Oracle History #5

New Features for
Administrators
(Oracle8i)

April, 2001

CloudBox

Jang Kyung Sang

Oracle8i New Features http://www.ggola.com/

Oracle8i New Features for Administrators

Course

1. Java in the database

2. Optimizer and Query Improvements

3. Summary Management

4. Indexes and Index-Organized Tables

5. Basic Partition

6. Partition Maintenance

7. Composite Partitioning

8. Added New Features for partition

9. Universal Installer Migration and Upgrade

10. Tablespace Management

11. Database Resource Manager

12. Manageability Features

13. Availability and Recoverability

14. Features of Net8

15. SQL*Plus, PL/SQL and National Language Support

16. Database Security

17. Partial addition for Oracle8i

jkspark@hanafos.com -2-


1. Java in the database

What does Oracle8i support for java?

.

Open, portable, productive, internet computing language

Oracle8i enterprise class java server
- Java Virtual Machine integrated with Database
- use java anywhere PL/SQL used
- productive programming tools
- industry standard components

Oracle8i java application server platform
application java solution
.

Supported three products for building java database application

- standards-compliant JDBC drivers to access Oracle from JAVA
applications

- precompiler(SQLJ) for embedding SQL in java applications

- Oracle JDeveloper (JDBC, SQLJ, complete development
environment)

CF. Oracle8i JVM(Java
virtual machine) . EJB(Enterprise java bean)
transaction server CORBA clients
.

Five major components that integrated JVM with Oracle8i

- Oracle JVM Javasoft JDK specification Oracle
architecture optimizing .

- Embedded JDBC Driver JVM server
locally SQL and PL/SQL access .

- SQL and PL/SQL Inter-Language Method Services
mechanism JAVA call .
SQL PL/SQL call
C language external procedure ‘call
out’ standard mechanism .
, calling mechanism Oracle8i
SQL and PL/SQL Java call .



- Net8 java program SQL
‘publishes’ SQL Java access
.

- CORBA IIOP(Internet Inter-ORB
Protocol) . RDBMS access second
protocol ( Net8( SQL*Net) first
protocol ) Oracle8i
java CORBA2.0-compliant object request broker
embed CORBA
RDBMS call in and call out .
CF. java stored program ORB ‘published’
clients RDBMS java program access alternate
mechanism .

Major components of JVM

- SQLJ Translator : JAVA and SQL program
.

- Object Memory Management : allocate and free memory in
standard chunks called object memories.

- Memory manager/Garbage collector : Oracle database
environment manager JVM memory
heaps, allocating and collecting object memories
manage .

- Java class loader : Standard “.class” format and in a
compressed form Oracle VM other systems
java binaries interchange . (both export
and import)

- Bytecode compiler : “.class” java binary standard java
program translate .

- Interpretation/run-time : execute standard java binaries.

- Native compilation : C language java program
execution performance .

- Library manager : java program manage .

- Standard library : java API specification(java.lang, java.io,
java.math, and java.util) standard libraries Oracle
Java VM support .

CF. The java interpreters and compilers are based on the JDK 1.1.6
standards



Using JAVA

Integrated Java, SQL, and PL/SQL

- Integration : Java SQL and PL/SQL call ?
SQL and PL/SQL Java call ?

Java call SQL and PL/SQL

- Java standard JDBC interface database SQL
and PL/SQL CALL .

- Java VM OCI thin JDBC drivers interface
standard JDBC driver embed .

- , outside database JDBC
java application code
Oracle Java VM .

- architecture outside or within RDBMS
java and SQL same interface
application partitioning flexibility and efficiency
.

SQL and PL/SQL call java

- SQL and PL/SQL java call SQL
PL/SQL call mechanism .

- Oracle8i java stored procedure PL/SQL
automatic dependency-checking mechanisms
java call .

- Oracle8i new DDL extensions “create
procedure as java” java stored procedure,
function, and triggers .

- Oracle8i PL/SQL namespace java
stored procedure any PL/SQL
.



What is JDBC?

JDBC(Java Database Connectivity)

- JDBC java RDB access
standard set of java classes .

- JDBC javasoft SQL92 syntax
and types . mechanisms java
client database automatic data streaming .

