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Franck Pachot

Wrong result with multitenant, dba_contraints and current_schema

By | Oracle | No Comments

Multitenant architecture is not such a big change and this is why I recommend it when you start a project in 12c or if you upgrade to 12.2 – of course after thoroughly testing your application. However, there is a point where you may encounter problems on dictionary queries, because it is really a big change internally. The dictionary separation has several side effects. You should test carefully the queries you do on the dictionary…

 
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Franck Pachot

Active Data Guard services in Multitenant

By | Oracle | No Comments

A database (or the CDB in multitenant) registers its name as the default service. When a standby database is on the same server, or same cluster, you have no problem because this database name is the db_unique_name which is different between the primary and the standby(s). In multitenant, in addition to that, each PDB registers its name as a service. But the PDB name is the same in the primary and the standby database. This…

 
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Franck Pachot

12c dbms_stats.gather_table_stats on GTT do not commit

By | Oracle | No Comments

In my UKOUG OracleScene article on 12c online statistics and GTT I mentioned the following: A final note about those 12c changes in statistics gathering on GTT. In 11g the dbms_stats did a commit at the start. So if you did gather stats after the load, you had to set the GTT as ON COMMIT PRESERVE ROWS. Or you just vacuum what you’ve loaded. That has changed in 12c. If you now choose to do…

 
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Franck Pachot

When PDB name conflicts with CDB name

By | Business Intelligence, Oracle | No Comments

Going to multitenant architecture is not a big change. The administration things (DBA, monitoring, backups) connect to the CDB and the application things connect to the PDB. Without the multitenant option, it is still recommended to go to the CDB architecture. The non-CDB is deprecated and the multitenant architecture brings interesting features. People often ask how to name the CDB and the PDB, especially when they have naming rules or policies in the company. My…

 
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Franck Pachot

Bequeath connect to PDB: set container in logon trigger?

By | Database Administration & Monitoring, Oracle | No Comments

There are little changes when you go to multitenant architecture and one of them is that you must connect with a service name. You cannot connect directly to a PDB with a beaqueath (aka local) connection. This post is about a workaround you may have in mind: create a common user and set a logon trigger to ‘set container’. I do not recommend it and you should really connect with a service. Here is an…

 
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Franck Pachot

12cR2 Application Containers and Foreign Keys

By | Database management, Oracle | 2 Comments

Application Container brings a new way to share data among databases, and adds a new dimension to referential integrity. A foreign key in an application PDB can reference a row belonging to a root data link table. But then, should a delete on the root validate that there are no orpheans in the application PDBs? And what if those PDBs are closed at the time of this delete? Here is a small example.  

 
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