1z0-062 Oracle Database 12c: Installation and Administration Questions and Answers

References: https://docs.oracle.com/cd/B28359_01/server.111/b28320/initparams240.htm#REFRN10214

References https://docs.oracle.com/cd/B28359_01/server.111/b28300/expimp.htm#UPGRD12560

References: https://docs.oracle.com/database/121/DBSEG/audit_admin.htm#DBSEG370

References: https://docs.oracle.com/cd/B19306_01/server.102/b14231/schedover.htm

References: http://www.dba-oracle.com/t_segment_advisor_10g.htm

References: https://docs.oracle.com/cd/E11882_01/server.112/e18951/asm_rman.htm#OSTMG89995

* Oracle Database provides a mechanism to make table structure modifications without significantly affecting the availability of the table. The mechanism is called online table redefinition. Redefining tables online provides a substantial increase in availability compared to traditional methods of redefining tables.

* To redefine a table online:

Choose the redefinition method: by key or by rowid

* By key—Select a primary key or pseudo-primary key to use for the redefinition. Pseudo-primary keys are unique keys with all component columns having NOT NULL constraints. For this method, the versions of the tables before and after redefinition should have the same primary key columns. This is the preferred and default method of redefinition.

* By rowid—Use this method if no key is available. In this method, a hidden column named M_ROW$$ is added to the post-redefined version of the table. It is recommended that this column be dropped or marked as unused after the redefinition is complete. If COMPATIBLE is set to 10.2.0 or higher, the final phase of redefinition automatically sets this column unused. You can then use the ALTER TABLE ... DROP UNUSED COLUMNS statement to drop it.

You cannot use this method on index-organized tables.

Note:

* When you rebuild an index, you use an existing index as the data source. Creating an index in this manner enables you to change storage characteristics or move to a new tablespace. Rebuilding an index based on an existing data source removes intra-block fragmentation. Compared to dropping the index and using the CREATE INDEX statement, re-creating an existing index offers better performance.

Incorrect:

Not E: Edition-based redefinition enables you to upgrade the database component of an application while it is in use, thereby minimizing or eliminating down time.

References:

A single extent can never span data files.

https://docs.oracle.com/database/121/CNCPT/logical.htm#CNCPT1095

Keyword: shows the difference.

* Full ADDM analysis across two AWR snapshot periods

Detects causes, measure effects, then correlates them

Causes: workload changes, configuration changes

Effects: regressed SQL, reach resource limits (CPU, I/O, memory, interconnect)

Makes actionable recommendations along with quantified impact

* Identify what changed

/ Configuration changes, workload changes

* Performance degradation of the database occurs when your database was performing optimally in the past, such as 6 months ago, but has gradually degraded to a point where it becomes noticeable to the users. The Automatic Workload Repository (AWR) Compare Periods report enables you to compare database performance between two periods of time.

While an AWR report shows AWR data between two snapshots (or two points in time), the AWR Compare Periods report shows the difference (ABE) between two periods (or two AWR reports with a total of four snapshots). Using the AWR Compare Periods report helps you to identify detailed performance attributes and configuration settings that differ between two time periods.

References:

The stop_on_window_close attribute controls whether the GATHER_STATS_JOB continues when the maintenance window closes. The default setting for the stop_on_window_close attribute is TRUE, causing Scheduler to terminate GATHER_STATS_JOB when the maintenance window closes. The remaining objects are then processed in the next maintenance window.

References: https://docs.oracle.com/cd/B19306_01/server.102/b14211/stats.htm#g49431

* You can create a password file using the password file creation utility, ORAPWD.

* Adding Users to a Password File

When you grant SYSDBA or SYSOPER privileges to a user, that user's name and privilege information are added to the password file. If the server does not have an EXCLUSIVE password file (that is, if the initialization parameter REMOTE_LOGIN_PASSWORDFILE is NONE or SHARED, or the password file is missing), Oracle Database issues an error if you attempt to grant these privileges.

A user's name remains in the password file only as long as that user has at least one of these two privileges. If you revoke both of these privileges, Oracle Database removes the user from the password file.

