Skipping changes in Streams

Question

We're using CDC (built on Streams from what I can tell) to replicate changes from OLTP system to a data warehouse. There is a need to correct a value in a column as a mass update which will affect many rows, but we don't want to send those changes to the warehouse. So what we're stuck on is how to prevent CDC capturing those changes or make it skip them.
We're thinking we would issue dbms_capture_adm.stop_capture, perform the update, then issue dbms_capture_adm.start_capture, but that doesn't work as it just seems to 'pause' the capture and when it restarts, ALL the changes are mined from the redo logs.
I'm guessing what we need to do is before we restart the capture, we need to issue dbms_capture_adm.alter_capture to manipulate the SCNs, is that correct, and if so which SCN and what to set it to?
I think all the dbms_capture_adm apis effectively calls the streams equivalent, if anybody has manage to "skip" changes with streams or cdc, then please post.
eg,.
exec dbms_capture_adm.stop_capture('test_capture');
update big table...*
exec dbms_capture.alter_capture(???);
exec dbms_capture_adm.start_capture('test_capture');

Answer 1

One way that i have tested to skip changes is to use apply_tag.
First your capture rule need to have :dml.is_null_tag() = 'Y' so that only changes without apply tag are captured.
Second in the session performing the mass update you need to set a tag. This can be achieved through DBMS_STREAMS.SET_TAG procedure.
As far that I understand the streams, this does not imply to verify the stream is empty.But you must be aware that according to CDC configuration (I have never practised CDC) this may lead to apply errors.
Here is my capture process positive rule:
(CLOB) ((((:dml.get_object_owner() = 'SAG') and *:dml.is_null_tag() = 'Y'* and :dml.get_source_database_name() = 'ORCLUDR01.FR.NETCENTREX.NET' )) and (:dml.get_compatible() <= dbms_streams.compatible_11_1))
Here is a sample sqlplus session:
Show that stream works
SQL> connect sag/sag
SQL> select * from test;
ID LIB
11 1
12 2
10 0
SQL> update test set LIB='00' where id=10;
1 row updated.
SQL> commit;
Commit complete.
SQL> connect strmadmin/strmadmin
SQL> select * from sag.test@orcludr02
ID LIB
10 00
11 1
12 2
connect sag/sag
Place tag
SQL> begin
2 DBMS_STREAMS.SET_TAG(hextoraw('0000'));
3* end;
PL/SQL procedure successfully completed.
Update not replicated
SQL>update test set lib='0000' where id=10;
1 row updated.
SQL> commit;
Commit complete.
Verify update worked and was not captured
SQL> connect strmadmin/strmadmin
Connected.
SQL> select * from sag.test;
ID LIB
11 1
12 2
10 0000
SQL> select * from sag.test@orcludr02;
ID LIB
10 00
11 1
12 2