Oracle 11g Change Data Capture and CSCN$

Question

Hi Everyone,
I'm running Synchronous CDC in an all Oracle 11g environment. Looking in the PUBLISHER tables, I noticed something odd regarding the Oracle generated CSCN$ and COMMIT_TIMESTAMP$ columns. For some of the records, these values are set to:
CSCN$,                  COMMIT_TIMESTAMP$
281474976710655    01-JAN-00 00:00:00
281474976710655    01-JAN-00 00:00:00
These values never get picked up by the SUBSCRIBER, as the VIEW has a predicate to capture changes within a range far less than the above, ie:
CSCN$,             
COMMIT_TIMESTAMP$
10424608850601    03-JAN-14 10:54:05
10424608850601    03-JAN-14 10:54:05
So I'm wondering, why is Oracle insert those odd CSCN$ and TIMESTAMP values? Is it possibly records that have been UPDATED from source but the original INSERT of the record wasn't picked up by CDC. I'm not sure how CDC deals with UPDATES after the records have been INSERTED on the source but before CDC was 'turned on'?
Thanks for any help!
-Steve

Answer 1

Hi,
you can use dbms_streams.set_tag to hide transactions from replication.
see: http://docs.oracle.com/cd/E11882_01/server.112/e10705/rep_tags.htm#STREP390
sample:
BEGIN
DBMS_STREAMS.SET_TAG( tag => HEXTORAW('1D'));
delete from my_table where column1 = 1;
commit;
DBMS_STREAMS.SET_TAG( tag => null);
END;
the apply tag has to be another than is set to your apply process.
therefore first determine the actual tag for your session:
SET SERVEROUTPUT ON
DECLARE
raw_tag RAW(2048);
BEGIN
raw_tag := DBMS_STREAMS.GET_TAG();
DBMS_OUTPUT.PUT_LINE('Tag Value = ' || RAWTOHEX(raw_tag));
END;
first try with a sample...
kind regards
johann.