* The syntax of the ORAPWD command is as follows:

ORAPWD FILE=filename [ENTRIES=numusers]

[FORCE={Y|N}] [IGNORECASE={Y|N}] [NOSYSDBA={Y|N}]

* IGNORECASE

If this argument is set to y, passwords are case-insensitive. That is, case is ignored when comparing the password that the user supplies during login with the password in the password file.

Manually Sized SGA Components that Use SGA_TARGET Space

SGA Component, Initialization Parameter

/ The log buffer

LOG_BUFFER

/ The keep and recycle buffer caches

DB_KEEP_CACHE_SIZE

DB_RECYCLE_CACHE_SIZE

/ Nonstandard block size buffer caches

DB_nK_CACHE_SIZE

Note:

* In addition to setting SGA_TARGET to a nonzero value, you must set to zero all initialization parameters listed in the table below to enable full automatic tuning of the automatically sized SGA components.

* Table, Automatically Sized SGA Components and Corresponding Parameters

You must specify the names and locations of the seed's files in one of the following ways:

* (A) Oracle Managed Files

* (B) The SEED FILE_NAME_CONVERT Clause

* (C) The PDB_FILE_NAME_CONVERT Initialization Parameter

1. Set user tablespaces in the source database to READ ONLY.

2. From the Oracle Database 11g Release 2 {11.2.0.3) environment, export the metadata and any data residing in administrative tablespaces from the source database using the FULL=Y and TRANSPORTABLE=ALWAYS parameters. Note that the VER$ION=12 parameter is required only when exporting from an Oracle Database llg Release 2 database:

3. Copy the tablespace data files from the source system to the destination system. Note that the log file from the export operation will list the data files required to be moved.

4. Create a COB on the destination system, including a PDB into which you will import the source database.

5. In the Oracle Database 12c environment, connect to the pre-created PDB and import the dump file. The act of importing the dump file will plug the tablespace data files into the destination PDB

Oracle White Paper - Upgrading to Oracle Database 12c -August 2013

About Altering the Default Full Data Redaction Value

You can alter the default displayed values for full Data Redaction polices. By default, 0 is the redacted value when Oracle Database performs full redaction (DBMS_REDACT.FULL) on a column of the NUMBER data type. If you want to change it to another value (for example, 7), then you can run the DBMS_REDACT.UPDATE_FULL_REDACTION_VALUES procedure to modify this value. The modification applies to all of the Data Redaction policies in the current database instance. After you modify a value, you must restart the database for it to take effect.

Note:

* The DBMS_REDACT package provides an interface to Oracle Data Redaction, which enables you to mask (redact) data that is returned from queries issued by low-privileged users or an application.

* UPDATE_FULL_REDACTION_VALUES Procedure

This procedure modifies the default displayed values for a Data Redaction policy for full redaction.

* After you create the Data Redaction policy, it is automatically enabled and ready to redact data.

* Oracle Data Redaction enables you to mask (redact) data that is returned from queries issued by low-privileged users or applications. You can redact column data by using one of the following methods:

/ Full redaction.

/ Partial redaction.

/ Regular expressions.

/ Random redaction.

/ No redaction.

References:

References:

http://docs.oracle.com/cd/A87860_01/doc/server.817/a76956/start.htm

The listener is used when the connection is established. The immediate impact of stopping the listener will be that no new session can be established from a remote host. Existing sessions are not compromised.

* Smart Flash Cache concept is not new in Oracle 12C - DB Smart Flash Cache in Oracle 11g.

In this release Oracle has made changes related to both initialization parameters used by DB Smart Flash cache. Now you can define many files|devices and its sizes for “Database Smart Flash Cache” area. In previous releases only one file|device could be defined.

DB_FLASH_CACHE_FILE = /dev/sda, /dev/sdb, /dev/sdc

DB_FLASH_CACHE_SIZE = 32G, 32G, 64G

So above settings defines 3 devices which will be in use by “DB Smart Flash Cache”

/dev/sda – size 32G

/dev/sdb – size 32G

/dev/sdc – size 64G

New view V$FLASHFILESTAT – it’s used to determine the cumulative latency and read counts of each file|device and compute the average latency

Use the CREATE PLUGGABLE DATABASE statement to create a pluggable database (PDB).

This statement enables you to perform the following tasks:

* (A) Create a PDB by using the seed as a template

Use the create_pdb_from_seed clause to create a PDB by using the seed in the multitenant container database (CDB) as a template. The files associated with the seed are copied to a new location and the copied files are then associated with the new PDB.

