create materialized view log on aa;
create materialized view aa on prebuilt table with reduced precision refresh fast with primary key for update as select * from user.aa@dblink;
1.materialized view log
materialized view log只有在fast refresh的时候需要创建。fast refresh是利用materialized view log中的信息来实现增量改变。
2.on prebuilt table
3.with reduced precision
If the materialized view was registered as PREBUILT, the precision of the columns must agree with the precision of the corresponding SELECT expressions unless overridden by the WITH REDUCED PRECISION clause.
The contents of the table must reflect the materialization of the defining query at the time you register it as a materialized view, and each column in the defining query must correspond to a column in the table that has a matching datatype. However, you can specify WITH REDUCED PRECISION to allow the precision of columns in the defining query to be different from that of the table columns.
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