Oracle data file structure

Oracle data file structure

Oracle 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

 

One tablespace can have multiple datafiles, and one datafiles can belong to only one tablespace.

For segement, you can remove the datafiles file, but for extent and blocks, it must be on a datafiles file.

Oracle's main data files include: parameter files spfile, password files orapwd, and data files datafiles online redo log files control files archive log files

Communication between the datafile data file and the instance's db buffer cache through the dbw0 Process

The redo log file communicates with the redo log buffer cache of the instance through lgwr.

There are usually several groups of redo log files, when a file is full, the next redo log file will be written. If all the redo log files are full, the data in the first redo log file will be overwritten from the beginning.

There are usually three groups of control files. If one file is corrupted, the damaged file will be repaired through the other two control files and the database will be started, we recommend that you store three groups of control files to different disk blocks. When the database is started, oracle reads the relevant indicators in the control file to complete database Initialization Configuration and start the oracle database instance.