Advanced Oracle

8/11/2019 Advanced Oracle

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Opera Global Technical Services

Oracle

Architectural

Components




Architectural Components

There are several files, processes and memorystructures in an Oracle Server. Some of them areused when processing a SQL statement (ormanipulating an application like Opera).

Others are used to improve the performance of the

database, ensure that the database can be recoveredin the event of a software or hardware error, orperform other tasks necessary to maintain thedatabase.

The Oracle server consists of:

Oracle InstanceOracle database




Oracle Server




Oracle instance

A combination of background processes and memorystructures that access an Oracle database

Instance must be started before accessing thedatabase

Every time started, a System Global Area (SGA) isallocated and Oracle background processes arestarted

Background processes perform functions on behalf ofthe invoking process

They consolidate functions that would otherwise behandled by multiple Oracle programs running foreach user

Always opens one and only one database






Oracle Database

The physical structure consists of 3 file types + otherfile structures




Overview of Primary Components

System Global Area (SGA) Shared Pool

Library Cache

Data Dictionary Cache

Database Buffer Cache Redo Log Buffer Cache

Large Pool

Java Pool

Background Processes DBWn, PMON, CKPT, LGWR, SMON

Program Global Area (PGA)







Oracle

Storage

Structures




Physical vs. Logical




Datafiles

A datafile is a physical structure Can hold data for only one tablespace

Can resize dynamically

Space allocated upon creation

Opera database datafiles:System01.dbf, sysaux01.dbf, tempseg01.dbf,

undotbs01.dbf, findata01.dbf, finindx01.dbf,logdata01.dbf, logindx01.dbf, namedata01.dbf,

nameindx01.dbf, opera_data01.dbf,opera_indx01.dbf, oxi_data01.dbf, oxi_indx01.dbf,quickdata01.dbf, quickindx01.dbf, ratedata01.dbf,rateindx01.dbf, resvdata01.dbf, resvindx01.dbf,tools01.dbf




Tablespaces

Largest logical unit

Can reside in one or more datafiles

May contain one or more segments

Can be taken offline

Can be made readonly (SYSREAD)

OPERA database tablespaces:

system, sysaux, tempseg, undotbs, findata,

finindx, logdata, logindx, namedata, nameindx,opera_data, opera_indx, oxi_data, oxi_indx,quickdata, quickindx, ratedata, rateindx, resvdata,resvindx, tools




Logical Overview

SEGMENTS Second largest logical unit Can belong to only one tablespace, but can reside in

multiple datafiles Is made up of one or more extents

EXTENTS Third largest logical unit Can belong to only one segment and cannot spawn datafiles Is made up of contiguous Oracle BlocksWhen segments grow, new extents are added

BLOCKS Smallest logical unit Can belong to only one extent Corresponds to one or more operating system blocks DB_BLOCK_SIZE=8m in OPERA




Storage

Structures

In Depth




Storage Relationships




Types of Segments




Storage Clause Precedence




Extent Allocation/Deallocation




Block Contents

Header Top of the block

Data block address

Table directory

Row directory

Transaction slots

Free Space Middle of the block

Data

Bottom of the block




Automatic Space Management

Automatic segment-space management can only beenabled at the tablespace level for locally managedtablespaces:

CREATE TABLESPACE "OPERA_DATA" LOGGING DATAFILE'G:\oracle\oradata\QA10\OPERA_DATA01.dbf' SIZE 512M AUTOEXTEND ON NEXT 100M MAXSIZE 4096M,'G:\oracle\oradata\QA10\OPERA_DATA02.dbf' SIZE 5M AUTOEXTEND ON NEXT 100M MAXSIZE 4096M EXTENT

MANAGEMENT LOCAL UNIFORM SIZE 1M SEGMENT SPACEMANAGEMENT AUTO ;




Storage Information

Information about storage can be obtained byquerying the following:

