '</font></i>'); v_read_amount := 32767; v_read_offset := 1; begin loop dbms_lob.read(v_clob_selected,v_read_amount,v_read_offset,v_buffer); htp.print(v_buffer); v_read_offset := v_read_offset + v_read_amount; v_read_amount := 32767; end loop; exception when no_data_found then null; end; exception when others then null; --showHTMLdoc(p_id); end; end showDoc; end; / show errors set define on
See Also:Oracle Text Reference for more information about
See Also:Oracle Text Reference for more information about
This procedure takes a binary document as BLOB and uses the Inso filter to output text to a CLOB. This procedure is useful with MATCHES query, which can use CLOB data as input. The procedure can also be called from a user datastore procedure as a binary to text filter.
The following table describes lists of themes, gists, and theme summaries.
Table 5-1 Lists of Themes, Gists, and Theme Summaries
|List of Themes||A list of the main concepts of a document.
You can generate list of themes where each theme is a single word or phrase or where each theme is a hierarchical list of parent themes.
|Gist||Text in a document that best represents what the document is about as a whole.|
|Theme Summary||Text in a document that best represents a given theme in the document.|
To obtain this output, you use procedures in the
CTX_DOC supplied package. With this package, you can do the following:
Identify documents by
ROWID in addition to primary key
Store results in-memory for improved performance
See Also:Oracle Text Reference to learn more about the command syntax for
The following example generates the top 10 themes for document 1 and stores them in an in-memory table called
the_themes. The example then loops through the table to display the document themes.
declare the_themes ctx_doc.theme_tab; begin ctx_doc.themes('myindex','1',the_themes, numthemes=>10); for i in 1..the_themes.count loop dbms_output.put_line(the_themes(i).theme||':'||the_themes(i).weight); end loop; end;
To create a theme table:
create table ctx_themes (query_id number, theme varchar2(2000), weight number);
begin ctx_doc.themes('newsindex','34','CTX_THEMES',1,full_themes => FALSE); end;
A gist is the text of a document that best represents what the document is about as a whole. A theme summary is the text of a document that best represents a single theme in the document.
See Also:Oracle Text Reference to learn about the command syntax for
The following example generates a non-default size generic gist of at most 10 paragraphs. The result is stored in memory in a
CLOB locator. The code then de-allocates the returned
CLOB locator after using it.
declare gklob clob; amt number := 40; line varchar2(80); begin ctx_doc.gist('newsindex','34','gklob',1,glevel => 'P',pov => 'GENERIC', numParagraphs => 10); -- gklob is NULL when passed-in, so ctx-doc.gist will allocate a temporary -- CLOB for us and place the results there. dbms_lob.read(gklob, amt, 1, line); dbms_output.put_line('FIRST 40 CHARS ARE:'||line); -- have to de-allocate the temp lob dbms_lob.freetemporary(gklob); end;
To create a gist table:
create table ctx_gist (query_id number, pov varchar2(80), gist CLOB);
The following example returns a default sized paragraph level gist for document 34:
begin ctx_doc.gist('newsindex','34','CTX_GIST',1,'PARAGRAPH', pov =>'GENERIC'); end;
The following example generates a non-default size gist of ten paragraphs:
begin ctx_doc.gist('newsindex','34','CTX_GIST',1,'PARAGRAPH', pov =>'GENERIC', numParagraphs => 10); end;
The following example generates a gist whose number of paragraphs is ten percent of the total paragraphs in document:
begin ctx_doc.gist('newsindex','34','CTX_GIST',1, 'PARAGRAPH', pov =>'GENERIC', maxPercent => 10); end;
Typically, a query application enables the user to view the documents returned by a query. The user selects a document from the hit list and then the application presents the document in some form.
With Oracle Text, you can display a document in different ways. For example, you can present documents with query terms highlighted. Highlighted query terms can be either the words of a word query or the themes of an
ABOUT query in English.
You can also obtain gist (document summary) and theme information from documents with the
CTX_DOC PL/SQL package.
Table 5-2 describes the different output you can obtain and which procedure to use to obtain each type.
Table 5-2 CTX_DOC Output
|Plain text version, no highlights||CTX_DOC.FILTER|
|HTML version of document, no highlights||CTX_DOC.FILTER|
|Highlighted document, plain text version||CTX_DOC.MARKUP|
|Highlighted document, HTML version||CTX_DOC.MARKUP|
|Highlight offset information for plain text version||CTX_DOC.HIGHLIGHT|
|Highlight offset information for HTML version||CTX_DOC.HIGHLIGHT|
|Theme summaries and gist of document.||CTX_DOC.GIST|
|List of themes in document.||CTX_DOC.THEMES|
See Also:The Oracle Text Reference
Figure 5-1 shows an original document to which we can apply highlighting, gisting, and theme extraction in the following sections.
Figure 5-2 is a screen shot of a query application presenting the document shown in Figure 5-1 with the query term pet highlighted. This output was created using the text query application produced by a wizard described in Appendix A, " CONTEXT Query Application".
Figure 5-3 is a screen shot of a query application presenting a list of themes for the document shown in Figure 5-1. This output was created using the text query application produced by a wizard described in Appendix A, " CONTEXT Query Application".
Figure 5-4 is a screen shot of a query application presenting a gist of the document shown in Figure 5-1. This output was created using the text query application produced by a wizard described in Appendix A, " CONTEXT Query Application".