Task # your five (Individual)

Distribution 29 December 11

Objective: To Enhance Analytical Ability and Knowledge

2. Analyses and Compare the Physical Storage Structures and types of accessible INDEX in the latest editions of: 1 ) Oracle

installment payments on your SQL Machine

3. DB2

4. MySQL

5. Teradata

First of all determine comparative structure.

Recommend one particular product intended for organizations of around 2000-4000 employees with sound thinking based on Physical Storage Structures

Introduction to Physical Storage Structures

One attribute of an RDBMS is the freedom of reasonable data constructions such asВ tables, В views, andВ indexesВ from physical storage structures. Because physical and logical buildings are individual, you can control physical storage area of data without affecting entry to logical buildings. For example , renaming a repository file would not rename the tables trapped in it. The next sections clarify the physical database constructions of an Oracle database, including datafiles, remodel log files, and control files. Datafiles

Every single Oracle data source has more than one physicalВ datafiles. The datafiles include all the database data. The info of logical database constructions, such as desks and crawls, is physically stored in the datafiles given for a database. The characteristics of datafiles will be:

5. A datafile can be associated with only one data source.

5. Datafiles can easily have certain characteristics started let them automatically extend when the database runs out of space. 5. One or more datafiles form may well unit of database storage called a tablespace. Data within a datafile can be read, because needed, during normal databases operation and stored in the memory eclipse of Oracle. For example , imagine a user desires to access some data within a table of any database. In the event the requested info is not already inside the memory eclipse for the database, then it is read from the ideal datafiles and stored in memory. Modified or new info is not necessarily written into a datafile instantly. To reduce how much disk access and to enhance performance, data is put in memory space and drafted to the appropriate datafiles all at one time, as dependant on theВ database writer process (DBWn)В background process. Control Files

Just about every Oracle repository has aВ control file. A control file contains entries that designate the physical structure in the database. For instance , it contains this information: 2. Database brand

* Labels and spots of datafiles and update log files

5. Time stamp of data source creation

Oracle canВ multiplexВ the control file, that is, simultaneously maintain a number of the same control file copies, against a failure involving the control document. Every time anВ instanceВ of an Oracle database is definitely started, its control file identifies the database and redo logs that must be opened for data source operation to proceed. In case the physical make-up of the repository is modified, (for model, if a new datafile or redo log file is definitely created), then the control record is quickly modified by simply Oracle to reflect the change. A control file is also used in database restoration. Redo Log Files

Every Oracle database provides a set of two or moreВ redo log files. The set of remodel log files is collectively referred to as redo journal for the database. В A redo log is made up of redo entries (also calledВ redo records). The primary function of the redo log is usually to record almost all changes designed to data. When a failure stops modified data from staying permanently written to the datafiles, then the changes can be obtained through the redo log, so function is never lost. To protect against a failure involving the redo log alone, Oracle allows aВ multiplexed update logВ so that two or more clones of the update log could be maintained in different disks. The information within a redo log file can be used only to retrieve the repository from a system or mass media failure that prevents databases data by being crafted to the datafiles. For example , in the event that an unexpected power outage terminates database...

Recommendations: for Teradata