DBA_EXTENTS

DBA_SEGMENTS

DBA_DATA_FILES

DBA_FREE_SPACE




UNDO

Management




Managing UNDO Data

Automatic:Introduced in 9i

Uses undo segments

System rollback segment

Cannot store any other objects

Extents are locally managed

Manual:Only option for 8i

Uses rollback segments




Managing UNDO Data




Read Consistency




Transaction Rollback




Automatic UNDO Management

Configure parameters in the initialization file:

####################################### System Managed Undo and Rollback Segments######################################

undo_management=AUTOundo_tablespace_UNDOTBS1undo_retention=3600

Create at least one Undo tablespace

SYSTEM: Used in the SYSTEM tablespace Non-SYSTEM: Used by other tablespaces Auto: Uses UNDO tablespaceManual: Uses Rollback Segments




UNDO Tablespaces

Only one Undo tablespace can be assigned to adatabase at a time

Can have more than one undo tablespace, but onlyone tablespace will be active

Switch active undo tablespace using the followingcommand: ALTER SYSTEM SET UNDO_TABLESPACE=undotbs2;

RAC databases have one undo tablespace per

instance




UNDO Information

Information about undo segments can beobtained by querying the following:

DBA_ROLLBACK_SEGS V$ROLLNAME

V$ROLLSTAT

V$UNDOSTAT

V$TRANSACTION




Managing

Tables




Table Storage Options




Structure of a Row




Row Migration and Chaining




Creating Tables

CREATE TABLE employee(id NUMBER(8) NOT NULL, last_name VARCHAR2(30))TABLESPACE userdata;

CREATE TABLE emp AS SELECT * FROM

employee;




Creating Temporary Tables

Contain session private data held by the duration ofthe transaction or session

CREATE GLOBAL TEMPORARY TABLE test

ON COMMIT PRESERVE|DELETE ROWS AS SELECT * FROM name;




Moving Tables

Non-partitioned tables can be moved to anothertablespace with the following statement:

ALTER TABLE test MOVE TABLESPACE tools;

Useful for reorganizing and eliminating row migration




Truncating Tables

TRUNCATE TABLE test;

Deletes all rows

Truncate its indexes

Delete triggers are not firedNo undo is generated

A table referenced by a foreign key can not betruncated




Dropping Tables

DROP TABLE test CASCADE CONSTRAINTS;

Extents released

CASCADE CONSTRAINTS option must be used if thetable is being referenced by a foreign key




Dropping Columns

ALTER TABLE test DROP COLUMN commentsCASCADE CONSTRAINTS CHECKPOINT 1000;

All data from the column is removed

CHECKPOINT command can be used to minimizeundo usage (expressed in number of rows)




Drop Column, UNUSED option

ALTER TABLE test SET UNUSED COLUMN commentsCASCADE CONSTRAINTS;

Data is not removed

Column becomes „invisible‟ Unused columns can be dropped with the

following command:

ALTER TABLE test DROP UNUSED COLUMNcomments CHECKPOINT 1000;




Table Information

Information about tables can be obtained byquerying the following:

DBA_TABLES

DBA_OBJECTS

DBA_TAB_COLUMNS

DBA_TAB_COMMENTS

DBA_COL_COMMENTS




Managing

Indexes




Index Classifications

LogicalSingle column or concatenated

Unique or nonunique

Function-based

DomainPhysicalPartitioned or nonpartitioned

B-tree (normal or reverse key)

Bitmap




B-Tree Index




Bitmap Index




B-Tree vs. Bitmap




Creating Indexes

Balance query and DML operations Place in separate tablespace

Use uniform extent sizes

NOLOGGING option for large indexes

CREATE [BITMAP] INDEX index_name ONtable_name(column [ASC|DESC], [column…])[TABLESPACE tablespace_name] [NOSORT][storage_clause][LOGGING|NOLOGGING];




Managing Indexes

Moving the index to a new tablespace: ALTER INDEX index_name REBUILD TABLESPACE

tablespace_name;

