Big Doubt on SnapShot Refresh

[ligang]

Env.

Master DB : Oracle8.1.6
Slave DB : Oracle8.1.6



I created snapshot log based on Master DB --> scott.emp
CREATE SNAPSHOT LOG ON "SCOTT"."EMP" TABLESPACE "USERS"

Then I create a readonly snapshot on Slave DB and set to
use force refresh and refresh every hour -->

CREATE SNAPSHOT HR_EMP AS SELECT * FROM emp@HR;
ALTER SNAPSHOT HR_EMP REFRESH
START WITH to_date('19-May-2003 12:00:00 PM','dd-Mon-yyyy HH:MI:SS AM') NEXT sysdate + 1/24

But after everything is set up , To my surprise , Whenever I change
the EMP table in Master DB , The Data is instantly synchonized in
slave ( not in a hour based ) .

Later on , I change the refresh type to fast , then it works fine .
According to the definition of force refresh , it will first try to
use fast fresh , if failed , it will turn to use complete refresh !

Another question is on the snapshot log , actually I was considering the necessity to use snapshot log as in the real situation , the table to be snapshoted is huge , Will it be very costly if the snapshot log is created by that table .

[akhadar]

I don't think that u have any problem in that only thing u have to take care is amount of data that will be transferred as this is make your network busy.

[ligang]

Thanks .

Sorry to state that what I describle in the previous thread is a bit wrong . After change the add the snapshot log , actually the shapshot stops refresh and when I try to refresh it manually , it reports
error

ORA-12034 snapshot log on scott.emp younger than last refresh
then I have to use the complete refresh ... why

[akhadar]

check the following link

http://servo.oit.gatech.edu/docs/ora...5/repadden.htm

[akhadar]

Also see this link

http://www.experts-exchange.com/Data..._11258974.html

[ligang]

I solve the problem ,

create snapshot log first
then create snapshot