Oracle data file Structure

Oracle 's data structures are divided into physical and logical structures

Physical Structure: Data block of the operating system-> data file datafiles

Logical Structure: Minimum database block-->extent-->segement--> Tablespace-->databases

Where for a tablespace can have more than one datafiles, one datafiles can only belong to a Tablespace

For segement can no longer be on a datafiles file, but for extent and Blocks must be on top of a datafiles.

Oracle 's main data files are : parameter file spfile, password file orapwd file, data file Datafiles Online redo log files redo log files control Files Archive log Files

db buffer cache for datafile data files via dbw0 process with instance Complete Communication

For redo log file complete with instance redo log via LGWR Buffer cache Communication

For redo log file The general situation is that there are several groups, when a file is full, will then write down a redo log file if all the redo log file is full, the data from the first redo log file is overwritten from the beginning.

For control files , you will typically have three groups, and if one file is corrupted, the corrupted file will be repaired with the other two control files, and the database is started, and it is recommended that you store the three sets of control files to different disk blocks. When the database is started,oracle reads the relevant metrics in control file to complete the initialization of the database and start the Oracle  Database instance.

Oracle data file Structure