Rebuilding an index online:

ALTER INDEX index_name REBUILD ONLINE; Reducing fragmentation:

ALTER INDEX index_name COALESCE;

Dropping an index:

DROP INDEX index_name;




Index Information

Information about indexes can be obtained byquerying the following:

DBA_INDEXES

DBA_IND_COLUMNS

DBA_IND_EXPRESSIONS




DataIntegrity




Data Integrity




Types of Constraints




Constraint States




EXCEPTIONS Table

Create the table running the utlexcpt1.sql script Enable the constraint:

ALTER TABLE table_name ENABLE VALIDATECONSTRAINT constraint_name EXCEPTIONS INTO

system.exceptions; Use a subquery to find the offending rows:

SELECT * FROM table_name WHERE ROWID IN(SELECT ROWID FROM exceptions);

Modify the data with DML and re-enable theconstraint




Constraint Checking

Constraints can be setup as immediate ordeferred

Deferred constraintsuseful when both

parent and child keysare entered at the sametime

ALTER SESSION SET

CONSTRAINTS to makeconstraints immediateor deferred




Foreign Key Guidelines




Constraint Information

Information about constraints can be obtained byquerying the following:

DBA_CONSTRAINTS

DBA_CONS_COLUMNS




DataDictionary




Redo Logs




Redo Logs

Record all changes made to data Provides a means to recover the database

Can be organized into groups (multiplexing)

Minimum of two groups required

d k




How Redo Logs Work

Written in a cyclic fashionWhen one group is full LGWR moves to the next

group

Log switch and checkpoint occurs

d f




Redo Log Information

Information about the redo logs can be obtained byquerying the following:

V$LOG

V$LOGFILE V$LOGHIST

V$BACKUP_REDOLOG

A hi d R d L




Archived Redo Logs

Filled online redo logs can be archived The two advantages are:

A backup of the datafiles + redo logs + archivelogs can be used to restore the database up to the

last committed transaction.The backup can be made online.

When running in ARCHIVELOG mode a redo log filecannot be overwritten until

Checkpoint has completedRedo Log has been archived

By default the database is created in NOARCHIVELOGmode

A hi P




Archive Parameters

Archiving uses the ARCn background process to writethe redo logs to archive

initOPERA.ora archive parameters:

#log_archive_dest_1 =

"location=D:\oracle\admin\opera\archivemandatory REOPEN=120"

#log_archive_format=ARC%S_%R.%T

E bl A hi i




Enable Archiving

Set initOPERA.ora archiving parametersMount the database in exclusive mode

D:\ >sqlplus “sys/opera10g as sysdba”

SQL>Startup mount exclusive

Set the database in ARCHIVELOG modeSQL>ALTER DATABASE ARCHIVELOG;

Startup the database

SQL>ALTER DATABASE OPEN;

Di bl A hi i




Disable Archiving

Remove initOPERA.ora archiving parametersMount the database in exclusive mode

D:\ >sqlplus “sys/opera10g as sysdba”

SQL>Startup mount exclusive

Set the database in NOARCHIVELOG modeSQL>ALTER DATABASE NOARCHIVELOG;

Startup the database

SQL>ALTER DATABASE OPEN;




Tablespaces

AndDatafiles

T bl d D t fil




Tablespaces and Datafiles

All objects in the database are stored logically inTABLESPACES and physically in DATAFILES

TABLESPACES:- Belong to only one Database- Consist of one or more Datafiles

- Are divided in Segments, Extents and Blocks DATAFILES

- Belong to only one Tablespace- Physical files on the operating system

L ll M d T bl




Locally Managed Tablespaces

Reduced contention on the data dictionary No undo data generation when space allocation or

deallocation occurs No coalescing required UNIFORM sized extents are more reusable

CREATE TABLESPACE opera_data DATAFILE „g:\oracle\oradata\opera\ opera_data01.dbf‟ SIZE512M AUTOEXTEND ON NEXT 100M MAXSIZE 2048MEXTENT MANAGEMENT LOCAL UNIFORM SIZE 1M

