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Oracle Team

Oracle 12cR2: MAX_PDBS

By | Database Administration & Monitoring | 5 Comments

By Franck Pachot . Oracle database 12.2 is there on the Database Cloud Service, in multitenant. In EE High Performance or Extreme Performance, you have the multitenant option: you can create 4096 pluggable database (instead of 252 in 12.1). If you are in lower services, you can create only one user PDB (not counting application root and proxy PDB). If you are in Standard Edition, it’s simple: it is a hard limit. If you are…

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Oracle Team

12cR2 multitenant containers in SQL_TRACE

By | Database Administration & Monitoring | No Comments

By Franck Pachot . In multitenant you session can switch between containers. For example, since 12.1, a common user can switch explicitly between CDB$ROOT and any PDB with the ‘ALTER SYSTEM SET CONTAINER’. Any user connected to a PDB will also have it session switching implicitely when querying through metadata links and data links (new name for object links). In 12.1 there are no ways to trace this. This is fixed in 12.2

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Oracle Team

Oracle 12cR2 multitenant: Local UNDO

By | Database Administration & Monitoring | 10 Comments

By Franck Pachot . Pluggable Databases are supposed to be isolated, containing the whole of user data and metadata. This is the definition of dictionary separation coming with multitenant architecture: only system data and metadata are at CDB level. User data and metadata are in separate tablespaces belonging to the PDB. And this is what makes the unplug/plug available: because PDB tablespaces contain everything, you can transport their datafiles from one CDB to another. However,…

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Oracle Team

Oracle 12cR2 PL/SQL new feature: TNSPING from the database

By | Database Administration & Monitoring | No Comments

By Franck Pachot . Database links are resolved with the server TNS_ADMIN configuration (sqlnet.ora and tnsnames.ora). You can use tnsping to check the resolution, but it supposes that you are on the server and have set the same environment as the one which started the database. In 12.2 you have a new package to check that: DBMS_TNS. It’s the kind of little new features that make our life easier. The easy way to verify a…

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Oracle Team

Oracle 12cR2: IS_ROLLING_INVALID in V$SQL

By | Database Administration & Monitoring | No Comments

By Franck Pachot . In a previous post I published a test case to show when a cursor is not shared anymore after a rolling invalidation. Basically the dbms_stats marks the cursor as ‘rolling invalid’ and the next execution marks it as ‘rolling invalid executed’. Looking at 12cR2 there is a little enhancement in V$SQL with an additional column displays those states.

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Oracle Team

Oracle 12cR2 Optimizer Adaptive Statistics

By | Database Administration & Monitoring | 9 Comments

By Franck Pachot . When 12.1 came out, the major issue we encountered after migration was related to the new adaptive features of the optimizer: automatic reoptimization, SQL Plan Directives and the resulting dynamic sampling. Of course, Oracle product managers listen to feedbacks, ensure to provide workarounds or fixes and make things better for next release. Let’s see what has been announced on this topic for 12.2

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