- JDBC Oracle performance improvement
array interface vendor-specific
extensions .

JDBC drivers

- JDBC Thin driver : web browser applets
. (means thin client) driver RDBMS directly
communicating java sockets
client installation .

- JDBC OCI : driver Oracle Call Interface
Net8 RDBMS engine communicating
client OCI library .

- JDBC KPRB : driver java stored procedure
server side OCI Oracle KPRB library
.

- drivers the same syntax and APIs and oracle
extensions java application very
portable . , connect string minor
modification application 3
.

Features in JDBC Drivers

- 3 JDBC drivers Javasoft JDBC 1.22
specification JDBC 2.0 specification
. , JDBC 2.0 specification client side
XA support .
CF. server side driver XA specification
JDBC 2.0 specification .

- Oracle JDBC drivers standard JDBC driver Oracle
specification extensions important features .
1. access to Oracle7 types (like ROWIDs and REFCURSORs)
2. access to Oracle8i object-relational extensions, REFs, Lobs,
and BFILEs



3. performance enhancement with operation to prefetch rows
and the array interface
4. access to PL/SQL stored procedures with Oracle7 and 8
5. access to java stored procedures with Oracle8i
6. access across all Net8 certified firewalls

SQLJ

SQLJ Oracle Pro*C precompilers
Java application embedded SQL
.

Preprocessor embedded SQL statements SQLJ
Java code(with JDBC call) translate .

SQLJ generated code 100% compliant with Javasoft
JDBC specification .

Improve developer productivity

- smaller, cleaner, simpler code than JDBC

- SQL syntax errors and identification of SQL/Java type
mismatches detection code
quality improvement

- JDeveloper Java tool integration

- Standard language specification, compatible translators

- Oracle Translator standard compliant

- SQLJ applications binary portability
(property) platforms different vendor’s database
portable .

SQLJ supports

- SQLJ JDBC application programs
. (concise more than JDBC. easier to write
or maintain)

- 3 SQLJ .
1. JDBC (character string,
prepare and execute statements, and bind and define
variables) directly embed SQL statements
.
2. SQL statements Java bind variables and expressions
.



3. application simple default connection
and other syntactic elements features .

- During the translation phase, SQLJ detects SQL semantic
errors and Java and SQL type mismatches.

- SQLJ provides strong typed queries through the use of SQLJ
Iterators.(first-class java types for cursors)

- SQLJ SQL precompilation techniques run-
time execution more efficient . precompiling
Oracle SQLJ executions .

Code example JDBC VS SQLJ

- JDBC
Java.sql.CallableStatement stmt;
Connection conn;
ResultSet results;

Conn = DriverManager.getConnection 9”jdbc:default”);
stmt = conn.prepareStatement
(“select ename from emp where sal > ? and deptno = ?”);
stmt.setInteger(1, salparm);
stmt.setInteger(2, deptnoparm);
results = stmt.executeQuery();

- SQLJ
ResultSet results ;

#sql results =
{ select ename from emp
where sal > :salparm and deptno = :deptnopark} ;

Using SQLJ with Oracle

- SQLJ JDBC run-time environment deployed
configuration deployed .
CF. SQLJ run-time : Java + JDBC driver

- SQLJ applications deploy JDBC
driver . Oracle or users
JDBC/OCI/thin JDBC driver .

- Oracle8i Java VM embedded SQLJ translator
Oracle SQLJ java
stored procedures and triggers .

- Write program in SQLJ --> SQLJ translator : converts to java +
JDBC --> run the program



Java program

Java stored programs
- open alternative complementing PL/SQL

- java is fully functional. PL/SQL Java
.

- PL/SQL SQL-intensive SQLJ java stored
procedure .

- Java stored procedures 3 run-time contexts
.
1. stored functions and procedures (java program SQL
)
2. all triggers java .
3. java object-relational methods .

