Oracle Dba Online Test (MCQ) Advanced Level ASM

Oracle Database 19c Features

 Oracle Database 19c Features

Introduction

Oracle Database 19c is the long term release of the Oracle Database 12c and 18c family of products,it is available on all platformsWindows,Linux,Solaris,HP/UX and AIX as well as the Oracle cloud. Oracle Database 19c offers customers the best performance,scalibility,reliability, and security for all their operational and analytical workloads

Installation

Rpm based Installation install oracle 19c datbase using RPM method

Simlified image based installation of client as well

Upgrades

Auto Upgrade Utility for oracle Database

Docker Container for oracle 19c

Dryrun mode for Gridsetup in clusterware installation

General

Clear Flashback logs from time to time

Passwords removed from user accounts (default accounts)

Flush Metadata Cache for passwords

Multi-model partitioning with hybrid partioning allowing some partitions in database and some as external partitions even in HDFS

New ALTER SYSTEM  statement clause FLUSH PASSWORDFILE_METADATA_CACHE

Hybrid  Partitioned tables - to integerate internal partitions and external partitions  into a single partition table. partitions to reside in both oracle database segments and in external files and sources

Schema-only accounts -Passwords Removed from oracle database accounts  

Database Performance

SQL Quarantine - using Oracle's Resource manager tool is a great way to make sure SQL statements dont become resource hogs and slow down database performance everyone,if a system asks for more system resorces than the DBA allows ,Resources manager kills it,However in existing versions of oracle database,nothing stops users from executing problematic SQL statements again. In oracle 19C ,Resource manager can automatically quarantine the statements, user try to issue once again it wont be run at all

Automatic Indexing

This new feature puts oarcale automation capabilities to work.if oracle 19c thinks a database table would be benifit from an index,the system will automatically create the index and initially mark it as invisible so it cant be used .oracle 19c will then run SQL statements  from your application to see if the index improves query execution you can control this feature  with DBMS_AUTO_INDEX< a new PL?SQL package that's included in 19c

SQL Statement Diagnosability 

SQL Statement Diagnosability with SQL Advisor repair and SQL Test case for procedures

Automatic Database Diagnostic Monitor(ADDM)

ADDM supports for pluggable Database (PDB'S)

Realtime  Statastics For DML Operations

Oracle database 19c intoduces real time statastics which extend online support to conventional DML statements

Automatic Flashback of Standby Database

in prior versions DBA's wanted touse oracle flashback features to return  aprimary database to previous state,In oracle 19c ,a DBA can put the standby database in MOUNT mode with no managed recovery and then flashback the primary one ,the standby will aslo be reverted,thus keeping it in sync with the primary Statistics Collection on custom frequency automatically From 19c database onwards ,High frequency automatic optimizer statastics collection complements the standard statasticscollection job

DataPump

Oracle data pump test mode for transportable tablespace(TTS)

Oracle data pump allows tablespace to stay read -only during TTS import

Oracle data pump import supports more object store credentials

Oracle data pump ability to exclude ENCRYPTION clause on import-new transform  parameter OMIT_ENCRYPTION_CLAUSE

Oracle data pump support for resource usage limitations_new parameter MAX_DATAPUMP_PARALLEL_PER_JOB

Oracle data pump prevents inadvertent use of protected roles-new ENABLE_SECURE_ROLES parameter is available

Oracle data pump loads partitioned table data one operation-GROUP_PARTITION_TABLE_DATA,  new value for the import DATA_OPTIONS Command line paramaeter

Pluggable Databases

Create Duplicate of an oracle database create duplicatedb command , in DBCA silent mode

Ability to relocate a PDB to another CDB using DBCA in silent mode

Create a PDB by cloning a remote PDB using DBCA in silent mode

ADDM Analysis at PDB level

Data Guard

Replicate Restore points from primary to standby

Dynamically change  fast-start- failover (FSFO) target standby database to another standby database in the target list without disabling FSFO

Re-creation of broker configuration

Propagate restore points from primary to standby site

DML redirect to standby/ADG for read mostly applications

Simplified Dataguard broker parameter configurations

Observe only mode for data guard broker fast-satrt failover (FSFO)

Oracle dataguard multi-instance redo apply works with the in-memory column store

Finer granularity supplemental logging for logical standby databases

New Initialization Parameters in Oracle Database 19c 

"-optimizer_gather_stats_on_conventional_dml" and " _optimizer_use_stats_on_conventional_dml" which are true by default

-optimer_stats_on_conventional_dml_sample_rate(at 100%)