SEGMENT SPACE MANAGEMENT AUTO;

Di ti M d T bl




Dictionary Managed Tablespaces

Extents managed in the data dictionary Each segment may have a different storage clause

Coalescing required

CREATE TABLESPACE opera_data DATAFILE „g:\oracle\oradata\opera\ opera_data01.dbf‟ SIZE512M EXTENT MANAGEMENT DICTIONARY DEFAULTSTORAGE (initial 1M NEXT 1M PCTINCREASE 0);

T T bl




Temporary Tablespace

Used for sort operations Cannot store any permanent objects Locally managed extents Tempfiles are always NOLOGGING

CREATE TEMPORARY TABLESPACE tempseg TEMPFILE‘g:\oracle\oradata\opera\temp01.dbf’ SIZE 512MEXTENT MANAGEMENT LOCAL UNIFORM SIZE 4M;

Default temporary tablespace define at database creation. Can change the default temporary tablespace

ALTER DATABASE DEFAULT TEMPORARY TABLESPACEtempseg;

Cannot be taken offline or dropped until a new temporarytablespace is available

R d O l T bl




Read Only Tablespace

The following command makes a tablespace readonly:

ALTER TABLESPACE sys_read READ ONLY;

This causes a checkpoint

Data within the tablespace is available only forSelects

Objects can be dropped

SYS_READ tablespace

R i i T bl




Resizing Tablespaces

ALTER DATABASE ALTER TABLESPACE

Can change the size of a tablespace by:

Alter the size of the datafile

Alter the datafile to have AUTOEXTEND turned on

Add a datafile

ALTER DATABASE DATAFILE „g:\oracle\oradata\opera\ opera_data01.dbf‟ RESIZE 4096m;

ALTER DATABASE DATAFILE

„g:\oracle\oradata\opera\ opera_data01.dbf‟ AUTOEXTEND ONNEXT 100m MAXSIZE 4096m;

ALTER TABLESPACE opera_data ADD DATAFILE „g:\oracle\oradata\opera\ opera_data02.dbf‟ size 2048m;

Mo ing o Renaming Datafiles




Moving or Renaming Datafiles

Shutdown the database Physically on the OS move the datafile

Startup mount the database

Execute: ALTER DATABASE DATAFILE

„g:\oracle\oradata\opera\ opera_data01.dbf‟ TO „h:\oracle\oradata\ opera_data01.dbf‟;

Open the database

Tablespace Information




Tablespace Information

Information about tablespaces and datafiles can beobtained in the following views: TablespacesDBA_TABLESPACES V$TABLESPACE

DatafilesDBA_DATA_FILES V$DATAFILE

Temporary files

DBA_TEMP_FILES V$TEMPFILE




Networking

Oracle Net Services




Oracle Net Services

Oracle 9i/10g Standard




Oracle 9i/10g Standard

Oracle RAC Option




Oracle RAC Option

Oracle Net Models




Oracle Net Models

Locally Managed:Files reside on each computer

listener.ora (server)tnsnames.ora (client)sqlnet.ora (server and client)

Centrally Managed:LDAP directory server

ldap.ora (server and client)Oracle Names server

names.ora (server and client)

Opera Local Naming




Opera Local Naming

Establishing a Connection




Establishing a Connection

Default Listener Parameters




Default Listener Parameters

Listener Contents




Listener Contents

Listener contains the following entries:Listener‟s name

Protocol addresses that it is accepting connectionrequests on

Services it is listening forControl parameters

Dynamic Service Registration




Dynamic Service Registration

Initialization file contains the following entries:SERVICE_NAMES

INSTANCE_NAME

LOCAL_LISTENER for non-default listener

REMOTE_LISTENER for RAC

LSNRCTL Utility




LSNRCTL Utility

Listener Control Utility enables manupulation of thelistener through the command line

