In previous article we saw the process for creating Container and Pluggable Databases using Database Configuration Assistance (DBCA). There are difference in connecting to pluggable database as compared to those of container database and databases in previous releases. Also the way we need startup and shutdown the pluggable database.
It is really surprising and interesting to know, when we start the container database, all the pluggable database within are automatically mounted. There is no special mechanism to start pluggable database when we start the container database. We can manage the pluggable database in two ways:
Connecting to Container Database
We created the container database named CBD.
To check the services under container database, and information of which pluggable database it holds, you can use the dictionary view V$SERVICES
To get the details of all the services, you can use “lsnrctl” utility
You can get the details of current container with 2 methods as show:
You can switch to container inside container simply with “Alter Session Set” Command as:
Connecting to pluggable database
You can connect to pluggable database using “tnsname” or direct connect using service name. Connect to database and make sure that you are connected to appropriate database as:
Start up and Shut Down Pluggable database.
Startup and Shutdown process is simple as that of databases of previous releases. There is difference in managing pluggable database. When connected to container database, you can use “Alter Pluggable database” statements to manage the database. Some examples of the same are given below.
Following are possible options to perform startup operations on pluggable database:
ALTER PLUGGABLE DATABASE <pdb_name>OPEN READ WRITE [RESTRICTED] [FORCE];
ALTER PLUGGABLE DATABASE <pdb_name> OPEN READ ONLY [RESTRICTED] [FORCE];
ALTER PLUGGABLE DATABASE <pdb_name> OPEN UPGRADE [RESTRICTED];
ALTER PLUGGABLE DATABASE <pdb_name> CLOSE [IMMEDIATE];
If you have multiple pluggable database, “Alter Pluggable Database” can be used manage one or more database with single command. You need to specify the names of pluggable database as below:
ALTER PLUGGABLE DATABASE <pdb_1_name>,<pdb_2_name> [OPEN]/[CLOSE];
In case your container has few pluggable database and you wish to keep some of them shutdown and start rest you can use “Alter Pluggable database…EXPECT” command, as:
ALTER PLUGGABLE DATABASE ALL EXPECT pdb OPEN;
As said earlier that there is no special mechanism to start pluggable database when we start the container database, but we can achieve that creating the trigger on container database when starts to perform the startup of the pluggable databases automatically within it.
CREATE OR REPLACE TRIGGER openallpluggabledatabases
AFTER STARTUP ON DATABASE
EXECUTE IMMEDIATE ‘ALTER PLUGGABLE DATABASE ALL OPEN’;
This was all about connecting and managing startup/shutdown of pluggable databases. In coming article we shall understand how to view the information/properties of container and pluggable database using data dictionary view or SQL*Plus.
NoSQL or Non-Relational DBMS is the recent buzz in models for data storing and retrieving data. As any other database management system the sole purpose NoSQL is also simplification and consistency in data management. RDMBS have ruled the data management sector for over 4 decades and has been promising till date. Then where and how does NoSQL stands apart and what is the need to design new DBMS. The intent of NoSQL is to provide the more consistent model than traditional management systems. The inspiration behind the concept is to provide the horizontal scalability and fine control over high availability. NoSQL database are significantly used in big data and real-time web application systems.
So what are the difference between two models? Let us walk first have walk through relational or also called structured model of databases. Structured database have their hard coded rules that govern the atomicity, consistency, integrity and durability (ACID). If any of the property is not met or violated the database is prohibited and needs attentions. Now in case of NoSQL, ACID property is turned up-side-down. How? NoSQL follows BASE property. Unlike ACID it is not the set of property but simple guidelines. BA-basic availability, S-soft state and E-eventual consistency.
Unlike structured database, data in NoSQL is stored in Key-Value format. No need to create the table and store the data in multiple rows with some primary key- foreign key. Simply store value for each individual key, store in database, and allow simple retrieval. It’s interesting to know if there no table in database, then where and how data is stored. Here it is learn understand the beauty of the architecture, which very simple and easy to understand.
The NoSQL database uses the hash function at core level – a well know algorithm that takes a variable length input and gives fixed-length consistent output. The key of every key-value pair provided to a NoSQL database is hashed and this hash value is used to direct the pair to a particular NoSQL database server, where the record is stored and retrieved as required. When any application request for data retrieval for key value pair, the key is provided to database as an input. This key is then hashed again to find the appropriate server where the data would be stored (if the key exists in the database) and then the database engine retrieves the key-value pair from that server.
There are different type of NoSQL Databases viz. Key-Value Store NoSQL Databases, Document Stores NoSQL Database, Graph Store NoSQL Database and Columnar Stores NoSQL Databases.
No doubt NoSQL provides and promises more than traditional database management system, but the concept had lot more to prove before replacing relation databases completely. If we can see limitations in RDBMS, for sure there are many limitation with NoSQL has. But yes for sure NoSQL has bright future ahead in lightweight data storage in highly efficient and consistent manner.
Now-a-days businesses are moving and adapting cloud services at a rapid speed. Cloud Computing is changing the way of IT resources being used. In fact, a recent study conducted by KPMG found that 81% of businesses were either assessing cloud services, planning for a cloud adoption or had already implemented a cloud solution. No matter how businesses decide to move to the cloud, one thing is obvious: they are moving to the cloud solutions.