Developing

1. write java stored programs

2. Java VM load java code. Java classes
load .
- SQL*Plus “create java ddl”command
- standard Oracle utility “LOADJAVA”

3. publish the java procedure to SQL.
- expose the top-level java entrypoint
- map parameters and SQL and PL/SQL datatypes
- set up appropriate user privileges

4. SQL or PL/SQL call java program
CF. Oracle PL/SQL call SQL or
PL/SQL java program call syntax
.

Example (java installation . Refer to page 11)

create or replace java source named "NewJava" as public class JavaMaster {
static public String Msg(String guys) { return "Good morning " + guys ; } }
/
create or replace function JavaFunc (str varchar2) return varchar2 as
language java name 'JavaMaster.Msg (java.lang.String) return java.lang.String' ;
/
SQL> select JavaFunc('girls') from dual ;
JAVAFUNC('GIRLS')
--------------------------------------------------------------------------------
Good morning girls



Components

Develop server-side business logic as distributed components
- components improve developer productivity in following
ways.

1. reuse server-side business logic

2. improve application design as reusable modules

3. simplify deployment in a multitier environment

Support java component programming models

- Oracle8i traditional CORBA servers Java
implemented . , ORB Java VM java
applications .

- EJB(the industry standard enterprise javabeans)
component model database java
.
Simple declarative transaction commit or rollback
transaction operations .

CF. Java or EJBs implemented CORBA servers
Oracle8i MTS .

Server-side ORB (on MTS)

- IIOP listener : Oracle8i standard CORBA/IIOP binding
protocol extended .(Net8)

- IIOP dispatcher : Oracle8i IIOP-based method
invocations extened .

- Oracle8i integrates a CORBA 2.0 ORB.

- MTS platforms : Java VM MTS .
MTS .

Enterprise JavaBeans (EJBs)

- EJBs is a server-oriented component model for Java.
Oracle8i EJBs transaction server platforms EJB
1.0 specification .

- Significant advantages using EJBs
1. developers advanced system programming
skills .
2. Pure Java definition D/COM, CORBA

jkspark@hanafos.com - 10 -


dependency .
3. platform vendors EJB
.

Java Configuration

Java VM classes installation

- Java VM manually initialize script
.

- $ORACLE_HOME/javavm/install/initjvm.sql
(user by “SYS”)
CF. test 1 .

- script 4000 java classes
initial package .

- DBMS_JAVA package
only used internally by Oracle .

- Needed initial parameter values for executing initjvm.sql :
shared_pool_size 50M
java_pool_size 50M
rollback segment 100M

Java-related initial parameter

- shared_pool_size : static java variables UGA
space

- java_pool_size : shared java objects
space java class loading .
large java application system 50M
java stored procedure 20M
.

- java_soft_sessionspace_limit : size user’s
session java memory usage RDBMS trace file
. default 1M.

- java_max_sessionspace_size : size out-of-
memory failure session kill . Default 4G
invisible java
programs memory usage
.

CF. java-related memory application system java
setting .



Internet File System

iFS Windows OS directories
database access .

Oracle8i Oracle8i Java VM Java
application .

Oracle iFS several different protocols access .

- SMB : MS windows95, 98, NT protocol

- HTTP : Web browser and network computer

- FTP : FTP clients command line

- SMTP, IMAP4, POP3 : e-mail protocol

Data integration

- iFS application developers 3
APIs , Java, CORBA, and PL/SQL .

- iFS document system document
automatically decompose(parse)
document recompose(render) .

- XML(Extended markup language) .

CF. iFS application
.



2. Optimizer and Query Improvements

Stored Outline

Optimizer plan stability

- Optimizer feature Oracle8i
well-tuned applications SQL hints
(good access path) SQL
.

- Plan Equivalence : plan
1. SQL Statement text must match
2. Plans are maintained through :
- new oracle versions
- new statistics on objects
- init.ora parameter changes
- database reorganization
- schema changes

CF. table index stored outline index
.

Creating stored outlines

- Outline oracle automatic or SQL
creation rule-based or cost-based
optimizers .
oracle outline cost-based optimize
.

- Session init.ora parameter create_stored_outlines
parameter true default category
category name category stored
outlines .

- Test initial parameter database
restart error parameter
create_stored_outlines

SVRMGRL> show parameter
SQL> select name from v$parameter
. Oracle8.1.5 Reference
parameter session level
test .

CF. system user “create any outline” privilege outline
user grant .



- Session
category name default
category name .

