M ODULE 3: W EEK 6 D ATABASE MANAGEMENT 1 ITEC 450 Fall 2012

A CCESS D ATABASE – SQL P LUS Fall ITEC 450

SQL P LUS L OGIN Fall ITEC 450

SQL P LUS C OMMANDS Fall ITEC 450

OEM ( HTTPS ://{ HOSTNAME }:1158/ EM ) Fall ITEC 450

T HE D ATA D ICTIONARY Looking at Data Dictionary Components Using Data Dictionary Views Useful Dynamic Performance Views Examining Table Structure Using SQL*Plus and iSQL*Plus Fall ITEC 450

LOOKING AT DATA DICTIONARY Fall ITEC 450

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 Fall ITEC 450

U SING D ATA D ICTIONARY V IEWS 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 Fall ITEC 450

U SEFUL D YNAMIC P ERFORMANCE V IEWS Begin with V$ and have a counterpart GV$ view V$SYSSTAT V$SQL V$SESSTAT V$SESSION_WAIT 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 Fall ITEC 450

M ODULE 3 D ATABASE M ANAGEMENT Section 1 Database Change Management 11 ITEC 450 Fall 2012

D RIVERS FOR C HANGE M ANAGEMENT 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 Fall ITEC 450

C HANGE M ANAGEMENT R EQUIREMENTS 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 Fall ITEC 450

T YPES OF D ATABASE C HANGES 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 Fall ITEC 450

I MPACT OF D ATABASE C HANGES 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. Fall ITEC 450

E XECUTION OF D ATABASE C HANGES 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 Fall ITEC 450

E XAMPLES OF D ATABASE C HANGES 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 Fall ITEC 450

M ODULE 3 D ATABASE M ANAGEMENT Section 2 High Availability Requirement and Architecture 18 ITEC 450 Fall 2012

D RIVERS OF A VAILABILITY 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 Fall ITEC 450

A VAILABILITY P ROBLEMS 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 Fall ITEC 450

A VAILABILITY S OLUTIONS Automate DBA functions Exploit high-availability DBMS features Exploit clustering technology Hardware redundancy design Fall ITEC 450

H IGH A VAILABILITY DBMS F EATURES 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 Fall ITEC 450

C LUSTERING T ECHNOLOGY A cluster is a group of interconnected servers for increasing the reliability of servers. Oracle standby database: Fall ITEC 450

ORACLE REPLICATION Fall ITEC 450

SQL S ERVER D ATABASE M IRRORING 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). Fall ITEC 450

SQL S ERVER T RANSACTIONAL R EPLICATION A RCHITECTURE Fall ITEC 450

O RACLE R EAL A PPLICATION C LUSTER (RAC) Oracle database with RAC architecture build higher levels of availability on top of the standard Oracle features. Fall ITEC 450

H ARDWARE R EDUNDANCY D ESIGN 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 Fall ITEC 450

RAID T ECHNOLOGY RAID example with 4 disks and striping. Pages 1-4 can be read/written simultaneously Fall ITEC 450

W RAP U P Assignment 6-1: Research Paper: Database High Availability Fall ITEC 450