lecture about oracle and defination.pptx

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1. Lecture 1 : Oracle Database Architecture 1

2. Agenda 2 □ definition What is oracle database server? Oracle database server Architecture ‌ Background process

3. Defination 3 General defination . Collection of organized data is called database oracle definition: Instance+storage files is called oracle database

4. What is oracle database server? 4 □

5. Oracle database server Architecture 5 Enayatullah Naeemi java programming

6. Checkpoint process 6 Role : The Checkpoint process signals the DBWn (Database Writer) to write all dirty buffers to disk and update the datafile and control file headers with the checkpoint information. Purpose : Helps in reducing the time required for instance recovery by ensuring that all changes to data blocks are regularly written to disk.

7. SMON (system Monitor ( 7 Role : The System Monitor process performs instance recovery at startup if necessary. It also cleans up temporary segments that are no longer in use. Purpose : Ensures that the database is consistent and operational by recovering transactions that were active before a crash and by cleaning up temporary space

8. PMON ( Process Monitor ( 8 Role : The Process Monitor process performs process recovery when a user process fails. It cleans up the cache and frees resources that the process was using. Purpose : Ensures that the database resources are properly released and made available for other processes after a failure.

9. DBWR (Database Writer) 9 Role : The Database Writer process writes modified (dirty) buffers in the database buffer cache to the data files. There can be multiple DBWR processes Purpose : Ensures that changes made to data blocks in memory are eventually written to disk, thus making them permanent.

10. LGWR (Log Writer) 10 Role : The Log Writer process writes redo log entries from the redo log buffer to the online redo log files on disk. This is crucial for the recovery of transactions in case of a failure. Purpose : Ensures that all changes made to the database are recorded in the redo logs, which are essential for data recovery.

11. RECO ( Recoverer ) 11 Role : The Recoverer process resolves distributed transactions that are pending due to a network or system failure in a distributed database configuration. Purpose : Ensures that distributed transactions are either committed or rolled back, maintaining data consistency across multiple databases.

12. ARCR (Archiver) 12 Role : The Archiver process copies online redo log files to an archive location when they are full or when a log switch occurs. Purpose : Ensures that redo logs are archived for backup and recovery purposes, allowing for point-in-time recovery and the ability to recover from media failures.

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