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Franck Pachot

Multitenant vs. schema based consolidation

By | Database management, Oracle | 4 Comments

If you want to install multiple instances of a software, for example you host the ERP for several companies or subsidiaries, you have 3 solutions: have one database and multiple schema have multiple databases have one database and multiple pluggable databases Of course, this is exactly the reason for pluggable databases: multitenant. You have good isolation but still share resources. A lot of reasons have been given why multiple schema – or schema based consolidation…

 
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Franck Pachot

12c: shutdown abort a PDB?

By | Database management, Oracle | 3 Comments

Can we shutdown abort a PDB? Let’s try: SQL> show con_id CON_ID —————————— 3SQL> shutdown abort; Pluggable Database closed. But is it really a shutdown abort? The shutdown abort we know in non-CDB – or in a CDB from CDB$ROOT – is used when the instance cannot checkpoint before closing the file. It leaves the files fuzzy. And shutdown abort crashes the instance – loosing all changes made in buffer cache and not yet checkpointed….

 
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Franck Pachot

Oracle multitenant dictionary: rowcache

By | Database management, Oracle | No Comments

I’ve not finished with my investigation on 12c multitenant dictionary. Here, I’m checking how metadata links are managed by the dictionary cache (aka rowcache). As I did previously, I’ll create a metadata link function in my lab environment (this is not for production. For the moment metadata/object links are supported only for oracle objects). SQL> connect / as sysdba Connected. SQL> create or replace function DEMO_MDL_FUNCTION sharing=metadata 2 return varchar2 as 3 begin return ‘XXXXXXXXXX';…

 
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Franck Pachot

Stay with non-CDB or go to CDB?

By | Database management, Oracle | 5 Comments

This is a question that starts to be raised quite frequently. Oracle released the multitenant architecture 1.5 year ago. And now says that the previous architecture – known as non-CDB – is deprecated. What does it mean? Do we have to go to the CDB architecture even if we don’t want to use/pay multi-tenant? It started like that on twitter: Non-CDB architecture of Oracle databases is DEPRECATED since Oracle Database 12.1.0.2 https://t.co/7mDO93lGee via Mike Dietrich…

 
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Franck Pachot

Oracle 12c: comparing TTS with noncdb_to_pdb

By | Database management, Oracle | No Comments

How to migrate from non-CDB to CDB? Of course all known migration methods works. But there is also another solution: upgrade to 12c if necessary and then convert the non-CDB to a PDB. This is done with the noncdb_to_pdb.sql which converts a non-CDB dictionary to a PDB one, with metadata and object links. But do you get a clean PDB after that ? I tested it and compared the result with same database migrated by…

 
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Franck Pachot

When Oracle resets session statistics

By | Database management, Oracle | No Comments

During our Oracle 12c New Features workshop I had a very good question about whether the session statistics are reset or not when doing ALTER SESSION SET CONTAINER. My initial thought was that they were not reset because it’s the same session (same SID and SERIAL#). But when I’m not 100% sure about something, I test it. And once again, it proves that even the instructor can learn something new when giving a workshop, thanks…

 
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Franck Pachot

12.1.0.2 CDB views are now using CONTAINERS()

By | Database management, Oracle | 2 Comments

I’ve blogged about multitenant internals at the time when 12.1.0.1 was just released. Something has changed in 12.1.0.2 and blogging about it was in my todo list for a long time. Now the occasion to do it has been triggered by a question on Oracle Forums about CDB_DATA_FILES not showing PDB$SEED datafiles because there is an important change we must be aware of. In the previous blog, I have described how you can query PDB…

 
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Franck Pachot

Oracle 12c CDB – metadata & object links internals

By | Database management, Oracle | 21 Comments

Warning: this is only geek stuff about internals on multitenant database dictionary, metadata, and object links. It has nothing to do with the operations that you can do on your database. Don’t try that in production or you can corrupt the whole dictionary. In 12 multitenant database (aka CDB) we know that each pluggable database is isolated in order to act as a standalone database. But they share some common resources because that’s the main…

 
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Olivier Toussaint

Oracle Database 12c : démarrage automatique des Pluggable Databases

By | Database management | No Comments

Dans ce blog post, nous allons nous intéresser à la gestion des PDBs (Pluggable Database) dans Oracle 12c. Plus exactement, nous allons nous pencher sur l’arrêt et le démarrage automatiques des PDBs en utilisant le Server Control (srvctl) du Grid Infrastructure de la 12c. Le contexte Au préalable, il faut avoir installé Grid Infrastructure et créé une CDB (Container Database) avec une PDB. Nous allons utiliser le processus d’Oracle Restart pour gérer l’arrêt et le…

 
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Yann Neuhaus

Oracle Database 12c: PDBs not fully transportable yet

By | Database management | No Comments

One of the benefits of the new Oracle multi-tenant database option is to create a kind of cloned environment through simple statements. This post will focus on the creation of pluggable database through a database link. The reason of this topic is that I am currently developing an advanced RMAN cloning procedure for 11g and this new 12c feature might make our life much easier in the future release. The second reason of choosing this…

 
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