In this video, we will describe the concept of database checkpoint and how the CKPT process maintains checkpoints and thus expedidates the process of database recovery
- [Instructor] The next background process in our list is the checkpoint process, or CKPT in short. This process handles database checkpoints. We discussed database checkpoints briefly when we talked about the database writer background process, but let's do a quick recap. An Oracle checkpoint is a database event which synchronizes modified data blocks in memory from the buffer cache with the data files on disk. It is an event that happens regularly when the Oracle database declares a state of internal consistency, internal consistency between modifications which have been done in memory and the data that has been written to disk.
A checkpoint has two purposes. One is to establish data consistency between memory and disk, and the other is to enable a faster database recovery process. Checkpoints are a crucial element in database recovery. The more database blocks we have which have been modified in memory but also have been written to disk, the less we have to rely on the redo logs for recovery. When a checkpoint occurs, the oracle database must update the headers of all data files to record that the new checkpoint has indeed occurred.
This is done by the background process called CKPT. Each database checkpoint generates a unique sequential identifier known as the SCN or system change number. This sequential number is recorded by the CKPT process in the database file headers. Note that the CKPT process does not write the actual data blocks from memory to disk. That's what the database writer is for. The SCN is recorded in both the Oracle data files which, well, contain the actual data of our database, as well as in a special set of files known as the Oracle control files.
Every Oracle database has a control file, which is a small binary file that records the physical structure of the database. By physical structure, I mean that the control file keeps track of the location, that is, name or path of certain files in the Oracle storage, not the names of tables or columns. That's a logical structure. We will talk more about control files in our next chapter.
After completing this course, you'll have fundamentals required for installation, configuration, and administration of an Oracle 12c database.
- Database instance and storage
- Instance memory pools
- Instance background processes
- Client connections
- Database storage file types
- Control files and backup files
- Multitenant databases
- Starting and stopping the database
- Installing Oracle 12c software
- Using the developer tools
- Database management
Skill Level Beginner
Database Foundations: Core Conceptswith Adam Wilbert2h 14m Beginner
Database Foundations: Administrationwith Adam Wilbert1h 14m Beginner
Learning Relational Databases (2014)with Adam Wilbert2h 39m Beginner
2. Instance Memory Pools
3. Instance Background Processes
4. Client Connections
5. Physical Database Structures
6. Mulitenant Database
7. Start and Stop the Database
8. Install Oracle 12c software
9. Create a Database Instance
Use DBCA to create a database14m 55s
10. Tools for Developers and DBAs
Next steps1m 17s
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