SQL> alter session set create_stored_outlines = true ;
Session altered.
SQL> select d.dname, e.ename from emp e, dept d
2 where e.deptno = d.deptno ;
DNAME ENAME
-------------- ----------
RESEARCH12 SMITH
SALES12 ALLEN
..............
ACCOUNTING12 MILLER
14 rows selected.………..
SQL> alter session set create_stored_outlines = false ;
SQL> select * from user_outlines ;
NAME CATEGORY USED TIMESTA VERSION
SQL_TEXT
----------------------------------------------------------------------------------------------------------------
SYS_OUTLINE_0107311031050000 DEFAULT UNUSED 31Jul01 8.1.6.2.0
select d.dname, e.ename from emp e, dept d where e.deptno = d.deptno

SQL> alter session set create_stored_outlines = cat_emp ;
Session altered.
SQL> select e.ename, d.loc from emp e, dept d where e.deptno = d.deptno ;
ENAME LOC
-------------- ----------
SMITH DALLAS189
ALLEN CHICAGO189
..............
MILLER NEW YORK189
14 rows selected.………..
SQL_TEXT
-------------------------------------------------------------------------------- -------------------------------
SYS_OUTLINE_0107311026420001 CAT_EMP UNUSED 31Jul01 8.1.6.2.0
select e.ename, d.loc from emp e, dept d where e.deptno = d.deptno
select * from user_outlines
SQL> alter session set create_stored_outlines = false ;

- category DEFAULT
category
. outline name
system default
.

- Outline parameter false select * from outlines
stored outline .

- outline category shared_pool pinning
execution plan .



- stored outline .

SQL> create or replace outline emp_join for category cat_emp
on select /*+ FULL(DEPT) */ d.dname, e.ename from emp e, dept d
where e.deptno = d.deptno order by 1, 2 ;
Outline created.
SQL_TEXT
----------------------------------------------------------------------------------------------------------------
select e.ename, d.loc from emp e, dept d where e.deptno = d.deptno
select * from user_outlines
EMP_JOIN CAT_EMP UNUSED 31Jul01 8.1.6.2.0
select /*+ FULL(DEPT) */ d.dname, e.ename from emp e, dept d
where e.deptno = d.deptno order by 1, 2

- outline name outline sys
name . category
.

category .

Using stored outlines

- outline command .

SQL> alter session set use_stored_outlines = true or category_name ;

- create category name true
outline .

- Category category
default category text match .
, category match outline
default category outline outline
.

- To determine a SQL statement’s execution plan
1. shared pool matching text and outline category
2. 1 data dictionary outline query
3. 2 SQL outline execution
plan .
4. 2 normal methods(non-outline) .

- , outline hints outline
user_outlines user_outline_hints
view
.



Maintaining stored outlines
- Package ‘OUTLN_PKG’
1. drop_unused : drop unused outline
2. drop_by_cat : drops categories of outlines
3. update_by_cat : rename categories

- ALTER OUTLINE outline_name command
1. rename to new_outline_name ; (outline name )
2. rebuild ; (outline execution path )
3. change category to new_category_name ; (category )

Database creation automatically - Stored outlines in tables in schema OUTLN
schema OUTLN 1. OL$ : outline name, category, timestamp, statement text
tables outlines . 2. OL$HINTS : hints for the outlines in OL$
(system tablespace )
- Data dictionary view
1. DBA/ALL/USER_OUTLINES
2. DBA/ALL/USER_OUTLINE_HINTS

DBMS_STATS

This package enables you to generate and manage statistics for
cost-based optimization. The statistics can reside in the data
dictionary or in a table created in the user’s schema. Only
statistics stored in the dictionary itself will have an impact on
the cost-based optimizer. (but cannot gather cluster statistics)

Generating statistics
- Gathering sub-procedure
1. gather_index_stats : index
2. gather_table_stats : table, column and index
3. gather_schema_stats : all objects in a schema
4. gather_database_stats : all objects in a database

- usage for table statistic
DBMS_STATS.GATHER_TABLE_STATS (
schema, table, partition, sample size(%), block sample?(or row),
columns, parallelism degree, table and all partitions,
cascade to indexes) ;

- How can you gather the statistics ?
1. statistics serially or in parallel index
statistics only serially
2. random sampling or computed
3. block sampling faster than row sampling
4. column lists
5. table index statistics
6. statistics tables can hold statistics to enable you to
experiment with different sets of statistics.



