Oracle 9i Database Administration in 10 Minutes
CH1: Understanding the Oracle Environment | CH2: Understanding the Oracle Instance | CH3: Understanding the working of Oracle Instance | CH4: Understanding Oracle Database | CH5: Oracle 9i Software Installation | CH6: Oracle 9i Database Design using DBCA | CH7: Enabling Other Computers to Access Oracle Server | CH8: Oracle Enterprise Manger | CH9: Oracle Backup & Recovery -Simple Technique | CH10: Oracle Performance Tuning
Chapter 3: Understanding the working of Oracle Instance
The Shared Server mode can be best visualized if you imagine a restaurant as shown in the Figure 8. There are two waitresses serving more people. In this case the “idle time” for each waitress will be less compared to the situation where we will be having one waitress per person.
Figure 8: Restaurant Running Under Shared Waitress
Mode
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In Shared Server mode there is a dispatcher process, which receives the users request and places it in the “Request Queue”. Server process “when it’s free”’ picks up the request from the request queue, processes it and put the response back in response queue. Dispatcher process “when it’s free” picks up the response from the response queue and sends it to the specific user who submitted that request.
The point to be noted over here is that request and response queues are not processes. They are part of SGA or in other words part of memory (RAM) utilized by processes. In Dedicated Server mode there is neither Request/Response Queues nor any Dispatcher process. Whenever a user connects to Oracle Instance, one new Server process gets created to serve him/her.
Figure 9: Restaurant Running Under Dedicated Waiter
Mode
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Chapter 3: Understanding the working of Oracle Instance
CH1: Understanding the Oracle Environment | CH2: Understanding the Oracle Instance | CH3: Understanding the working of Oracle Instance | CH4: Understanding Oracle Database | CH5: Oracle 9i Software Installation | CH6: Oracle 9i Database Design using DBCA | CH7: Enabling Other Computers to Access Oracle Server | CH8: Oracle Enterprise Manger | CH9: Oracle Backup & Recovery -Simple Technique | CH10: Oracle Performance Tuning
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