By Franck Pachot . When I explain the multitenant internals, I show that all metadata about system procedures and packages are stored only in CDB$ROOT and are accessed from the PDBs through metadata links. I take an example with DBMS_SYSTEM that has nothing in SOURCE$ of the PDB. But I show that we can compile it from the PDB. This…
By Franck Pachot . This month, I’ll talk – with lot of demos – about multitenant internals at DOAG conference. The multitenant dictionary architecture starts with a simple idea: system metadata and data are in CDB$ROOT and user metadata and data are in PDB. And it could have been that simple. When a session connected to a PDB needs to…
By Franck Pachot . The documentation says that for Reduction of duplication and Ease of database upgrade the Oracle-supplied objects such as data dictionary table definitions and PL/SQL packages are represented only in the root. Unfortunately, this is only partly true. System PL/SQL packages are only in root but system table definition are replicated into all PDBs. This post is…
By Franck Pachot . The development teams often see the database as a ‘persistence layer’ only. And sometimes it is mentioned that the database is always the cause of the problems, especially when implementing continuous integration and trying to be agile. Then cames the idea to have this ‘persistence layer’ in an isolated environment, such as a docker container, with…
By Franck Pachot . Larry Ellison has announced Oracle 18c to be the Autonomous Database, the no-human labor, and self-driven, database. Here is a quick recap of what it is behind the marketing words. My opinion only. Autonomous Since Oracle decided to be a public cloud PaaS provider, they announced ‘unmanaged’ and ‘managed’ services. The managed service for DBaaS is…
By Franck Pachot . There are currently a lot of new buzz words and re-namings which suggest that our DBA role is changing, most of them escorted with a #cloud hashtag. Oracle Technology Network is now called Oracle Developer Community. Larry Ellison announced the database that does not need to be operated by humans. And people talking about the death…
By Franck Pachot . 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…
By Franck Pachot . 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…
By Franck Pachot . 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…
By Franck Pachot . 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…
By Franck Pachot . I described in an earlier post on AWR views how the dictionary views were using metadata and object links to show information from other containers. But this mechanism cannot work for fixed views (aka V$) because they don’t have their definition in the dictionary. The big difference is that most of V$ views are available long…
By Franck Pachot . Disclaimer My goal here is only to show that the Refreshable PDB feature works by shipping and applying redo, and then can synchronize a copy of the datafiles. I do not recommend to use it for disaster recovery in any production environment yet. Even if I’m using only supported features, those features were not designed for…
