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MODULE 3: WEEK 6DATABASE MANAGEMENT

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ACCESS DATABASE – SQL PLUSFall 2012

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SQL PLUS LOGINFall 2012

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SQL PLUS COMMANDSFall 2012

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OEM (HTTPS://{HOSTNAME}:1158/EM)

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ITEC 450THE DATA DICTIONARY

Looking at Data Dictionary Components Using Data Dictionary Views Useful Dynamic Performance Views Examining Table Structure Using SQL*Plus

and iSQL*Plus

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LOOKING AT DATA DICTIONARYFall 2012

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LOOKING AT DATA DICTIONARY Generally, USER, ALL, and DBA views are in sets

USER_TABLES, ALL_TABLES, DBA_TABLES Each view has nearly identical columns

USER version omits OWNER column; it also sometimes omits columns to simplify the view

V$ and GV$ views are in sets There are few views that don’t begin these prefixes For simplicity, all views (except DBA ones) prefix

public synonyms and public permission to query

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USING DATA DICTIONARY VIEWS Frequently used (static) data dictionary

views: USER_TABLES, USER_VIEWS ALL_DEPENDENCIES USER_ERRORS USER_INDEXES, USER_IND_COLUMNS DBA_SOURCE USER_TAB_PRIVS, ALL_TAB_PRIVS_MADE USER_TAB_PRIVS_MADE DBA_USERS PRODUCT_COMOPONET_VERSION

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ITEC 450USEFUL DYNAMIC PERFORMANCE

VIEWS Begin with V$ and have a counterpart GV$

view V$SYSSTAT V$SQL V$SESSTAT V$SESSION_WAIT V$FILESTAT V$FILESTAT

Primary use: tuning the database system Oracle provides options for gathering/viewing

stats Statistics are used to tune a database This book does not cover the details of DB tuning

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MODULE 3 DATABASE MANAGEMENTSection 1 Database Change Management

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ITEC 450DRIVERS FOR CHANGE MANAGEMENTChange is inevitable but necessary for

business survival and success. Missed a requirement – an existing system

is missing a feature Identified a defect Scalability demand, marketplace changes Policy and politics – process, procedure or

methodology; legislation changes

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ITEC 450CHANGE MANAGEMENT REQUIREMENTS Proactively change – the earlier to make

change, the lower cost to achieve it Planning analysis – intelligently examining

the change whether it is necessary, and planning to do it right the first time

Impact analysis – comprehensive impact and risk analysis

Execution – standardization of procedure, availability consideration, quick and efficient delivery

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TYPES OF DATABASE CHANGES DBMS software – versions and releases for

new features, functions, bug fixes, support models

Hardware configuration – memory, CPU, storage device

Logical and physical design for an application

Physical database structures

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IMPACT OF DATABASE CHANGESData Definition Language is mainly used for

database changes. Create, alter, and drop schema objects

require exclusive access to the specified object

The change is implicitly committed The change may cause dependent objects

become invalid, which may need to recompile or reauthorize schema objects

Recovery from a database change is challenging, and has to be well-planned.

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ITEC 450EXECUTION OF DATABASE CHANGES Maintain current database structures

– source control and version control Migration process

Request database change Standardized change requests Managing database changes from one

database environment to another Condense a series of changes by comparing

database structures, and migrate the differences

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ITEC 450EXAMPLES OF DATABASE CHANGESChange Management: planning (necessary?)

impacts, and execution (recovery?) Add a new column to the end of a table Resize a column from char (8) to char (12) Re-create a new package, procedure, or

function Add a new column to the middle of a table

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MODULE 3 DATABASE MANAGEMENTSection 2 High Availability Requirement and Architecture

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DRIVERS OF AVAILABILITYAvailability is the condition where a given

resource can be accessed by its consumers. Mandate for 24x7 availability Shrinking maintenance window Full-time availability: airline reservation

systems, credit card approval Cost of downtime

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AVAILABILITY PROBLEMS Disasters: loss of the data center System failures

Server infrastructure problems: network , loss of the server hardware, storage, operating system

Software failure: DBMS, application, corruption of data

Data failures Procedure problems: security and authorization,

loss of database objects Human errors: loss of data, DBA mistakes

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AVAILABILITY SOLUTIONS Automate DBA functions Exploit high-availability DBMS features Exploit clustering technology Hardware redundancy design

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HIGH AVAILABILITY DBMS FEATURES Solutions to disasters

Oracle data guard – a single primary database and one or more standby database

SQL Server database mirroring – a single copy of the mirrored database that must reside on a different server instance, usually on a separate physical server in a different location

Hardware replication: EMC SRDF Solutions to system failures

Oracle Real Application Clusters SQL Server transactional replication DB2 Data Sharing

Solutions to data failures Backup and recovery capability Flashback database: view data at a point-in-time in the past Partition: decompose large tables and indexes into smaller

and more manageable pieces

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CLUSTERING TECHNOLOGYA cluster is a group of interconnected servers

for increasing the reliability of servers.

Oracle standby database:

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ITEC 450ORACLE REPLICATION

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SQL SERVER DATABASE MIRRORINGDatabase mirroring

maintains an exact copy of the database on the mirror.

It works at the level of the physical log record (by sending the actual log records to the mirror server).

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SQL SERVER TRANSACTIONAL REPLICATION ARCHITECTURE

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ITEC 450ORACLE REAL APPLICATION CLUSTER (RAC)Oracle

database with RAC architecture build higher levels of availability on top of the standard Oracle features.

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HARDWARE REDUNDANCY DESIGN No single point of failures on CPU, Memory,

I/O controller, Network, etc. Clustered software to failover to another

server in seconds RAID technology (Redundant Arrays of

Inexpensive Disks) – one large logical storage unit with a set of physical disk drives

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RAID TECHNOLOGYRAID example

with 4 disks and striping.

Pages 1-4 can be read/written simultaneously

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WRAP UP Assignment 6-1: Research Paper: Database

High Availability

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