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Oracle 8 Tips
by Burleson Consulting |
The Data Warehouse Development Life Cycle
Distributed Oracle Data Warehouses
HOW ORACLE SNAPSHOTS WORK
Here, you can see that MY_REPLICATED_TABLE is refreshed each morning
at 3:00 AM, and the read-only name SNAP$_MY_REPLICATED_TABLE has
been replaced with the synonym MY_REPLICATED_TABLE. Following is an
example of the snapshot log syntax that needs to be run on the
master database:
CREATE SNAPSHOT LOG ON
customer_table
TABLESPACE ts2
STORAGE (initial 20k next 20k);
The dbms_snapshot.refresh_all procedure can be run at any time on
the DESTINATION data warehouse to refresh the snapshot tables. To
force a refresh of an individual table, execute the following:
EXECUTE
dbms_snapshot.refresh('office','f');
Note: Any refresh errors are written to the alert.log file.
The snapshot log is a table that resides in the same database as the
master table, which can be seen in the Remote DBA_tables view as a table
with the name MLOG$_tablename. In our example, the snapshot log
would be called MLOG$_CUSTOMER.
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