Moving statistics

scott emp table export
file dump database import statistic
import source database target database
.

1. table statistics .
usage : dbms_stats.
gather_table_stats(schema, table, partition, sample size(%), block
sample?(or row), columns, parallelism degree, table and all partitions,
cascade to indexes)
meaning : table statistic . (index statistics
cascade to indexes TRUE )
example :
SQL> exec dbms_stats.gather_table_stats( 'SCOTT', 'EMP',
NULL, 20, FALSE, 'FOR ALL COLUMNS', 4, 'DEFAULT',
TRUE) ;

2. Statistics table schema .
usage : dbms_stats.
create_stat_table(‘SCOTT’, ’stat_tab_name’, ’tablespace_name’)
meaning : data dictionary statistics export
table .
example :
SQL> exec dbms_stats.create_stat_table('SCOTT',
'STAT_SCOTT', 'USERS') ;

3. Statistics data table copy .
usage : dbms_stats.
export_table_stats(‘SCOTT’, ‘EMP’, NULL(partition ),
‘stat_tab_name’, ‘stat_id’(ID ), TRUE(index stat) ) ;
Source Database meaning : statistics user’s table export .
table export backup or copy .
example :
SQL> exec dbms_stats.export_table_stats('SCOTT', 'EMP',
NULL, 'STAT_SCOTT', 'Stat 20010731', TRUE) ;
File dump exp/imp
4. database table file dump
OR export table import database
Database link copy link copy table ,
stat_scott table database
data data dictionary
.
usage : dbms_stat.
Target Database import_table_stat (export_table_stas argument)
meaning : schema table data dictionary
.
example :
SQL> exec dbms_stats.import_table_stats('SCOTT', 'EMP',
NULL, 'STAT_SCOTT', 'STAT 20010731', TRUE) ;



5. user schema table
drop .
usage : dbms_stats.
drop_stat_table(‘SCOTT’, ‘stat_tab_name’)
meaning : table drop .
example :
SQL> exec dbms_stats.drop_stat_table ('SCOTT',
'STAT_SCOTT') ;

Top-N SQL

Now Oracle8i supports ordering of views and in-line views.

Sorts only the required number of rows

- Oracle8i in-line view
order by .

- Oracle rownum < 3
2 value memory rows
2 value .

- Example : order by
SQL> select * from
(select empno, deptno, hiredate from emp
order by hiredate desc)
where rownum < 3 ;

EMPNO DEPTNO HIREDAT
---------- ---------- -------
7876 20 12Jan83
7788 20 09Dec82

SQL> select * from
(select empno, deptno, hiredate from emp)
where rownum < 3 ;

EMPNO DEPTNO HIREDAT
---------- ---------- -------
7369 20 17Dec80
7499 30 20Feb81

- Query (searching for the top few values) run considerably
faster in Oracle8i.



ROLLUP and CUBE

Aggregate operators

group by rollup and cube
crosstab report .

1 2 3 Total
1 2 3 6
1 2 3 6
Total 2 4 6 12

Rollup operation

SQL> select , , sum(year) from emp
group by rollup( , );

- group by total grand total
.

sum(year)

1 1
2 2
3 3
6
1 1
………………..
………………..
6
………………..
12

- function data result rows n types( ) m
status( ) ROLLUP group by (n X
(m+1)) + 1 = ? rows .

- (2 X (3+1)) + 1 = 9 rows .



Cube operation

SQL> select , , sum(year) from emp
group by cube( , )
order by , ;
sum(year)

1 1
2 2
ROLLUP 3 3
6
1 1
2 2
+ 3 3
6
CUBE 1 2
2 4
3 6
GRAND 12

- function data result rows n types( ) m
status( ) CUBE group by ((n+1) X
(m+1)) + 1 = ? rows
.

- .
, (type + 1) X (status + 1) .
(2 + 1) X (3 + 1) = 12 .

Grouping function

Rollup and cube total value null
. data value null
null .
new function grouping .

- grouping(column_name) decode 0
value null 1 rollup or cube
null .

- , .
decode(grouping(column),1,’null of total’,’value’)



TRIM

New function trim ltrim rtrim .