DATA_GUARD_MAX_IO_TIME

DATA_GUARD_MAX_LONGIO_TIME

MAX_DATAPUMP_JOBS_PER_PDB

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Flashback technology Recover a Dropped User in Oracle

Flashback technology  Recover a dropped user in oracle

Introduction

Using Flashback Technology  we can restore the dropped user in oracle we will flashback the database to past when the user is available at the time of dropped before,

Then take the export dump of the schema and restore the database to same current state once database is up we can import the dump file  

Prerequisites

1. Database must be Archivelog mode

2.Flash back must be enable for the database

3.All the flashback log and  Archive log should be available from the time the user is dropped 

Let us start the process

1.Make sure flashback and archive mode is enable.

SQL> select flashback_on,log_mode from v$database;

 

FLASHBACK_ON       LOG_MODE

------------------ -------------------------------

YES                                 ARCHIVELOG

2. lets drop the user and test the scenarios

04:47:15 SQL> select table_name from Chaitu_table where owner='CHAITANYA';

 

TABLE_NAME

----------------------------------------------------------------------------

ACCTTABLE1

MASTERTABLE2

 

 

04:47:33 SQL> drop user CHAITANYA cascade;

 

User dropped.

3.Flashback the database past when the user was available at that time

04:52:15 SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

04:52:50 SQL> startup mount;

ORACLE instance started.

 

Total System Global Area 1.1107E+10 bytes

Fixed Size                  7644464 bytes

Variable Size            9294584528 bytes

Database Buffers         1711276032 bytes

Redo Buffers               93011968 bytes

Database mounted.

 

04:53:08 SQL> flashback database to timestamp to_date('20-AUG-2020 04:47:33','DD-MON-YYYY HH24:MI:SS');

 

Flashback complete.

4. Open the database in readonly mode

04:55:13 SQL> ALTER DATABASE OPEN READ ONLY;

 

Database altered.

 

04:55:31 SQL>  select table_name from chaitu_tables where owner='CHAITANYA';

 

TABLE_NAME

--------------------------------------------------------------

ACCTTABLE1

MASTERTABLE2

we can see the tables are available now

5. Take export backup of the schema CHAITANYA

# exp owner=CHAITANYA file=chaitanya.dmp

 

Export: Release 12.1.0.2.0 - Production on Tue Aug 20 05:17:45 2020

 

Copyright (c) 1982, 2014, Oracle and/or its affiliates.  All rights reserved.

 

 

Username: / as sysdba

 

Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production

With the Partitioning, OLAP, Advanced Analytics, Real Application Testing

and Unified Auditing options

Export done in US7ASCII character set and AL16UTF16 NCHAR character set

server uses AL32UTF8 character set (possible charset conversion)

 

About to export specified users ...

. exporting pre-schema procedural objects and actions

. exporting foreign function library names for user CHAITANYA

. exporting PUBLIC type synonyms

. exporting private type synonyms

. exporting object type definitions for user CHAITANYA

About to export CHAITANYA's objects ...

. exporting database links

. exporting sequence numbers

. exporting cluster definitions

. about to export CHAITANYA's tables via Conventional Path ...

. . exporting table                           ACCTTABLE1     75341 rows exported

EXP-00091: Exporting questionable statistics.

. . exporting table                          MASTERTABLE2        44 rows exported

EXP-00091: Exporting questionable statistics.

. exporting synonyms

. exporting views

. exporting stored procedures

. exporting operators

. exporting referential integrity constraints

. exporting triggers

. exporting indextypes

. exporting bitmap, functional and extensible indexes

. exporting posttables actions

. exporting materialized views

. exporting snapshot logs

. exporting job queues

. exporting refresh groups and children

. exporting dimensions

. exporting post-schema procedural objects and actions

. exporting statistics

Export terminated successfully with warnings.

6. Now restore the database to current state

SQL> shutdown immediate;

Database closed.

Database dismounted.

ORACLE instance shut down.

SQL> startup mount

ORACLE instance started.

 

Total System Global Area 1.1107E+10 bytes

Fixed Size                  7644464 bytes

Variable Size            9294584528 bytes

Database Buffers         1711276032 bytes

Redo Buffers               93011968 bytes

Database mounted.

 

SQL> recover database;

Media recovery complete.

 

SQL> alter database open;

 

Database altered.

7. create the empty user and import the dumpfile

SQL> create user chaitanya identified by chaitanya;

 

User created.

 

SQL> grant connect,resource to chaitanya;

 

Grant succeeded.