LSNRCTL> command_name LSNRCTL> help

The following operations are available

An asterisk (*) denotes a modifier or extended command:

start stop statusservices version reloadsave_config trace change_passwordquit exit set*

show*




Cost

BasedOptimizer

Query Optimization




Query Optimization

A query is a non-procedural request of informationfrom the database. To process a query the kernel hasto characterize the retrieval strategy or formulate anexecution plan for fetching the candidate rows.Typically, to execute a query, several execution plansmay be feasible. For example, tables participating in

a join could be processed in a number of differentorders depending on the join conditions and the joinmethods implemented in the kernel. To choosebetween alternative plans, the kernel must use somerealistic unit to measure the resources used by each

plan. It can then choose between competing plans onthe basis of costs and discard all except the onewhich consumes the least.

Cost Based Optimizer




Cost Based Optimizer

Oracle addresses query optimization by incorporatinga Cost Engine in the kernel to estimate and selectexecution plans on the basis of costs.

Costs quantify the resource consumption of thequery.

Resources used by a query can be broken into threeprincipal parts I/O cost

CPU Costs

Network Costs

Cost Based vs Rule Based




Cost Based vs. Rule Based

The RBO has a set number of rules that SQL uses tocreate an execution plan. For example: The RBOdesignates whether an index is used/not used orwhich table in the FROM clause should be theprimary table in a union. There are approximately 16

different rules from which the RBO can choose. The CBO operates very differently from the RBO.

CBO uses actual table statistics to determine the bestexecution plan. These statistics are gathered runningGather Schema Statistics.

Analyze Objects




Analyze Objects

To enable costing of execution plans, detailedstatistical descriptions of the data relating to objectsin the query is required. The statistics are generatedby the ANALYZE facility.

There are two modes in which analyze may be

performed COMPUTE

Compute scans each member of the object

ESTIMATEEstimate mode looks at a sample of the total.

If there are no statistics, then the cost optimizer useshardcoded estimates or "guesses".

Gather Statistics Command




Gather Statistics Command

executedbms_stats.gather_database_stats(options=>'GATHER',estimate_percent=>dbms_stats.auto_sample_size,method_opt=> 'FOR ALL COLUMNS SIZE AUTO',cascade=>true);

GATHER STATS JOB




GATHER_STATS_JOB

GATHER_STATS_JOB runs every night at midnight togather stale statistics

Verify the job by viewing the DBA_SCHEDULER_JOBSview:

SELECT * FROM DBA_SCHEDULER_JOBS WHERE JOB_NAME= 'GATHER_STATS_JOB';

Verify statistics in a schema are current by queryingLAST_ANALYZED column in dba_tables select distinct(last_analyzed), owner from dba_tables;




Daylight

SavingsTime

DST Changes




DST Changes

The Energy Policy Act of 2005 was signed into law in August 2005 to extend daylight saving time.

Beginning in 2007, daylight saving time in the U.S. willbegin on the second Sunday in March and end the firstSunday in November rather than beginning on the first

Sunday in April and ending the last Sunday in October, asit did in the past.

Under the new rules for 2007, DST will start on March 11,2007 end on November 04, 2007. As a result the database

may report incorrect time zone data between 03/11/2007 – 04/01/2007 and between 10/28/2007 – 11/04/2007 (andon different dates in subsequent years), unless therequired patches are applied.

What is the database timezone?




What is the database timezone?

The database time zone is not as important as it sounds. First ofall it does not influence functions like sysdate, or systimestamp.These function take their contents (date and time, and in thecase of systimestamp also time zone) completely from the OSwithout any "Oracle" intervention.

The only function of the database time zone is that it functionsas a time zone in which the values of the "TIMESTAMP WITHLOCAL TIME ZONE" (TSLTZ) datatype are normalized when theyare stored in the database.

However, these values are always converted into the sessiontime zone on insert and retrieval, so the actual setting of thedatabase time zone is more or less immaterial.