* (C) Create a PDB by cloning an existing PDB

Use the create_pdb_clone clause to create a PDB by copying an existing PDB (the source PDB) and then plugging the copy into the CDB. The files associated with the source PDB are copied to a new location and the copied files are associated with the new PDB. This operation is called cloning a PDB.

The source PDB can be plugged in or unplugged. If plugged in, then the source PDB can be in the same CDB or in a remote CDB. If the source PDB is in a remote CDB, then a database link is used to connect to the remote CDB and copy the files.

* Create a PDB by plugging an unplugged PDB or a non-CDB into a CDB

Use the create_pdb_from_xml clause to plug an unplugged PDB or a non-CDB into a CDB, using an XML metadata file.

A:

1. Get the list of all datafiles.

Note: RMAN Backup of ASM Storage

There is often a need to move the files from the file system to the ASM storage and vice versa. This may come in handy when one of the file systems is corrupted by some means and then the file may need to be moved to the other file system.

D: Migrating a Database into ASM

* To take advantage of Automatic Storage Management with an existing database you must migrate that database into ASM. This migration is performed using Recovery Manager (RMAN) even if you are not using RMAN for your primary backup and recovery strategy.

* Example:

Back up your database files as copies to the ASM disk group.

BACKUP AS COPY INCREMENTAL LEVEL 0 DATABASE

FORMAT '+DISK' TAG 'ORA_ASM_MIGRATION';

References:

Step 1 (2). Seed column usage

Oracle must observe a representative workload, in order to determine the appropriate column groups. Using the new procedure DBMS_STATS.SEED_COL_USAGE, you tell Oracle how long it should observe the workload.

Step 2: (3) You don't need to execute all of the queries in your work during this window. You can simply run explain plan for some of your longer running queries to ensure column group information is recorded for these queries.

Step 3. (1) Create the column groups

At this point you can get Oracle to automatically create the column groups for each of the tables based on the usage information captured during the monitoring window. You simply have to call the DBMS_STATS.CREATE_EXTENDED_STATS function for each table.This function requires just two arguments, the schema name and the table name. From then on, statistics will be maintained for each column group whenever statistics are gathered on the table.

Note:

* DBMS_STATS.REPORT_COL_USAGE reports column usage information and records all the SQL operations the database has processed for a given object.

* The Oracle SQL optimizer has always been ignorant of the implied relationships between data columns within the same table. While the optimizer has traditionally analyzed the distribution of values within a column, he does not collect value-based relationships between columns.

* Creating extended statisticsHere are the steps to create extended statistics for related table columns withdbms_stats.created_extended_stats:

1 - The first step is to create column histograms for the related columns.2 – Next, we run dbms_stats.create_extended_stats to relate the columns together.

Unlike a traditional procedure that is invoked via an execute (“exec”) statement, Oracle extended statistics are created via a select statement.

Oracle 11g/12c makes further use of SQL tuning sets with the SQL Performance Analyzer, which compares the performance of the statements in a tuning set before and after a database change. The database change can be as major or minor as you like, such as:

* (E) Database, operating system, or hardware upgrades.

* (A, C) Database, operating system, or hardware configuration changes.

* Database initialization parameter changes.

* Schema changes, such as adding indexes or materialized views.

* Refreshing optimizer statistics.

* Creating or changing SQL profiles.

Multipartition maintenance enables adding, dropping, truncate, merge, split operations on multiple partitions.

A: Merge Multiple Partitions:

The new “ALTER TABLE … MERGE PARTITIONS ” help merge multiple partitions or subpartitions with a single statement. When merging multiple partitions, local and global index operations and semantics for inheritance of unspecified physical attributes are the same for merging two partitions.

B: Drop Multiple Partitions:

The new “ALTER TABLE … DROP PARTITIONS ” help drop multiple partitions or subpartitions with a single statement.

Example:

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SQL> ALTER TABLE Tab_tst1 DROP PARTITIONS

Tab_tst1_PART5, Tab_tst1_PART6, Tab_tst1_PART7;

Table altered

SQL>

Restrictions :

- You can’t drop all partitions of the table.

- If the table has a single partition, you will get the error: ORA-14083: cannot drop the only partition of a partitioned.

