MV Refresh differences between 9i and 10g

Question

In 9i, the MV seems to be empty during complete refresh (Oracle does a truncate on the MV). I have done some tests on 10g and that does not occur (it seems that Oracle does a Delete). Does any one know this for sure?
Thanks

Answer 1

In 10g:
- A MV called MVTeste;
- Two SQL Plus windows: in both a make a 'select count' in the MV. Then, in the first one I do a dbms_mview.refresh. In the second one, I keep doing 'select count' in the MV. The second SQL Plus never sees an empty MV.
FIRST SQL PLUS
SQL*Plus: Release 9.2.0.1.0 - Production on Sab Mar 4 10:19:43 2006
Copyright (c) 1982, 2002, Oracle Corporation. All rights reserved.
Conectado a:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Production
With the Partitioning, OLAP and Data Mining options
SQL> set time on
10:19:55 SQL> set timing on
10:20:06 SQL> select count(*) from mvteste;
COUNT(*)
100000
Decorrido: 00:00:00.02
10:20:17 SQL> exec dbms_mview.refresh('MVTESTE');
Procedimento PL/SQL concluído com sucesso.
Decorrido: 00:00:39.09
10:21:20 SQL>
SECOND SQL PLUS
SQL*Plus: Release 9.2.0.1.0 - Production on Sab Mar 4 10:19:5
Copyright (c) 1982, 2002, Oracle Corporation. All rights res
Conectado a:
Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - P
With the Partitioning, OLAP and Data Mining options
SQL> set time on
10:20:02 SQL> set timing on
10:20:10 SQL> select count(*) from mvteste;
COUNT(*)
100000
Decorrido: 00:00:00.01
10:20:23 SQL> /
COUNT(*)
100000
Decorrido: 00:00:00.04
10:20:42 SQL> /
COUNT(*)
100000
Decorrido: 00:00:00.08
10:20:45 SQL> /
COUNT(*)
100000
Decorrido: 00:00:00.08
10:20:46 SQL> /
COUNT(*)
100000
Decorrido: 00:00:00.09
10:20:48 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:20:52 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.01
10:20:55 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:20:58 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:01 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:04 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:06 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:09 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:11 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:13 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:15 SQL> /
COUNT(*)
100000
Decorrido: 00:00:01.00
10:21:17 SQL> /
COUNT(*)
100000
Decorrido: 00:00:00.06
10:21:20 SQL> /
COUNT(*)
100000
Decorrido: 00:00:00.03
10:21:23 SQL>