Create fast-refresh MV over dblink on table without PK?
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11-03-2021 - |
문제
I want to create a materialized view between a primary system (Oracle 18c) and an external system (Oracle 19c) via a dblink.
- The MV would refresh on a 30-second schedule (since on-commit is not possible over a dblink).
- The table in the external system does not have a primary key.
I'm a novice. Here's what I've tried:
--in the external system:
create materialized view log on external_system.workorder with rowid;
--in the primary system:
create materialized view primary_system.workorder_mv
build immediate
refresh fast
start with sysdate next sysdate + (30/(60*60*24))
as
select
cast(workorderid as number(38,0)) as objectid,
wonum,
status,
--other fields
longitudex,
latitudey
from
external_system.workorder@gistomax
When I try the above, I get a litany of errors, starting with one that says I need a primary key.
I found a page that suggests that it's possible to do a fast refresh over a dblink. But the example uses a primary key, not a rowid.
Rowid materialized views are not eligible for fast refresh after a master table reorganization until a complete refresh has been performed.
But I don't really know what that means. And to be honest, I'm so new at this, that I know I'm barking up the wrong tree, so I'll stop there.
Question:
Is it possible to create a fast-refresh MV over a dblink on table that doesn't have a PK?
해결책
As already demonstrated in your other question, a unique constraint on a NOT NULL
column is good enough to create an mview log with "PK" values. That can be used for fast refresh.
SQL> conn bp/bp
Connected.
SQL> create database link self connect to bp identified by bp
using 'localhost:1521/RYMIN19';
Database link created.
SQL> create table t1 (c1 number not null unique, c2 number);
Table created.
SQL> create materialized view log on t1 with primary key;
Materialized view log created.
SQL> create materialized view mv1 refresh fast on demand as select * from t1@self;
Materialized view created.
SQL> insert into t1 values (1, 1);
1 row created.
SQL> insert into t1 values (2, 2);
1 row created.
SQL> commit;
Commit complete.
Then:
SQL> exec dbms_mview.refresh('MV1', 'f');
PL/SQL procedure successfully completed.
SQL> select last_refresh_type from user_mviews where mview_name = 'MV1';
LAST_REF
--------
FAST