Brown Bag Session 1

8/8/2019 Brown Bag Session 1

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BrownBrown BagBag Session #1Session #1


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sperrorlogsperrorlog


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sperrorlogsperrorlog

y A step further:

DBA can possibly set up a single table for all

users SQL*PLUS session audit?


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New memory parametersNew memory parameters


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y Prior to Oracle 11g, the DBA set the sga_targetand sga_max_size parameters, allowing Oracleto reallocate RAM within the SGA.

y The PGA was independent, as governed by thepga_aggregate_target parameter.


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y In Oracle 11g, the automatic memory management feature isdeveloped. Both SGA and PGA will expand and shrink based on the

instance demands.

y To enable this feature, set the following new parameters:

MEMORY_TARGET sets the system-wide usablememory that will be used by theinstance for SGA and PGA.

MEMORY_MAX_TARGET

(optional)

sets the maximum value you can

set for MEMORY_TARGETparameter.


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DRCPDRCP

Up until the Oracle 11g release, you could

use two ways to connect user sessions:

dedicated server process

shared server process


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DedicatedDedicated


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SharedShared


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Shared Server AnalogyShared Server Analogy


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DRCP in 11gDRCP in 11g


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DRCPDRCPy Consider an application in which the memory required

for each session is 400 KB and the memory requiredfor each server process is 4 MB.The pool size is 100and the number of shared servers used is 100.

y If there are 5000 client connections, the memory usedby each configuration is as follows:

y Dedicated ServerMemory used = 5000 X (400 KB + 4 MB) = 22 GB

y Shared ServerMemory used = 5000 X 400 KB + 100 X 4 MB = 2.5

GBy Database Resident Connection Pooling

Memory used = 100 X (400 KB + 4 MB) + 5000x35KB= 615 MB


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Dedicated Servers Shared Servers

Database Resident Connection

Pooling

When a client request is received, a

new server process and a session are

created for the client.

When the first request is received from

a client, the Dispatcher process places

this request on a common queue. The

request is picked up by an available

shared server process. The Dispatcher

process then manages the

communication between the client and

the shared server process.

When the first request is received from

a client, the Connection Broker picks an

available pooled server and hands off

the client connection to the pooled

server.

If no pooled servers are available, the

Connection Broker creates one. If the

pool has reached its maximum size, the

client request is placed on the wait

queue until a pooled server is available.

Releasing database resources involves

terminating the session and server

process.


terminating the session.


releasing the pooled server to the pool.

Memory requirement is proportional to

the number of server processes andsessions. There is one server and one

session for each client.


the sum of the shared servers andsessions. There is one session for

each client.


the number of pooled servers and theirsessions. There is one session for

each pooled server.

Session memory is allocated from the

PGA.


SGA.


PGA.


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Thank you.Thank you.

Now I have tossed a brick, hopefully will

attract a piece of gold .

Documents

Brown Bag Session 1