ANSI .

Using function
SQL> select last_name, trim(leading ‘X’ from last_name)
as trimmed
from emp where last_name like ‘X%’ ;

- TRIM(leading ‘X’ from column) : LTRIM

- TRIM(trailing ‘X’ from column) : RTRIM

- TRIM(both ‘X’ from column) : L + R (default)

- TRIM( ‘X’ from column) : both .

- TRIM(last_name) : character
space trim characters .

CF. trim character .
trim character only one character .

New and Obsolete

Obsolete parameter :
sort_direct_writes, sort_write_buffers,
sort_write_buffer_size, sort_read_fac

New parameter :
sort_multiblock_read_count
this parameter define the number of blocks read from
temporary segments during sorts.
(db_multiblock_read_count )



3. Summary Management

Materialized Views

In general, this will be used for Data Warehouse, Distributed
Computing, Mobile Computing

Summary and aggregate data

- View view base table data view
, summary and aggregate data(pre-computed)
data segment view .

- , expensive and complex joins view .

Create materialized view day_of_booking as
Select bkg_no, sum(amt) as total_amount
From booking
Where bkg_dt = sysdate
Group by bkg_no ;

- M-View SQL base
table M-View
.( query rewrite )
CF. The process of modifying a query to use the view rather
than the base table is called a query rewrite.

- Create materialized view is synonym for create snapshot.

- M-View
SQL> create materialized view view_name build deferred
refresh …. as select …..
“build” clause M-View
. Build clause “immediate or
deferred” option .
1. immediate
2. deferred refresh .
CF. build clause default “build
immediate” .

CF. remote tables .

CF. M-View order by clause
creation
refresh . , order by
clause M-View query definition .
query performance order by clause
column M-View select list column
index recommend .



Materialized view refresh option

Base table M-View base table sync
. ‘Refresh’ .

- Complete : Base table
M-View
M-View query
data .

- Fast : last refresh
1. M-View log
2.Direct loader log (direct loads new rows
rowid M-Views refresh)

- Force : .
complete fast .
(This is default refresh type.)

- Never : Refresh .

CF. M-View system user user grant
‘create materialized view’ privilege .

Refresh mode : Refresh .

- ON DEMAND
Manually DBMS_MVIEW package
procedure .
1 …REFRESH(‘BOOKING’,PARALLELISM => 3);
>> specified M-View
2 …REFRESH_DEPENDENT(VN_FAIL_CNT, ‘EMP’) ;
>> M-Views on based 1 base tables
(number_of_failures out variable )
3 …REFRESH_ALL_MVIEWES ;
>> all M-Views

- Automatic Refresh
1. ON COMMIT ( synchronous) : base table
commit .
2. START WITH-NEXT(asynchronous) : specified time
supported complete mode only. (must initiate job
processes)

CF. , ON COMMIT M-View join or aggregate
views Oracle8.1.5 manual
only join view single table aggregate
.( Nested M-View
join and aggregate view fast on commit
)



Materialized view types (UNION set operation )

- joins and aggregates
type M-View fast refresh
new data direct path method add fast
refresh . The where clause can contain inner
equi-joins only.(no outer joins)
1. group by column select list .
2. function : sum, count(x), count(*), count(distinct x), avg,
variance, stddev, min, max

- single table aggregate
M-View log fast refresh count
sum count count or sum
group function count sum
. count(*) where
clause .
1. function : count, sum, avg, variance, stddev

- only joins : fast refresh
1. each detail tables M-View log
2. select list detail table rowid .
3. outer join inner table column
unique constraint .
CF. M-View log rowid column
speed up refresh M-View rowid
column index recommend .
CF. detail tables rowid tables
tables DML fast refresh .

Test M-View

- Test Oracle8.1.6.2 M-View
. Oracle Manual

.

- , Oracle version
Oracle9i fixed Test
.

- Refresh complete .
dbms_mview package refresh

M-View
.

- Refresh fast on commit on demand
M-View log Test
Query Rewrite Usage
.



Example
- complete on demand (joins and aggregates)
SQL> sho user
USER is "SYSTEM"

SQL> grant create materialized view to scott ;
Grant succeeded.

