DB II
All of us are familiar with the term data. In fact, unknowingly we come across data in our day-to-day life everyday. The age of a person, price of potato, number of students in a school, pin code of a city, etc. are some examples of data. In our life we have to remember so much of data. But it is easier for us to remember all information for a few individuals. For example, you may be in a position to tell accurately the age, height, complexion, income, educational qualification, residential address, etc. of your close friends. But it is too difficult for you to memorise all these information for a large number of individuals. Let us consider the example of National Open School (NOS). Every year about one lakh students take admission in NOS. If you are asked to memorise records of date of birth, subjects offered and postal address of all these students, it will not be possible for you.
To deal with such problems we construct a database. We arrange all information about students in a tabular form. We keep all the records so that if I am asked, ‘How many students are there in Economics?’ I am in a position to answer.
Returning to those early days of personal computers, the arrival of Ashton-Tate's dBASE II was the event that heralded a relational database and commercial business processing environment on a personal computer. dBASE II had all the elements needed to generate a business application based on relational database principles.
It had a database engine, that element of software which manages the reading and writing of database tables to disk, in this case with the database definition embedded in the database itself; also DDL, a data definition language which is used to define and create the tables and their related indexes and keys,and it had DML, a data manipulation language that enabled the data to be manipulated, analysed and calculated- a true high-level language with easy-to-use screen I/O (input-output) for interaction with the users of the application.
DB2 is a family of relational database management system (RDBMS) products from IBM that serve a number of different operating system platforms. According to IBM, DB2 leads in terms of database market share and performance. Although DB2 products are offered for Unix-based systems and personal computer operating systems, DB2 trails Oracle's database products in UNIX-based systems and Microsoft's Access in Windows systems.
A relational database management system (RDBMS) is a program that lets you create, update, and administer a relational database. Most commercial RDBMS's use the Structured Query Language (SQL) to access the database, although SQL was invented after the development of the relational model and is not necessary for its use.
The leading RDBMS products are Oracle, IBM's DB2 and Microsoft's SQL Server. Despite repeated challenges by competing technologies, as well as the claim by some experts that no current RDBMS has fully implemented relational principles, the majority of new corporate databases are still being created and managed with an RDBMS.
An operating system (sometimes abbreviated as "OS") is the program that, after being initially loaded into the computer by a boot program, manages all the other programs in a computer. The other programs are called applications or application programs. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface such as a command language or a graphical user interface (GUI).
An operating system performs these services for applications:
* In a multitasking operating system where multiple programs can be running at the same time, the operating system determines which applications should run in what order and how much time should be allowed for each application before giving another application a turn.
* It manages the sharing of internal memory among multiple applications.
* It handles input and output to and from attached hardware devices, such as hard disks, printers, and dial-up ports.
* It sends messages to each application or interactive user (or to a system operator) about the status of operation and any errors that may have occurred.
* It can offload the management of what are called batch jobs (for example, printing) so that the initiating application is freed from this work.
* On computers that can provide parallel processing, an operating system can manage how to divide the program so that it runs on more than one processor at a time.
IBM's DB2 database software is the worldwide market share leader in the industry and marks the next stage in the evolution of the relational database. It is the industry's first multimedia, Web-ready relational database management system delivering leading capabilities in reliability, performance, and scalability with less skill and fewer resources. DB2 is built on open standards for ease of access and sharing of information and is the database of choice for customers and partners developing and deploying critical solutions. There are more than 60 million DB2 users from 400,000 companies worldwide relying on IBM DB2 Information Management technology.
applications and tools:
Products
DB2 Universal Database V8.1
IBM's relational database management system for AIX, Linux, HP-UX, Sun, and Windows.
DB2 Everyplace
DB2 relational database and enterprise synchronization architecture for mobile and embedded devices.
DB2 Universal Database for pSeries
delivers maximum range of capabilities for both hardware and software because of tight integration and joint engineering.
DB2 Universal Database for z/OS and OS/390
Use DB2 on the mainframe to run powerful enterprise applications, and make e-commerce a reality.
DB2 Server for VSE & VM
A full-function RDBMS supporting production and interactive VM and VSE environments for your company
Difference between db2 and informix
db2as is DB2 ADMINISTRATION SERVER, it is maily used to enable remote administration
of DB2 servers. For example, if your db2 server is on linux, you have a windows which
you installed db2 admin client, you want it to admin the db2 server on linux, then on
linux, you can login as db2as, then run $db2admin start
You should login as db2inst1 (During the installation, if you didn't change the
default name for db2 instance) to run the above commands.
db2 log manager is very different with informix's,
db2 has no physical log, each db has its own log, but informix share log within the
db server; During the crash recovery, db2 has no phyical and logical recovery phase;
On unix, the processing model is very different, db2 use agent, coordinator agent,
logical agent, ... Infomix use virtual processor concept; The optimizer level in is
from 1 to 9, I remembered in informix it is only 3 levels;
db2 has no dbspace. Informix store almost all the configuration information in
dbspace where user tables reside, db2 will store some of them in some files, separate
from user's data. db2 tablespace have two types: DMS, SMS. The structure for lob
space is very different. Informix's BLOB space structure is more complex. db2
configuration parameters (dbm cfg, db cfg, db2 registration and environment
variables) are far more than Informix's.
difference between db2 and oracle
DB2 offers
1. lower upfront licensing costs
2. easier upgrades and migrations (more stable api)
3. lower total cost of ownership (mostly driven by ratio of dba's to applications)
4. better price performance
5. a better thought out product (developer APIs and administration is more
intuitive - see 3)
6. superior business intelligence (datamart/datawarehouse) platform
DB2 is looking more like Oracle everyday, so there will be plenty of work for
performance engineers in the future.
DB2 was an OLTP database. IMS still runs rings around it.
The problem is that Oracle runs on servers that can be dedicated to Oracle
applications. When applications begin to bog down, then you start to replicate
databases, buy more servers, build network infrastructure, etc., etc.
DB2 is designed from the IBM model of "One Corporate Database". It is not going to
perform well with replication, BLOBs, 256-byte column names, etc. Foreign Keys (ie.,
"relational") are enough to degrade OLTP to tears.
Just throw processor and DASD at it (and money), or design systems to process data,
instead of pretty color pictures.
1. DB2 is cheaper than Oracle
2. If you want to do a lot of development using sql then Oracle is your choice.
3. If partitioning of data is a criteria especially in Data Warehouse choose Oracle
(it supports hash,range,list,composite) . DB2 support only hash paritionning. and
you need to have DB2 EEE verion of software.
Ainna Mae B. Rivera
CS 3-1
010067
