m odule 3: w eek 6 d atabase management 1 itec 450 fall 2012
TRANSCRIPT
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MODULE 3: WEEK 6DATABASE MANAGEMENT
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ACCESS DATABASE – SQL PLUS
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SQL PLUS LOGIN
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SQL PLUS COMMANDS
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OEM (HTTPS://{HOSTNAME}:1158/EM)
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0THE 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 DICTIONARY
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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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0USEFUL 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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DRIVERS FOR CHANGE MANAGEMENT
Change 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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CHANGE 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 CHANGES
Data 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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EXECUTION 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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EXAMPLES OF DATABASE CHANGES
Change 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 AVAILABILITY
Availability 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 TECHNOLOGY
A cluster is a group of interconnected servers for increasing the reliability of servers.
Oracle standby database:
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0ORACLE REPLICATION
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SQL SERVER DATABASE MIRRORING
Database 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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ORACLE 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 TECHNOLOGY
RAID 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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