 

# imp file=chaitanya.dmp fromuser=CHAITANYA TOUSER=CHAITANYA

 

Import: Release 12.1.0.2.0 - Production on Tue Aug 20 05:23:59 2020

 

Copyright (c) 1982, 2014, Oracle and/or its affiliates.  All rights reserved.

 

Username: / as sysdba

 

Connected to: Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production

With the Partitioning, OLAP, Advanced Analytics, Real Application Testing

and Unified Auditing options

 

Export file created by EXPORT:V12.01.00 via conventional path

import done in US7ASCII character set and AL16UTF16 NCHAR character set

import server uses AL32UTF8 character set (possible charset conversion)

. importing DBACLASS's objects into DBACLASS

. . importing table                        " ACCTTABLE1 "      75341 rows  imported

. . importing table                        "MASTERTABLE2"          44 rows imported

 we can restore the schema user chaitanya by using flashback technology

Note : Info on Flashback technology it may be differ in your environment like production,testing ,development and naming conventions 

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Recycle Bin in Oracle Database

 Recycle Bin in Oracle Database

Introduction

In windows  have a recycle bin to all deleted files will be store like wise in oracle database also 

provided recycle bin which keeps all the dropped objects.

When we drop a table (DROP TABLE TABLE_NAME) in the database , The tables will logically be

 removed but it still exists in the same tablespace 

but with a prefix BIN$$ .And it will not release the space also

Note : The Recycle bin which will not work sys owned objects it will worked on user objects only

If we drop a table using purge command, tables willbe removed completely (even from recycle bin also)

How to check the recycle bin is on or off

1.SQL> show parameter recyclebin;

 

NAME                                 TYPE        VALUE

------------------------------------ ----------- ------------------------------

recyclebin                           string      on

 

SQL> select name,value from v$parameter where name like '%recyclebin%';

 

NAME         VALUE

------------ ------------

recyclebin   on

2.Drop a table and check the table is there in the recycle bin or not  

SQL> drop table chaitanya.CHAITUTABLE;

 

Table purged.

 

SQL> select owner,OBJECT_NAME,ORIGINAL_NAME,DROPTIME,CAN_UNDROP from dba_recyclebin where ORIGINAL_NAME='CHAITUTABLE';

 

OWNER              OBJECT_NAME                                   ORIGINAL_NAME      DROPTIME            CAN

------------------ --------------------------------------------- ------------------ ------------------- ---

CHAITANYA           BIN$fxhnqWVcPLTgVAAQ4B8y7Q==$0                CHAITUTABLE         2020-01-10:12:45:03 YES

Now the table is in recycle bin we can recover the table if required

3. For purging the table for recyclebin

  in order to remove the table from recyclebin also

SQL> purge table chaitanya.CHAITUTABLE;

 

Table purged.

 

SQL>  select owner,OBJECT_NAME,ORIGINAL_NAME,DROPTIME,CAN_UNDROP from dba_recyclebin where ORIGINAL_NAME='CHAITUTABLE';

 

no rows selected

4. To purge complete recyclebin

SQL> select count(*) from dba_recyclebin;

 

  COUNT(*)

----------

       102

 

SQL> purge recyclebin;

 

Recyclebin purged.

 

SQL>  select count(*) from dba_recyclebin;

 

  COUNT(*)

----------

         0

5. To drop a table without keeping in recyclebin

SQL> select count(*) from CHAITANYA.chaitusample;

 

  COUNT(*)

----------

     82269

 

SQL> drop table CHAITANYA.CHAITUSAMPLE purge;

 

Table dropped.

 

SQL> select owner,OBJECT_NAME,ORIGINAL_NAME,DROPTIME,CAN_UNDROP from dba_recyclebin where ORIGINAL_NAME='CHAITUSAMPLE';

 

no rows selected

Note : Info on Recycle bin in oracle it may be differ in your encironment like production, testing,development and naming conventions 

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Hot and Cold Backup in Oracle

 Hot and Cold Backup in Oracle

Introduction

In Oracle basically we use either offline or Online backups, Offline backup is called as COLD backup and online backup is called HOT backup

Backups are two types---> Physical ------>Files(Control file,Data Files,Redolog files)

                                     |---->Logical--------->Data

These Data/Files need to protect from any disaster for that we need to manage backups

Physical Backup: physical backups will have interms of Files using Hot and Cold backup we can take backups

Cold Backup:

