Steve GeorgeSr. Delivery ManagerOracle University Oracle Corporation

Tips, tricks and Techniques for the Oracle Database

Overview

This course concentrates on Oracle9i Release 2 new features applicable to database administration

Previous experience with Oracle databases is required for a full understanding of many new features, particularly Oracle8 and Oracle8i

Displaying Execution PlansSQL*Plus Autotrace

• Create the plan_table table.• Create and grant the plustrace role.

•

• Autotrace syntax:

SQL> @$ORACLE_HOME/sqlplus/admin/plustrce.sql

SQL> GRANT plustrace TO scott;

SET AUTOTRACE [ Off | On | Traceonly ]

[ Explain | Statistics ]

Generate the Execution Plan

• Can be used without tracing• Needs the plan_table table utlxplan.sql• Create the explain plan:

SQL> EXPLAIN PLAN FOR

2 SELECT last_name FROM hr.employees;

Query the plan_table Table Using dbms_xplan.display

Query plan_table to display the execution plans:Query plan_table directly.

Use script utlxpls.sql (hide Parallel Query information).

Use script utlxplp.sql (show Parallel Query information).

Use the dbms_xplan package.

SQL> SELECT *

2 FROM TABLE(dbms_xplan.display);

Metadata API in Oracle9i

A new package, DBMS_METADATA, is introduced. Using this package, you can extract metadata in:– Browsing mode, or– Programmatic mode where the program can specify:

The types of objects to be retrieved Various selection criteria Transformation of the output by default is XML, but

can be of any format (uses XSL).

Metadata API in Oracle9iBrowsing Example

The query can have a WHERE clause. Output is in SQL, but can be in XML format. Combine with a SPOOL statement for XML file Any combination of objects can be extracted,

depending on the result of the SELECT statement. Running a spool while extracting provides a file

that can be edited immediately.

SQL> SELECT dbms_metadata.get_ddl ('TABLE','SALES') 2 FROM dual;

Default Partition for List Partitioning

Create a DEFAULT partition for all values not covered by other list partitions:

CREATE TABLE customer...PARTITION BY LIST (state) (PARTITION p1 VALUES ('CA','CO'), PARTITION p2 VALUES ('FL','TX'), PARTITION p3 VALUES ( DEFAULT ) );

Range List Composite Partitioning

List(state)

Range (month)

CREATE TABLE customer ...PARTITION BY RANGE (month)SUBPARTITION BY LIST (state) ...;

p1_s1

p1_s2

p1_s3

p2_s1

p2_s2

p2_s3

p3_s1

p3_s2

p3_s3

p4_s1

p4_s2

p4_s3

< 3 < 6 < 9 < 12

'CA', 'CO'

Default

'FL', 'TX'

Composite Partitioning Using a Template

Use a subpartition template for:– Range list partitions– Range hash partitions

CREATE TABLE state_sales ...PARTITION BY RANGE (month)SUBPARTITION BY LIST (state)SUBPARTITION TEMPLATE (SUBPARTITION s1 VALUES ('CA,''CO') SUBPARTITION s2 VALUES ('FL','TX') )...

Rename Columns and Constraints

SQL> ALTER TABLE employees 2 RENAME COLUMN salary TO sal;

SQL> ALTER TABLE employees 2 RENAME CONSTRAINT sys_c002691 3 TO pk_employees_id;

RMAN: Control Archived Log Space Usage

Avoid errors caused by insufficient disk space for restored archived logs during recovery

Define size available for storage of archived logs copied to disk from backup sets

Use MAXSIZE option in conjunction with DELETE option

RMAN> RECOVER DATABASE 2> DELETE 3> ARCHIVELOG MAXSIZE 100K;

Backing Up the Server Parameter File

– Automatically backed up when CONFIGURE CONTROLFILE AUTOBACK = ON

– Explicitly backed up with BACKUP SPFILE

RMAN> BACKAUP COPIES 2 DEVICE TYPE sbt SPFILE;

RMAN> BACKUP SPFILE;

Persistent Configuration Parameters

Customizable configuration parameters simplify RMAN operations.

Default settings are set once and used for subsequent jobs.

A DBA can invoke RMAN and back up a database with one command: BACKUP DATABASE.

Oracle9i provides the new CONFIGURE command to override default settings persistently.

The configuration values are stored in the control file and are resynchronized to the recovery catalog as necessary.

Automatic Channel Allocation

This feature applies to BACKUP, COPY, and RESTORE commands.

A channel is automatically allocated if one is not explicitly specified in the RMAN command.

Default values are specified with the CONFIGURE command.

