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Oracle 12c

Display Data Guard configuration in SQL Developer

The latest version of SQL Developer, the 17.2 one released after Q2 of 2017, has a new item in the DBA view showing the Data Guard configuration. This is the occasion to show how you can cascade the log shipping in Oracle 12c

A quick note about this new versioning: this is the release for 2017 Q2 and the version number has more digits to mention the exact build time. Here this version is labeled 17.2.0.188.1159 and we can see when it has been built:

SQL> select to_date('17.x.0.188.1159','rr."x.0".ddd.hh24mi') build_time from dual;
 
BUILD_TIME
--------------------
07-JUL-2017 11:59:00

PeopleSoft and Adaptive Query Optimization in Oracle 12c

Adaptive Query Optimization is a significant feature in Oracle 12c. Oracle has made lots of information available on the subject.(See https://blogs.oracle.com/optimizer/oracle-database-12c-is-here).

12c Multitenant Internals: VPD for V$ views

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 before the dictionary is opened or even created. Just start an instance in NOMOUNT and you can query the V$ views. Even in multitenant, you can switch to different containers in MOUNT, and query V$ views, when no dictionary is opened.

12cR2 Application Containers and Foreign Keys

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.

If you run this in 12.2.0.1 you will get an error because the search for parent key is done only on the current container. This is considered as a bug: 21955394: CDB:ORA-02291 WHEN FOREIGN KEY REFERS TO THE PRIMARY KEY IN DATA LINK

The example that follows is run with the patch applied to fix this bug.

12c NSSn process for Data Guard SYNC transport

In a previous post https://blog.dbi-services.com/dataguard-wait-events-have-changed-in-12c/ I mentioned the new processes NSA for ASYNC transport and NSS for SYNC transport. I’m answering a bit late to a comment about the number of processes: yes there is one NSSn process per LOG_ARCHIVE_DEST_n destination in SYNC and the numbers match.

Here is my configuration with two physical standby:
DGMGRL> show configuration
 
Configuration - orcl
 
Protection Mode: MaxPerformance
Members:
orcla - Primary database
orclb - Physical standby database
orclc - Physical standby database
 
Fast-Start Failover: DISABLED
 
Configuration Status:
SUCCESS (status updated 56 seconds ago)

12cR2 PDB refresh as a poor-man standby?

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 this usage, and are quite new and not stable yet. Disaster Recovery must use safe and proven technologies and this is why I’ll stick with Dbvisit standby for disaster recovery in Standard Edition.

This post explains what I had in my mind whith the following tweet:
CapturePoorManSBY

12cR2 auditing all users with a role granted

12.1 introduced Unified Auditing where you define policies and then enable them. As with the traditional audit, you enable them for all users or for specific users. The unified auditing adds a syntax to audit all users except some listed ones. 12.2 adds a syntax to audit a group of users, defined by the role granted. This is the best way to enable a policy for a group of users, including those created later.

I create a simple policy, to audit logon and DBA role usage:

SQL> create audit policy DEMO_POLICY actions logon, roles DBA;
Audit POLICY created.

I create a new DBA user, USER1

SQL> create user USER1 identified by covfefe quota unlimited on USERS;
User USER1 created.
SQL> grant DBA to USER1;
Grant succeeded.

I want to enable the policy for this user because I want to audit all DBAs

New release model for JUL17 (or Oracle 17.3): RU and RUR

Updated June 5th

When reading about new version numbering in SQL Developer, I took the risk to change the title and guess the future version number for Oracle Database: Oracle 17.3 for the July (Q3) of 2017. Of course, this is just a guess.

Updated June 10th

Confirming the previous guess, we start to see some bugs planned to be fixed in version 18.1 which is probably the January 2018 Release Update.
Capture18.1

Which privilege for CREATE PLUGGABLE DATABASE from DB LINK?

When cloning a PDB from a remote CDB you need to define a database link to be used in the CREATE PLUGGABLE DATABASE … FROM …@… command. The documentation is not completely clear about the privileges required on the source for the user defined in the database link, so here are the different possibilities.

Remote clone

Here is what the documentation says:CapturePDBPrivsClone

So you can connect to the CDB or to the PDB.

12cR2 needs to connect with password for Cross-PDB DML

In a previous post, I explained that Cross-PDB DML, executing an update/delete/insert with the CONTAINERS() clause, seems to be implemented with implicit database links. Connecting through a database link requires a password and this blog post is about an error you may encounter: ORA-01017: invalid username/password; logon denied