Oracle Text performance -- failed attempts

Question

We are trying to implement a simple search of text data stored in a heavily used table (inserts/updates). There are 3 columns to index --
Headline (varchar2(255))
Subheadline (varchar2(255))
Teaser (varchar2(4000))
The first attempt to implement Oracle text w/ CATSEARCH
begin
ctx_ddl.create_index_set('cms_iset');
ctx_ddl.add_index('cms_iset','poolid_cp, mediaid_cp'); /* sub-index A */
end;
---- We knew we were going to filter on poolid_cp and mediaid_cp ---
CREATE INDEX cms_headlineidx ON con_properties (headline)
INDEXTYPE IS ctxsys.CTXCAT
PARAMETERS ('index set cms_iset');
CREATE INDEX cms_subheadlineidx ON con_properties (subheadline)
INDEXTYPE IS ctxsys.CTXCAT
PARAMETERS ('index set cms_iset');
CREATE INDEX cms_teaseridx ON con_properties (teaser)
INDEXTYPE IS ctxsys.CTXCAT
PARAMETERS ('index set cms_iset');
*********THE RESULTS*************
Our application server would spin up threads that would appear to be hanging. The load on the DB servers (RAC) were higher than normal. This implementation would have saved on having to do resync's manually.
The next attempt was implementing w/ CONTEXT:
alter table con_properties add (dummy varchar2(1));
begin
ctx_ddl.create_preference('con_propsearch', 'MULTI_COLUMN_DATASTORE');
ctx_ddl.set_attribute('con_propsearch', 'columns', 'headline,subheadline,teaser');
end;
CREATE INDEX con_properties_searchidx
ON con_properties(dummy)
INDEXTYPE IS CTXSYS.CONTEXT
PARAMETERS ('datastore CTXSYS.con_propsearch')
Records getting put into the ctx_user_pending table a few hundred per hour.
********THE RESULTS*************
Same issue with the application servers spinning off threads that seem to be hung. Spikey load on the DB servers (RAC).
NOTE: In both implementations, running search querys ran OK. However, dropping the text index in BOTH cases caused the application servers to behave normally.
Can anyone tell me what's going on internally with Oracle TEXT when a table is heavily inserted and updated? What is going on in the background. Is there some sort of lock that the app servers are waiting on? I know there is "overhead" with inserts on a normal b-tree index. Is it "exponential" with Oracle Text?
Thank you!

Answer 1

When documents in the base table are inserted, updated, or deleted, their ROWIDs are held in a DML queue until you synchronize the index. You can view this queue with the CTX_USER_PENDING view. Apparently, you are not synchronizing your context index, so the queue is building infinitely. You need to establish some method of synchronizing your index. You can use parameters('sync(on commit)') in your index creation or create an after insert or update statement level trigger, not row trigger, that uses dbms_job.submit to schedule ctx_ddl.sync_index to synchronize the index upon commit of the dml or you can manually run ctx_ddl.sync_index periodically or schedule it or you can alter and rebuild your index periodically or you can drop and recreate it periodically. Which method you choose depends on how current the information that you query needs to be. If your data needs to be current up to the moment, the you should sync on commit. Otherwise it may be better to do it in periodic batches.