The benefit of this feature is a usability improvement due to the simplification of subsequent commands.

CONFIGURE CHANNEL Command

Used to configure settings that will be used for the channels (all or individual):CONFIGURE CHANNEL [n] <channel_option_list>;

channel_option_list := TYPE, NAME, PARMS, CONNECT STRING, DEBUG, FORMAT, TRACE, MAXPIECESIZE, RATE, MAXOPENFILES, SEND

Enterprise Manager Backup Wizard

Backup Wizard: Deletion of Archived Logs

Backup Wizard: Override RMAN Configuration

DBNEWID Utility

The DBID of a database The DBNAME of a database Both the DBNAME and DBID of a database

d:\>nidDBNEWID: Release 9.2.0.1.0 - ProductionCopyright (c) 1995, 2002, Oracle Corporation. All rights reserved.Keyword Description (Default)----------------------------------------------------TARGET Username/Password (NONE)DBNAME New database name (NONE)LOGFILE Output Log (NONE)REVERT Revert failed change NOSETNAME Set a new database name only NOAPPEND Append to output log NOHELP Displays these messages NO

Shared Pool Advisory

SQL> SELECT shared_pool_size_for_estimate AS pool_size, 2 estd_lc_size, estd_lc_time_saved 3 FROM v$shared_pool_advice;

POOL_SIZE ESTD_LC_SIZE ESTD_LC_TIME_SAVED--------- ------------ ------------------ 32 8 7868 40 15 7868 48 17 7868 56 17 7868 64 17 7868 72 17 7868 80 17 7868 88 17 7868 96 17 7868

Enterprise ManagerShared Pool Size Advisor

Mean Time To Recover (MTTR) Advisory

Collect statistics by setting initialization parameters– FAST_START_MTTR_TARGET to non-zero value– STATISTICS_LEVEL to TYPICAL or ALL

View estimated overhead for different settings of FAST_START_MTTR_TARGET

– In the rows of the view v$mttr_target_advice

– Through the Enterprise Manager graphical interface to this view

View MTTR Advisory with Enterprise Manager

V$PGA_TARGET_ADVICE

TARGET_MB CACHE_HIT_PERCENT ESTD_OVERALLOC_COUNT---------- ----------------- -------------------- 63 23 367 125 24 30 250 30 3 375 39 1 500 58 0 600 59 0 700 59 0 800 60 0 900 60 0 1000 61 0 1500 67 0 2000 76 0 3000 83 0 4000 85 0

PGA Sizing Advice Conclusions

LOW_KB HIGH_KB OPTIMAL ONEPASS MPASS------ ------- ------- ------- ------- 8 16 156107 0 0 16 32 148 0 0 32 64 89 0 0 64 128 13 0 0 128 256 58 0 0 256 512 10 0 0 512 1024 653 0 0 1024 2048 530 0 0 2048 4096 509 0 0 4096 8192 227 0 0 8192 16384 176 0 0 16384 32768 133 14 0 32768 65536 66 103 0 65536 131072 15 47 0131072 262144 0 48 0262144 524288 0 23 0

PGA Sizing Advisor Output in Enterprise Manager

Data Compression

CREATE TABLE employees( employee_id INTEGER, first_name VACHAR2(20), … ) COMPRESS;

CREATE TABLESPACE sample   DATAFILE 'sample01.dbf' SIZE 20M   DEFAULT COMPRESS;

CREATE TABLE countries( country_id CHAR(2), country_name VARCHAR2(40), region_id NUMBER ) NOCOMPRESS TABLESPACE sample;

Data Compression Optimization:Enabling Row Movement

CREATE TABLE employees (employee_id NUMBER, first_name VARCHAR2(20), last_name VARCHAR2(30), ...) ENABLE ROW MOVEMENT;

(both partitioned and nonpartitioned)

Locally Managed SYSTEM Tablespace

Create databases with a locally managed SYSTEM tablespace:

CREATE DATABASE mydb ...DATAFILE 'system01.dbf' SIZE 100M EXTENT MANAGEMENT LOCAL...;

Flashback Queries-- Query based on past SCN number:SELECT employee_id, manager_idFROM employeesAS OF SCN 81591;

-- Find changes made between 1-2 hours ago:SELECT a.last_name, b.last_nameFROM employees AS OF TIMESTAMP SYSDATE-1/24 a FULL OUTER JOIN employees AS OF TIMESTAMP SYSDATE-2/24 b ON (a.employee_id = b.employee_id)

-- Create new table based on old data:CREATE TABLE new_employees ASSELECT * FROM employees AS OF SCN 90932;

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Next Steps….

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