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.
Use the procedure CTX_DOC.GIST to generate gists and theme summaries. You can specify the size of the gist or theme summary when you call the procedure.
Oracle Text Reference to learn about the command syntax for CTX_DOC.GIST
The following example generates a nondefault 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 nondefault 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;