In this video, review the purpose of the Oracle SGA and define its role within the Oracle instance.
- [Instructor] Say hello to the Oracle Instance in all its glory. Beautiful, isn't it? Previously, when introducing the function of the Oracle Instance, we treated it as a single unit that serves the function of caching data and performing routine operations required for transactional processing via a set of background processes. But that is just scratching the surface. The Oracle Instance is actually more complex than that. And now is the time for us to pull back the curtain and take a peek inside.
The first part of the Oracle Instance you need to be familiar with is called the SGA, or system global area. It might seem a bit confusing, at first, but bear with me, as there is logic to the naming. The SGA is the first part of the Oracle Instance that is used to cache data and metadata in memory. The second part being the Oracle background processes, which we will talk about in our next chapter. The SGA is a group of shared memory structures, known as individual SGA components, which are used to cache user-generated data, that is, rows from data-based tables, as well as various other control information that the Oracle Instance requires.
The SGA is the name used to represent a collection of various caches in memory. The buffer cache, shared pool, and others are all components of a single SGA. While each of these individual caches serves its own unique purpose, luckily for us we don't have to manually size each of these components individually. When we configure the database, we will use a couple of parameters to determine the overall size of the SGA as a whole.
These parameters are SGA_MAX_SIZE and SGA_TARGET. We set a maximum size for the entire SGA, say 64 gigabytes, and it's up to Oracle to determine how much of the total SGA it should allocate for each individual memory component based on demand as well as memory availability. We can, of course, override the automatic sizing, if we prefer.
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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