the phycial structures of the database are 1.datafile2.redologfile3.control filedatafile:- datafile contains actial data of the database.redologfile:- it contains all changes done to the data base.it works in the circular fashion.controlfile:- it contains status and structure of the database.
Data files -- always occupy the declared size on the hard disk irrespective of the rows contained in them (.dbf). The data files contain
Data blocks -- smallest unit of I/O. each block contains a header
ROWID -- two byte pseudo column to identify phsical location of a row
Table clusters -- tables which are often used together in queries are physically grouped in same data block. Cluster tables are joined on 'cluster key' which identifies the common column between the two tables.
Online redo log files (.rdo and .arc)
Control files -- contain one slot per data file declared for a database. Also contain other configuration parameters. (.ctl)
mainly consist of 3 files1) control file2)redolog file3)data filecontrol file-contain current status of the datafiles , redolog file. contain location of datafile and control file.redolog file- records all the changes made to the database.log writer writes the redo enries from the redolog buffer to the redolog file.datafile-
Get invaluable Interview and Career Tips delivered directly to your inbox. Get your news alert set up today, Once you confirm your Email subscription, you will be able to download Job Inteview Questions Ebook . Please contact me if you there is any issue with the download.