Oracle Question - I
11) What is the use of the large Pool?
Large pool is mainly used to offload some burden of caching
from shared pool.
Large pool is a memory structure used during rman backup
with multiple channel location.
It is also used when DBWR I/O slaves are configured.
Finally most importantly it is used to store UGA(user global area) when database is configured in shared server configuration.
Without large pool being configured all these information would be stored in shared pool thereby
reducing the library hit ratio of shared pool and
degrading the performance
12) What is the use of java pool?
Java Pool is mainly used to load Java class and
libraries in oracle database
13) What is Dedicated Server Configuration?
In case of dedicated server configuration for each client which
tries to connect to the database
a user process is generated in the client machine and
when this client gets authenticated by the listener at the server,
the listener spawns a server process which fires the queries and fetches
the data from the database on behalf of the user process on the client.
Also this server process is dedicated to that particular client only and
serves only the request of that particular client
Hence such type of confirguration is called as
dedicated server process. The dedicated server configuration
requires more resources viz memory but provides better perfromance
14) What is Shared Server Configuration ?
In Shared Server Configuration when the client tries
to connect to database a user process is spawned at
the client machine.This client is authenticated by the listener on the
database server and handed over to the dispatcher.
There are normally few dispatcher pre spawned when the instance is started dependinding on the dispatchers
parameter in init<SID>.ora
The Dispatcher places the request from client to the
common request queue placed in the sga.
The idle shared server which are also pre spawned
will pick the request from request queue service
the request and place it in the response queue
which is dedicated to each dispatcher.
The Shared server configuration requires less resources
like memory scarely and is the
favourite configuration for internet application
where large users connect to database
15) Where is the Session Information stored in case of dedicated server configuration?
In case of the Dedicated server Configuration the session
information is stored in PGA.For each session which is established
a dedicated server process is spawned. And for each dedicated server process a memory structure called as PGA
(Program Global Area) is
allocated. This PGA memory is used to store bind variable information,
cursors and session information for that particular session.
16) Where is the Session Information stored in Shared Server Configuration?
In case of the Shared server Configuration the session information
is stored in Shared pool.
Because in shared server confirguration all the session are not linked
to same shared server during the entire period of the session.
17) Where is Shared Server Configuration used in Oracle Database?
The Shared Server is used in internet application
where large users connect to database.
It is also used in application where not all the users connect or
hit the database simultaneously
Shared server Confirguration is based on the concept that between
two consequent queries fired by a particular session on the database
there is a idle time for server process and this idle time is
used to serve request from other clients.
18) Which process starts the shared server process dynamically?
In shared server confirguration initially shared servers
specified by shared_server parameter in init<SID>.ora is started at instance startup.
But as the load on the shared server process
increases background process PMON starts the shared server process dynamically .
19) What is the maximum of number of shared servers which can be started by PMON?
The max number shared server processes which can be started by PMON is decided by
max_shared_servers parameter in init.ora