Oracle Tidbits – July 2016

Oracle *daily* TidBits” (#oratidbit) published at on weekdays in July 2016. You will also see these tidbits, one tidbit at a time, for each page refresh on the right side of this blog as well… Hope you find these helpful to learn something new or to remind you of its existence and use…

#oratidbit Oracle SQL Connector for Hadoop Distributed File System (Oracle SQL Connector for HDFS) provides read access to HDFS from an Oracle database using external tables.
#oratidbit Direct upgrade to 12c is possible if your current Oracle Database is release,, or release or later. You may directly upgrade from release to
#oratidbit Starting with Oracle Database 12c, non-rolling upgrades for Oracle Real Application Clusters require Oracle Clusterware on the local node to be up and running.
#oratidbit On Windows systems, Oracle Universal Installer (OUI) sets environment variables such as PATH, ORACLE_BASE, ORACLE_HOME, and ORACLE_SID in the registry during installation. On Linux and UNIX systems, you must manually set these environment variables.
#oratidbit On Windows systems, Oracle Universal Installer (OUI) creates the ORA_DBA, ORA_OPER, ORA_HOMENAME_DBA, and ORA_HOMENAME_OPER groups, which are used for operating system authentication for Oracle instances. On Linux and UNIX systems, you must create the operating system groups manually.
#oratidbit On the Windows platform, to upgrade Oracle Clusterware from releases and to release 12.1, you must perform an interim upgrade to for Oracle Clusterware. After upgrading Oracle Clusterware to release, you must move the Oracle Cluster Registry (OCR) and voting disk (VDSK) to Oracle ASM.
#oratidbit Once installed, there is no simple command to change the Oracle cluster name. On windows you must reinstall Oracle Grid Infrastructure. On Linux, the process will require cluster outage and delete all GI resources, then run $GRID_HOME/crs/config/ script.
#oratidbit The location of the Oracle central inventory on Windows is always %SYSTEM_DRIVE%\Program Files\Oracle\Inventory. When you install Oracle software on the system, OUI creates the directories for the Oracle central inventory and the Oracle Inventory group, ORA_INSTALL.
‪#‎oratidbit‬ Transparent Data Encryption (TDE) enables you to encrypt data so that only an authorized recipient can read it. TDE automatically encrypts data when it is written to disk, and then automatically decrypts the data when applications access it.
#oratidbit Oracle Data Redaction enables you to redact (mask) column data, using full redaction, partial redaction, regular expressions, and random redaction. Data Redaction performs the redaction at runtime.
‪#‎oratidbit‬ You cannot create a Data Redaction policy for a multitenant container database (CDB). This is because the objects for which you create Data Redaction policies typically reside in a PDB.
#oratidbit The objective in tuning an Oracle database should be to reduce the time that users spend in performing an action on the database, or to simply reduce “DB time”. Time model statistics are accessible from the V$SESS_TIME_MODEL and V$SYS_TIME_MODEL views.
#oratidbit V$SYSMETRIC_SUMMARY shows a summary of system Metric values. The average, maximum value, minimum value, and the value of one standard deviation for the last hour are displayed for each metric item. Snapshots of this view is kept in AWR as DBA_HIST_SYSMETRIC_SUMMARY.
#oratidbit V$SYSMETRIC_HISTORY displays system metric values available in the database, with 1 hour history. Snapshots of this view is kept in AWR as DBA_HIST_SYSMETRIC_HISTORY.
#oratidbit In a Container database, the seed PDB is a system-supplied template that the CDB can use to create new PDBs. The seed PDB is named PDB$SEED. You cannot add or modify objects in PDB$SEED.
#oratidbit The CREATE DATABASE … ENABLE PLUGGABLE DATABASE SQL statement creates a new Container Database. If you do not specify the ENABLE PLUGGABLE DATABASE clause, then the newly created database is a non-CDB and can never contain PDBs.
#oratidbit If you start a database instance using the server parameter file (spfile) with the ORACLE_BASE environment variable set, then its value is automatically stored in spfile. If you unset the ORACLE_BASE environment variable and start the instance again, then the database uses the value of the Oracle base directory stored in spfile.
#oratidbit If you have set ORACLE_BASE for the oracle user during installation, then Oracle Universal Installer creates the Oracle Inventory directory one level above the ORACLE_BASE in the path ORACLE_BASE/../oraInventory.
#oratidbit For job separation, Oracle RDBMS installation lets you have many OS groups – OSDBA and OSOPER are standard groups. Extended group includes OSBACKUPDBA (backups), OSDGDBA (Data Guard), OSKMDBA (Key Management).
#oratidbit Oracle Grid Infrastructure for a standalone server includes Oracle Restart and Oracle Automatic Storage Management.
#oratidbit The script must be run if this is the first time you are installing Oracle software on your system. creates the inventory pointer file (/etc/oraInst.loc).

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