DST Patch




DST Patch

Who needs the DST patch?ONLY locations where the database is not in the

same time zone as the hotel would beaffected. Mostly larger sites will be impacted, like

Candlewood datacenter. All sites just need tomake sure they have the OS patches/updatesapplied.

The patch is applied to the database. It replaces twofiles and requires the database to be restarted.

The patch is included in the Micros 403 database CD.




OPERA_SMT

Opera SMT Command Line




Opera_SMT Command Line

SMT now supports command line Command Line Functionality:

COMPILE to compile a schema

EXPORT to export a schema

IMPORT to import a schema - (requires SYSpassword!)

EPATCH to run scripts against a schema

ANALYZE to analyze schema (Oracle 10g only) -

(requires SYS password!)

SMT Command Line Syntax




SMT Command Line Syntax

opera_smt /cmd=<command>[;<command options>]

<command> ::= ['COMPILE', 'EXPORT', 'IMPORT', 'SYNONYM','EPATCH', 'ANALYZE']

<command option> ::= <parameter>=<value>

<parameter> ::= ['USR','PWD','ODB','SYPWD','LOG','O9I','ZIP','TBS','OPU','OPP','OPD','OXU','OXP','OXD','SIL','SYN','DBG']

SMT Command Line Parameters




SMT Command Line Parameters

USR: Oracle UserName/SchemaName PWD: Oracle Schema/User Password ODP: Oracle Database Alias (as specified in TNSnames.ora) SYPWD: SYS password LOG: Log file name (always overwritten) O9I: <Y, N> Use 9i export utility (only for import into 9i database) ZIP: <Y, N> Create selfextracting Archive on export TBS: Tablespace for imported schema OPU: Opera Schema UserName (on Import if imported schema is

OXI/OXIHUB) OPP: Opera Schema Password (on Import if imported schema is

OXI/OXIHUB) OPD: Opera Schema Alias (on Import if imported schema is

OXI/OXIHUB) SIL: <Y, N> Silent mode, no output on command window DBG: <Y, N> Debug mode

SMT Command Line Examples




SMT Command Line Examples

Compile Opera Schema opera_smt

/cmd=compile;usr=opera;pwd=opera;odb=opera;log=smt_compile.log

Compile Opera Schema and refresh all synomyms opera_smt

/cmd=compile;usr=opera;pwd=opera;odb=opera;log=smt_compil

e.log;syn=y Export Opera Schema

opera_smt /cmd=export;usr=opera;pwd=opera;odb=opera;zip=n;log=smt_export.log /id:\export\opera\opera.dmp

Import Opera Schema

opera_smt /cmd=import;usr=newopera;pwd=newopera;odb=opera;sypwd=******;log=smt_import.log /id:\export\opera\opera.dmp




OPERAInformation

OPERA Commands




OPERA Commands

sqlplus opera/opera Select * from installed_app;

select license_code from installed_app_licenses;

ALTER USER user_name IDENTIFIED BY

new_password; DROP USER user_name [CASCADE];

OPERA File Locations




OPERA File Locations

alertOPERA.logG:\oracle\admin\opera\bdump

Arvhive logsD:\oracle\admin\opera\archive

Control FilesD:\oracle\oradata\opera\control01.ctlG:\oracle\oradata\opera\control02.ctl

OPERA datafiles:\oracle\oradata\opera\<datafile_name>.dbf

Character Set




Character Set

UTF8 Unicode Varying width multibyte US7ASCII characters (A-Z,a-Z,0-1 and ./?,*# etc..) are in

UTF8 1 byte, so for most West european languages theimpact is rather limited as only "special" characters like ç, ñ ,

é will use more bytes then in a 8 bit characterset.

Information about NLS settings can be obtained byquerying the following: NLS_DATABASE_PARAMETERS

NLS_INSTANCE_PARAMETERS NLS_SESSION_PARAMETERS V$NLS_VALID_VALUES




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