oracle database services handouts

7/31/2019 Oracle Database Services Handouts

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Managing Oracle

Database Workloadswith Services

Pete Dinin

NEOOUG Training Seminar

May 22, 2009


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Overview

Definitions and background

Creating and managing database services

Applications of database services


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Definition Database Services

First introduced in Oracle 8i.

Services are logical abstractions formanaging workloads.

Services divide workloads into mutuallydisjoint groupings.

Each service represents a workload with

common attributes, service-level thresholds,and priorities.


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Tnsnames Examples Connect to Instance:TEST_INSTANCE =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = testhost)(PORT = 1521))

)

(CONNECT_DATA =

(SID = test))

)

Connect to Service:TEST_SERVICE =

(DESCRIPTION =

(ADDRESS_LIST =

(ADDRESS = (PROTOCOL = TCP)(HOST = testhost)(PORT = 1521)))

(CONNECT_DATA =(SERVICE_NAME = test_service)

)

)


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Listener Registration

Each instance of database service registers with

listeners defined in local_listener and remote_listenerinit.ora parameters.

When a connection request is processed by the listener,it knows where the service is running, and will pass the

connection to the appropriate instance.

If the listener does not know of any instances where theservice is running, an error is returned.


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Creating Services

Without CRSdbms_service.create_service

service_names init.ora parameter

With CRSsrvctl add service

Grid Control Database > Maintenance >Cluster Managed Database Services

dbms_service.modify_service for additionalservice parameters (failover properties)


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Managing Services Single Instance

Starting & Stopping

dbms_service.start_service

dbms_service.stop_service

alter system set service_names='';

Automatic startup

Set service_names init.ora parameter to list of all services to bestarted at instance startup.

Create a startup trigger with logic to determine which services tostart using dbms_service.start_service.


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Managing Services - RAC Starting and Stopping

srvctl start/stop service

Grid Control Database > Maintenance > Cluster ManagedDatabase Services

CRS can automatically start services after databasesstart.

Modifying RAC servicessrvctl modify service

Grid Control Database > Maintenance > Cluster Managed

Database Servicesdbms_service.modify_service can configure failovercharacteristics of a service


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Default Services

SYS$USERS is the service assigned to a connectionmade without specifying a service name, such asbequeath or by instance name.

SYS$BACKGROUND is assigned to databasebackground processes.

RAC Default Service (dbname.domain) is created for allRAC Databases, and runs on all running instances.

Default services cannot be managed by the DBA.


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Implementation Tips Define a service for all applications. Do not include instance name in connect strings. If you

must connect to a specific RAC instance, create aservice for it.

Avoid bequeath connections. With RAC, avoid connections using the

dbname.domain default service, since manageability islimited.

Maximum number of services varies by version

10gR1: 64 services (including defaults)10gR2 and 11gR1: 118 services (including defaults)

Certain database features, such as DataPump andStreams, use services as well.


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Applications of Services

The following slides are examples of howDatabase Services can be used in thedatabase infrastructure.

Each example requires database services tohave been configured to gain the mostbenefit.


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Connection Control Control access to the database at the service

level. Some examples:

Stop a service used by an application middle-tier while upgrading an application.

Stop ad-hoc query users from connectingduring batch processing windows.

Normally a stop command only stops newconnections.

Using dbms_service.disconnect_session orsrvctl stop service (with the -f flag), existingconnections to that service can be killed aswell.


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SQL Tracing a Service

SQL Tracing can be enabled at the service level.

Ideal if you have an application with connection pooling,where you do not know which session contains the codeyou want to trace.

dbms_monitor.serv_mod_act_trace_enable

('service_name');

dbms_monitor.serv_mod_act_trace_disable

('service_name');


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Performance Views by Service

Available for sql queries:Service_name column in v$session

Service-level performance views which contain the same data asthe corresponding system and session views.

v$service_event

v$service_wait_class

v$service_stats

v$active_session_history contains a column service_hash, whichcan be joined to the name_hash column of dba_services to getthe service_name.

Service-level views are also presented in Grid Controlunder Instance Performance > Top Consumers


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System Utilization by App When multiple applications share a database, what

percentage of the workload belongs to each application? If each application has a service, you can use any

service-level metric.

Sample using DB CPU and ignoring SYS services:SELECT service_name,TRUNC (RATIO_TO_REPORT (SUM (VALUE)) OVER (), 4) * 100 percentage

FROM gv$service_stats

WHERE stat_name = 'DB CPU' AND service_name NOT LIKE 'SYS%'

GROUP BY service_name

ORDER BY 2 DESC;

This can be used for TCO calculations as well.


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11g Scheduler

With the 11g Oracle Scheduler, job classescan be defined for jobs.

Job classes can be defined with a service

name.

This will cause the jobs in that job class torun on the specified database service.


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Database Resource Manager

The Database Resource Manager allowspriority to be given to user processes basedon consumer groups.

Consumer groups can be defined based onvarious client attributes, including servicename.

This could allow certain services to have ahigher priority in the database than others.


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DataGuard DataGuard enables failover to standby database. But how do

clients find the new database location ?

Primary Database ConfigurationLocal listener references local machine

Remote listener references standby machine

Service initially started

Standby Database ConfigurationLocal listener references standby machine

Remote listener references primary machine

Service initially stopped

Tnsnames entry for service references both listeners. Client-side load balancing (load_balance=yes) is optional, however

is shown in the following example.


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Moving an Application An application needs to be moved from one shared

database to another. Assumes that tnsnames or othercentralized naming is used.

Move all underlying schemas and database objects to the newdatabase.

Create and start the service on new database.

Edit the tnsnames entry for the service to direct to the newlistener (if necessary).

There is no need to change any connection strings in the

application tier. To avoid tnsnames changes altogether, the old listener

redirect connections to the new database usingtechniques described for DataGuard.


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RAC Parallel Slaves 11g

10g Parallel slaves are managed withparallel_instance_group and instance_groupparameters.

11gParallel slaves have service affinity.Parallel slaves will be spawned on instanceswhere the parent sessions service is apreferred instance.

Note that the parallel_instance_group andinstance_group parameters are deprecated in11g as well.


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