Business realized various benefits of cloud. It facilitates business scalability, agility, innovations, instant provisioning and flexibility with better load distribution without increasing IT budget. For this reason, in order to achieve flexibility and to attain on time IT support, most of the organizations are moving their applications to cloud.
When you host your website “on premise,” you are responsible for running and managing IT resources i.e. servers, racks, networking gear, electricity, bandwidth, redundancy and more. Alternatively, you can host your website with a cloud provider instead of filling up your office with servers, cooling systems etc. as the cloud host takes care of that work. What you need to do? You just sit back, relax and take advantages of scalable environment.
So what are the advantages of hosting your website on cloud?
Availability and Reliability
24×7 support by in-house experts, as your website is hosted on cloud.
The excuse that more companies continue to cling to ignore the implementation of a document management system is invariably in the price.
It is based on the amounts they have to pay, that the majority of companies, especially small and medium enterprises (SMEs), apologize for not taking the necessary steps in terms of ease and effectiveness in managing documentation, to levels that can make all the difference to their business processes.
A novelty for those companies that prefer to say is scared by the costs of document management: A management system for documentation can be cheap, very cheap.
There are document management applications that comes at very competitive prices.
Especially systems that are based on open source software, developed for the Linux operating systems and programming tools and open-source databases, not lead to additional costs with software licenses, which translates into huge savings over proprietary systems.
Often gives up to the event, the company, the acquisition of the document management system, become the holder of alternative systems that cause may be exempted systems that must be purchased separately.
It is the case of software that acts as Electronic Mail Server, File Server, Fax Server and Printer.
That is to rethink whether it is preferable to use these strategies to manage shared email documentation and continue with much sand in the wheels, instead of adopting a true document management tool.
As an Oracle DBA, while working upon high availability of your database you may come across various Oracle strategic capabilities that fall into categories of Oracle Replication. Oracle provides various technologies for replication like golden gate, streams, and active dataguard. Replication being the primary purpose of all the mentioned technologies, have different internal operational behavior. The purpose is to achieve maximum database availability, these mentioned technologies fully accommodate the requirement but internally there are differences at internal operational level. DBA must learn and understand functionality of both and know which technique can be used and in what scenario?
Oracle Active Dataguard is simple and the most economical solution for replication. The concept of active dataguard is super set of traditional dataguard. It offers real time data protection and availability. Here in active replication you can place your secondary database in read-only mode, where secondary database is available to users for limited usage like reporting and query offloading. Active Dataguard promises zero data loss across large distances without hampering performance. Other benefits to count on you can consider the capability of Active Dataguard to automatically repair the physical corruption without incurring any performance impact and availability of the dedicated servers. Using special purpose network devices Active Dataguard ensure minimal bandwidth utilizations. With Active Dataguard DBAs can reduce the planned downtime to much extent while migrating or upgrading databases.
Oracle Golden Gate is most advanced logical replication product from Oracle. This is especially well known for its cross-platform operating capabilities. Golden Gate provides wide range of options addressing customer’s number of replication needs. The basic principal it works up on is to capture online changes, distribute and deliver transactions across various secondary system. The secondary database in this configuration is available is read-write mode during replication and synchronizations, incurring additional overhead to maintain both database in same state. The beauty of Golden Gate lies in its capability to replicate the changes in heterogeneous IT environment taking into consideration all the components of IT along with various Database Management Systems. We can rely on the technology even in case of network outage between primary and secondary server located geographically at long distances. The recent release of product promises improved performance, reliability, consistency, conflict detections, data integrity etc.
It is really important to understand the feasibility of solution taking into consideration financial aspect of the organization while selecting appropriate solution. Below are some comparison points that can let us decide which technology can be used to meet our requirements:
1. Use of Secondary Server: if there is any need to update the secondary server, you can do with Golden Gate. Database is available in read-write mode and users can perform operation on the database. Whereas the database in case of Active Dataguard is open in read-only mode.
2. Supplemental Logging: With Active Dataguard you need not require to put on the supplemental logging for tables not having primary keys or unique indexes. Some configurations and settings with minimal performance overhead active dataguard handles most workload. Golden Gate compulsory requires supplemental logging tables with without primary key and unique indexes.
3. Maintenance & Migrations: Oracle Golden Gate provides the zero-downtime using 2way or bi-directional replication. Whereas there are some scenarios where reduced downtime for various planned activities is not possible with Active Dataguard.
4. Cross-Edition migrations & replication: Golden Gate ensures the cross-platform replication and migration with zero-downtime. Active Dataguard requires the configuration to have same editions of database on the same operating platform on both primary and secondary environment. That means any cross-platform migration or replication is not provided by Active Dataguard.
5. Version backward Compatibility: Golden Gate is flexible enough to support the previous releases for replicating data from newer version or release. That means data of Oracle 11g can be replicated on Oracle 10g database.
Depending upon the requirements we can chose the replication technology. Even though we see the two different technologies separately there are some high availability architecture where both can be used.