A: Starting with 12c, Oracle has unified all of the auditing types into one single unit called Unified auditing. You don’t have to turn on or off all of the different auidting types individually and as a matter of fact auditing is enabled by default right out of the box. The AUD$ and FGA$ tables have been replaced with one single audit trail table. All of the audit data is now stored in Secure Files table thus improving the overall management aspects of audit data itself.

B: Further the audit data can also be buffered solving most of the common performance related problems seen on busy environments.

E: Unified Auditing is able to collect audit data for Fine Grained Audit, RMAN, Data Pump, Label Security, Database Vault and Real Application Security operations.

Note:

* Benefits of the Unified Audit Trail

The benefits of a unified audit trail are many:

/ (B) Overall auditing performance is greatly improved. The default mode that unified audit works is Queued Write mode. In this mode, the audit records are batched in SGA queue and is persisted in a periodic way. Because the audit records are written to SGA queue, there is a significant performance improvement.

/ The unified auditing functionality is always enabled and does not depend on the initialization parameters that were used in previous releases

/ (A) The audit records, including records from the SYS audit trail, for all the audited components of your Oracle Database installation are placed in one location and in one format, rather than your having to look in different places to find audit trails in varying formats. This consolidated view enables auditors to co-relate audit information from different components. For example, if an error occurred during an INSERT statement, standard auditing can indicate the error number and the SQL that was executed. Oracle Database Vault-specific information can indicate whether this error happened because of a command rule violation or realm violation. Note that there will be two audit records with a distinct AUDIT_TYPE. With this unification in place, SYS audit records appear with AUDIT_TYPE set to Standard Audit.

/ The management and security of the audit trail is also improved by having it in single audit trail.

/ You can create named audit policies that enable you to audit the supported components listed at the beginning of this section, as well as SYS administrative users. Furthermore, you can build conditions and exclusions into your policies.

* Oracle Database 12c Unified Auditing enables selective and effective auditing inside the Oracle database using policies and conditions. The new policy based syntax simplifies management of auditing within the database and provides the ability to accelerate auditing based on conditions.

* The new architecture unifies the existing audit trails into a single audit trail, enabling simplified management and increasing the security of audit data generated by the database.

References: https://docs.oracle.com/database/122/CNCPT/process-architecture.htm#CNCPT9840

References: https://docs.oracle.com/cd/B13789_01/server.101/b10734/rcmbackp.htm

References: http://www.juliandyke.com/Research/RMAN/BackupCommand.php

References:

http://www.oracle.com/technetwork/database/manageability/emx-intro-1965965.html

A, Not D: In a CDB, PUBLIC is a common role. In a PDB, privileges granted locally to PUBLIC enable all local and common users to exercise these privileges in this PDB only.

C: A user can only perform common operations on a common role, for example, granting privileges commonly to the role, when the following criteria are met:

The user is a common user whose current container is root.

The user has the SET CONTAINER privilege granted commonly, which means that the privilege applies in all containers.

The user has privilege controlling the ability to perform the specified operation, and this privilege has been granted commonly

Incorrect:

Note:

* Every privilege and role granted to Oracle-supplied users and roles is granted commonly except for system privileges granted to PUBLIC, which are granted locally.

Unlike unusable indexes, an invisible index is maintained during DML statements.

Note:

* Oracle 11g allows indexes to be marked as invisible. Invisible indexes are maintained like any other index, but they are ignored by the optimizer unless the OPTIMIZER_USE_INVISIBLE_INDEXES parameter is set to TRUE at the instance or session level. Indexes can be created as invisible by using the INVISIBLE keyword, and their visibility can be toggled using the ALTER INDEX command.

Note:

* Oracle 12c now provides the ability to index a subset of partitions and to exclude the others.

Local and global indexes can now be created on a subset of the partitions of a table. Partial Global indexes provide more flexibility in index creation for partitioned tables. For example, index segments can be omitted for the most recent partitions to ensure maximum data ingest rates without impacting the overall data model and access for the partitioned object.

Partial Global Indexes save space and improve performance during loads and queries. This feature supports global indexes that include or index a certain subset of table partitions or subpartitions, and exclude the others. This operation is supported using a default table indexing property. When a table is created or altered, a default indexing property can be specified for the table or its partitions.