If Performance Objectives are not being met, Quality of Service Management makes a recommendation. Each recommendation focuses on improving the highest-ranked Performance Class by exceeding its Performance Objective. Submissions may include changing consumer group mappings – and reprioritizing work within existing resource boundaries. For example, changing consumer group mappings may involve promoting a specific workload to get a more significant share of resources, or demoting a competing workload to make additional resources available to the target Performance Class. Another recommendation is to move servers between server pools and reprioritize resources between them to meet workload demands; so effectively, taking a node out of one pool and adding it to another pool gives more resources to the Performance Class running in that pool. And another recommendation is moving CPUs between databases within a server pool – reprioritize CPU resources within existing server pool boundaries. And this is called instance caging, where the CPU count parameter is set to limit the amount of CPUs an instance can use on a node.

The Quality of Service Management recommendations to improve the performance of a particular Performance Class adds more of the bottleneck resource – such as CPU time – for that Performance Class, making the bottleneck resource available more quickly to work requests in the Performance Class. Adding more resources to a Performance Class that is not performing well means taking resources away from another Performance Class. The Performance Class where the resources are removed should be less business-critical than the one being helped. So overall, the reallocation of resources should be beneficial to the business. When generating recommendations, Quality of Service Management evaluates the impact of the system performance as a whole. For example, suppose the improvement for one Performance Class is rather tiny, but the adverse effects on another Performance Class are significant. In that case, Quality of Service Management might report that the performance gain is too small and not recommended. If there is more than one way to resolve the bottleneck, Quality of Service Management advises the best overall recommendation. It is invariable, such as the calculated impact on all the Performance Classes and the predicted disruption and settling time associated with the action. And using Oracle Enterprise Manager, you can view the current and the alternative recommendations. Performance data is sent to Oracle Enterprise Manager for display on the Quality of Service Management Dashboard and Performance History pages. By default, Oracle Database QoS Management does not automatically implement recommendations. Instead, it suggests improving performance, which the administrator must then implement by clicking the Implement button. From version, Quality of Service Management allows you to specify authorized automatic actions that it can implement without the intervention of an administrator.

When patching an Oracle home, you might run into problems. OPatch might not behave as expected. It is helpful to know where to look for error messages or find additional information to pass on to Oracle Support if you want to log an SR for your problem. So OPatch maintains logs for apply, rollback, and lsinventory operations. The OPatch log files are located in the $ORACLE_HOME/cfgtoollogs/opatch. Each time you run OPatch, a new log file is created, and each log file is tagged with the operation’s timestamp. OPatch maintains an index of processed commands and log files in the opatch_history.txt file – and that is also in the above-mentioned $ORACLE_HOME/cfgtoollogs/opatch directory. So if you change the directory to $ORACLE_HOME/cfgtoollogs/opatch, you’ll see that every time you run OPatch, a log file is created with a date stamp. And then, at the bottom, you’ll see an opatch_history.txt file. look at the file, you’ll see a record of each time you ran the opatch apply, opatch rollback, or lsinventory command. The DBMS_QOPATCH package provides a PL/SQL or a SQL interface to view the installed database patches.

The package returns the patch and patch metadata information available as part of the “opatch lsinventory -xml” command in real-time. So it’s basically a way to see which patches are applied to your database home but from a PL/SQL or a SQL interface. So you basically get an XML-formatted return of your patch information. The DBMS_QOPATCH package allows users to query what patches are installed from SQL*Plus, write wrapper programs to create reports and do validation checks across multiple environments, and also to check patches installed on cluster nodes from a single location. If you log into SQL*Plus as the sys user and then perform select DBMS_QOPATCH.GET_OPATCH_LSINVENTORY from dual. And you’ll see just lots of XML information – which you can use an XML parser to make sense of it.

Starting in Oracle Database 12c, the multithreaded Oracle model enables specific Oracle processes to execute as operating system threads in separate address spaces. Setting up an Oracle database instance for using multi-process multi-thread architecture is done by starting up the Oracle database instance with the THREADED_EXECUTION initialization parameter set to TRUE.

The multi-process multi-thread model requires a password file for SYSDBA authentication while starting the database instance. Without using the SYS password

an  ORA-1031: insufficient privileges error will be triggered on startup.

When the THREADED_EXECUTION parameter is set to TRUE, you must set the DEDICATED_THROUGH_BROKER_LISTENER parameter to ON in your listener.ora file.

When that parameter is set, the listener knows that it should not spawn an OS process when a connect request is received; instead, it passes the request to the database so that a database thread is spawned and answers the connection.




There have been a few issues related to the grid inter-process communication(GIPC) daemon. Since this lets redundant interconnect usage, it would produce many networks interconnect messages. Previously, I carried out a cyclic cleanup of the ‘gipcd’ related trace/logs. You can purge these huge trace files if your Clusterware is well and has no issues. If required, you can keep the recent history and purge the rest. In addition, see Doc ID 25776294.8.

V$TRANSACTION lists the active transactions in the system.

(i) The following columns together point to a transaction. (i.e.) The combination of the following should give a unique transaction id for that database.

XIDUSN – Undo segment number
XIDSLOT – NUMBER Slot number
XIDSQN – NUMBER Sequence number

(ii) The following columns explain the number of undo blocks / undo records used per transaction.
USED_UBLK – Number of undo blocks used
USED_UREC – Number of undo records used

In the case of transaction rollback, the above columns will estimate the number of undo blocks that need to be rolled back.

The number of undo records and undo blocks (USED_UREC and USED_UBLK) decreases while the transaction rolls back. When they reach 0, the transaction disappears from v$transaction.

The following query can be used to monitor the transaction rollback.

(iii) The STATUS following column explains the status of a transaction.

ACTIVE – Explains the transaction is active.

Before performing a normal/transactional shutdown, YOU can check this view to understand any ACTIVE transactions.


For all offerings using Oracle Database 19c or later, if you are not licensed for Oracle Multitenant, then you may have up to 3 user-created PDBs in a given container database at any time. For all offerings using Oracle Database 12.1 through 18c, if you are not licensed for Oracle Multitenant, then the container database architecture is available in single-tenant mode, that is, with one user-created PDB, one user-created application root, and one user-created proxy PDB.

EE: Extra cost option; if you are licensed for Oracle Multitenant, then you can create up to 252 PDBs.

ODA and Exa: Extra cost option; if you are licensed for Oracle Multitenant, then you can create up to 4096 PDBs.

ExaCS/CC, DBCS EE-HP, and DBCS EE-EP: Included option; you can create up to 4096 PDBs.