Cold backup is a physical backup in which all the files of a  database are copied without any change means it avoids the risk of copying data and hence the image copy is 

can be easily moved to another system having the same operating system,it is the safest way of take back up of All data in the database that is controlfile(.ctl files),Datafiles(.dbf files)

and Redolog files(.logfiles) Cold back are not recommended to take backup for larger databases it will take more time and space consumption client will not accept down time

Process

While taking cold backup 

Shutdown the instances

Complete full consistent backup

Traditional backup

Steps

1. Shutdown instances

2.Copy the Physical files using unix cp command

Note: /orabackup/prod/cold

$ mkdir -p /orabackup/prod/cold

shutdown immediate

Taking db files backup

$ cp /oradata/prod/*.dbf         /orabackup/prod/cold

or

$ cp /oradata/prod

$cp * /orabackup/prod/cold

Taking Control files backup

$ cp /oradata/prod/*.ctl        /orabackup/prod/cold

or

$ cp /oradata/prod

$cp * /orabackup/prod/cold

Taking redolog files backup

$ cp /oradata/prod/*.log        /orabackup/prod/cold

or

$ cp /oradata/prod

$cp * /orabackup/prod/cold

Hot Backup

Hot backup is also physcial backup including the risk of copying data because during the hot backup the database is totally open and available for users that is online.when a full backup of database is required for the hotbackup

 database must be running in the ARCHIVELOG mode, 

Is a inconsistent backup

is incomplete backup

is  a traditional backup

while hot backup ,database must be up and running also database be in archivelog mode,while in hot backup mode ,The database must be freezed can read but cannot write into datafiles so the changes are written into archivelog files tills ends,once the backup ended ,the changes are recovered into datafiles from archivelog

Process

1.archivelog mode

2.begin backup mode

3.copy the files

4.end backup

1. SQL> archive log list

2. SQL> select files #,status from v$backup;

3. SQL> alter database begin backup;

4. $ cp /oradata/prod/*.dbf   /orabackup/prod/hot

5.SQL> alter database end backup

6 . SQL> alter database  backup controlfile to '/orabackup/prod/hot/control01.bkp' ;

Note : Info on hot and cold backup it may be differ in your environment like production,testing,development and directory structures and naming conventions

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Oracle DBA Online Test(MCQ) Intermediate Level

 

Oracle Network Configuration Files

Oracle Network Configuration Files 

Introduction:

To communicate with other systems (server machines to client machines or client machines  to server machines)  we need three network configuration files in order to communicate with the systems  in oracle  three files need to configure that is listener.ora,tnsnames.ora,sqlnet.ora,oracle net enables a network connection between a client and database server oracle net is a software component that resides on both the client  and the database server.oracle net is layered on top of a network protocol -rules that determine how applications access the network and how data is subdivided into packets for transmission across the network . 

The example files below are relevant for an Oracle installation and instance with the following values.

• HOST : chaitanyaoracledba.blogspot.com

• ORACLE_HOME : /u01/app/oracle/product/12.1.0.2/db

• ORACLE_SID : orcl

• Service : orcl

• DOMAIN : blogspot.com

listener.ora

The "listerner.ora" file contains server side network configuration parameters. It can be found in the "$ORACLE_HOME/network/admin" directory on the server. Here is an example of a basic "listener.ora" file from Linux. We can see the listener has the default name of "LISTENER" and is listening for TCP connections on port 1521. Notice the reference to the hostname "chaitanyaoracledba.blogspot.com". If this is incorrect, the listener will not function correctly.

LISTENER =

  (DESCRIPTION_LIST =

    (DESCRIPTION =      

      (ADDRESS = (PROTOCOL = TCP)(HOST = chaitanyaoracledba.blogspot.com)(PORT = 1521))

    )

  )

After the "listener.ora" file is amended the listener should be restarted or reloaded to allow the new configuration to take effect.

$ # Restart

$ lsnrctl stop

$ lsnrctl start

$ # Or Reload.

$ lsnrctl reload

The listener defined above doesn't have any services defined. These are created when database instances auto-register with it. In some cases you may want to manually configure services, so they are still visible even when the database instance is down. If this is the case, you may use a "listener.ora" file like the following.

LISTENER =

  (DESCRIPTION_LIST =

    (DESCRIPTION =

      (ADDRESS = (PROTOCOL = TCP)(HOST = chaitanyaoracledba.blogspot.com)(PORT = 1521))

    )

  )

SID_LIST_LISTENER =

  (SID_LIST =

    (SID_DESC =

      (GLOBAL_DBNAME = orcl.blogspot.com)

      (ORACLE_HOME = /u01/app/oracle/product/12.1.0.2/db)

      (SID_NAME = orcl)

    )

  )

If there are multiple database instances on the server, you can added multiple SID_DESC entries inside the SID_LIST section.

tnsnames.ora

The "tnsnames.ora" file contains client side network configuration parameters. It can be found in the "$ORACLE_HOME/network/admin" directory on the client. This file will also be present on the server if client style connections are used on the server itself. Here is an example of a "tnsnames.ora" file.

