Re: context index size

Thank Tim, do you know any way to measure index related performance?

Honglin

In article <20001224083314.11937.00000856_at_ng-mo1.aol.com>,   timkarnold_at_aol.com (TimKArnold) wrote:
> If you take all the defaults, that includes thematic reduction which
 takes up a
> lot more space. Unless, you need it, I might turn that feature off.
> I believe the rule of thumb to start is 3X the text size that you
 are
> indexing. Over time that edges toward 1-1.
>
> Merry XMAS
>
> Tim
> Lanham, MD
>
> >Merry Christmas!
> >
> >Here I am using Oracle 8.1.6 on NT. I have a table to store XML
> >documents, which has the the following columns:
> >
> >VALUE: XML data; (CLOB)
> >PATH: path expression; (VARCHAR2)
> >RPATH: reverse path expression; (VARCHAR2)
> >
> >Then, I create a context index, set the preference of user_datastore,
> >which has a stored procedure to create index on mulitple columns:
 PATH,
> >VALUE, and RPATH on the fly.
> >
> >The table has about 30,000 rows (very small XML data, 1k size). When
> >the index is built, I found that 550MB was used by observing the disk
> >usage from NT. However, if I simply create context index on the
 column
> >VALUE, it would consume less than 10MB. or are there any tools to
> >measure the index?
> >
> >Can anyone explain for me? Attached please find the procedure. Thank
> >you!
> >
> >Honglin
> >
> >PS:
> >
> >create or replace procedure myproc
> >(rid in rowid, tlob in out clob)
> >is offset number:=1;
> >v_value clob;
> >v_path varchar2(128);
> >v_rpath varchar2(128);
> >
> >begin
> > if dbms_lob.istemporary(tlob) <> 1 then
> > raise_application_error (-20000,
> > '"IN OUT" tlob is not temporary');
> > end if;
> >
> > select path, value, rpath into
> > v_path, v_value, v_rpath
> > from xmldocuments where rowid=rid;
> >
> > dbms_lob.trim (
> > lob_loc => tlob,
> > newlen => 0
> > );
> >
> > dbms_lob.write (
> > lob_loc => tlob,
> > amount => length(v_path),
> > offset => 1,
> > buffer => v_path
> > );
> >
> > if not (v_value is null or
> > dbms_lob.getlength(v_value)<1)
> > then
> > dbms_lob.copy (
> > dest_lob => tlob,
> > src_lob => v_value,
> > amount => dbms_lob.getlength(v_value),
> > dest_offset => length(v_path) + 2,
> > src_offset => 1
> > );
> > end if;
> >
> > dbms_lob.write (
> > lob_loc => tlob,
> > amount => length(v_rpath),
> > offset => dbms_lob.getlength(tlob) + 2,
> > buffer => v_rpath
> > );
> >end myproc;
> >
> >
> >Sent via Deja.com
> >http://www.deja.com/
>
>

Sent via Deja.com
http://www.deja.com/ Received on Sun Dec 24 2000 - 22:11:41 CST