LISTENER = (ADDRESS = (PROTOCOL = TCP)(HOST = chaitanyaoracledba.blogspot.com)(PORT = 1521))

orcl.blogspot.com =

  (DESCRIPTION =

    (ADDRESS_LIST =

      (ADDRESS = (PROTOCOL = TCP)(HOST = chaitanyaoracledba.blogspot.com)(PORT = 1521))

    )

    (CONNECT_DATA =

      (SERVICE_NAME = orcl)

    )

  )

The alias used at the start of the entry can be whatever you want. It doesn't have to match the name of the instance or service. Notice the PROTOCOL, HOST and PORT match that of the listener. The SERVICE_NAME can be any valid service presented by the listener. You can check the available services by issuing the lsnrctl status or lsnrctl service commands on the database server. Typically there is at least one service matching the ORACLE_SID of the instance, but you can create more.

sqlnet.ora

The "sqlnet.ora" file contains client side network configuration parameters. It can be found in the "$ORACLE_HOME/network/admin" directory on the client. This file will also be present on the server if client style connections are used on the server itself, or if some additional server connection configuration is required. Here is an example of an "sqlnet.ora" file.

NAMES.DIRECTORY_PATH= (TNSNAMES, ONAMES, HOSTNAME)

NAMES.DEFAULT_DOMAIN = blogspot.com

# The following entry is necessary on Windows if OS authentication is required.

SQLNET.AUTHENTICATION_SERVICES= (NTS)

There are lots of parameters that can be added to control tracing, encryption, wallet locations etc. These are out of the scope of this article.

Testing

Once the files are present in the correct location and amended as necessary the configuration can be tested using SQL*Plus by attempting to connect to the database using the appropriate username (SCOTT), password (TIGER) and service (orcl.blogspot.com).

$ sqlplus scott/tiger@orcl.blogspot.com

Common Problems

The OS hostname command must return the correct hostname of your database server. If not, fix it so it does.

$ hostname

chaitanyaoracledba.blogspot.com

$

The server must have a correct entry in the "/etc/hosts" file matching the hostname and IP address of the server, as well as the loopback entry for localhost. For example in this case the values are as follows.

127.0.0.1      localhost localhost.localdomain localhost4 localhost4.localdomain4

192.168.0.100  chaitanyaoracledba.blogspot.com  chaitanyaoracledba

 If these are provided by DNS, that is fine also.

If you are using the ORACLE_HOSTNAME environment variable, possibly set in your "/home/oracle/.bash_profile", it must be set to the correct value.

export ORACLE_HOSTNAME=chaitanyaoracledba.blogspot.com

The HOST entry in the "listener.ora" file must point to an active network adapter, either real or loopback. If not, the listener will fail to start.

If the HOST entry in the "listener.ora" file is set to "localhost", the listener will start and accept connections from the local server, but not from other clients. You would typically expect this to be set to the hostname of the database server, although some people use the IP address instead.

For the client to make a connection via the listener, there must be a clear route through the network between the two machines. If you are struggling to connect, check network firewalls and the local firewall (iptables, firewalld, Windows Firewall) on the database server.

Tools for Network configuration

Oracle enables you to manage your network configuration with the following tools

Oracle Net Configuration Assistant

Enterprise manager

Oracle Net Manager

Oracle Net Configuration Assistant:  The oracle universal installer launches Oracle Net Configuration Assistant after the database is installed use oracle net configuration assistant to configure the listening protocol address and service information for an oracle database,during a typical database install,oracle net configuration assistant automatically configures a listener called LISTENER that has TCP/IP listening protocol address for the database.Oracle Net Configuration assistant prompts you to configure a listener name and protocol address of your choice.

use Oracle Network Configuration Assistant for initial network configuration after database installation there after you can use the Oracle Enterprise Manager and Oracle Net Manager to configure and administer your network

Oracle Net Manager:

You can access Oracle Net Manager from the command line or for windows platforms through the start menu

 command line (Unix,Linux or windows )run netmgr

on windows click the start button and select programs,oracle-oracle_home,configuration and migration tools, and then Net Manager  

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