SQL> conn scott/tiger
Connected.

SQL> set timing on
SQL> set serveroutput on

SQL> create materialized view mv_emp_sales refresh complete on demand
2 as select e.empno, d.deptno, sum(sal) from emp e, dept d
3 where e.deptno = d.deptno group by e.empno, d.deptno ;
Materialized view created.
Elapsed: 00:00:46.95

SQL> select * from mv_emp_sales ;
EMPNO DEPTNO SUM(SAL)
---------- ---------- ----------
7369 20 52428800
....................
9022 95 6553600
21 rows selected.

EMPNO SAL update SQL> update emp set sal = 10 where empno = 9022;
256 rows updated.
.
SQL> commit ; MV creation
Commit complete. refresh
.
---------- ---------- ----------
7369 20 52428800
....................
9022 95 6553600
21 rows selected.
Refresh procedure
SQL> exec dbms_mview.refresh('MV_EMP_SALES') ;
PL/SQL procedure successfully completed.
. Elapsed: 00:00:48.04


---------- ---------- ----------
7369 20 52428800
....................
9022 95 655360
21 rows selected.

CF. M-View performance M-View
partitioning parallel operation
.



SQL> update emp set sal = 100 where empno = 9022 ;
256 rows updated.

SQL> commit ;
Commit complete.

refresh_dependent procedure SQL> declare
2 vn_fail_cnt BINARY_INTEGER;
3 begin
4 dbms_mview.refresh_dependent(vn_fail_cnt, 'EMP');
. 5 dbms_output.put_line(vn_fail_cnt);
6 end;
7 /
0

Elapsed: 00:00:47.74


---------- ---------- ----------
7369 20 52428800
....................
9022 95 6553600
21 rows selected.

- fast on commit (single table aggregate)
SQL> create materialized view log on emp
2 with rowid(empno, ename, job, mgr, hiredate, sal, comm, deptno)
3 including new values ;
Materialized view log created.

SQL> create materialized view mv_emp_sales refresh fast on commit
2 as select count(*), empno, sum(sal), count(sal)
3 from emp
log M- 4 group by empno ;
View . base Materialized view created.
table SQL> select * from mv_emp_sales ;
refresh COUNT(*) EMPNO SUM(SAL) COUNT(SAL)
commit refresh ---------- ---------- ---------- ----------
data 256 7369 204800 256
...........................
. 256 9022 25600 256
21 rows selected.

256 rows updated.

SQL> commit;
Commit complete.

COUNT(*) EMPNO SUM(SAL) COUNT(SAL)
---------- ---------- ---------- ----------
256 7369 204800 256
...........................
256 9022 2560 256
21 rows selected.



- fast on demand (single table aggregate)

SQL> drop materialized view log on emp ;
Materialized view log dropped.

SQL> drop materialized view mv_emp_sales ;
Materialized view dropped.

SQL> create materialized view log on emp
2 with rowid(empno, ename, job, mgr, hiredate, sal, comm, deptno)
3 including new values ;
Materialized view log created.

SQL> create materialized view mv_emp_sales refresh fast on demand
2 as select count(*), empno, sum(sal), count(sal)
log 3 from emp
MV . base table 4 group by empno ;
Materialized view created.

refresh procedure SQL> select * from mv_emp_sales ;
MV
COUNT(*) EMPNO SUM(SAL) COUNT(SAL)
---------- ---------- ---------- ----------
data . 256 7369 204800 256
.........................
256 9022 2560 256
21 rows selected.

256 rows updated.

SQL> commit;
Commit complete.

SQL> exec dbms_mview.refresh('MV_EMP_SALES') ;


Test join and COUNT(*) EMPNO SUM(SAL) COUNT(SAL)
---------- ---------- ---------- ----------
aggregate M-View 256 7369 204800 256
M-View log .........................
error fast refresh 256 9022 256000 256
21 rows selected.
refresh
data CF. M-View table
. prebuilt table M-View .
query rewrite . (start with-next refresh
M-View query rewrite )

CF. Nested Materialized Views : M-View fact(/detail/base)
table M-View user request
Nested Materialized View .
join only M-View base
table single-table aggregate M-View refresh
fast on commit join and aggregate M-View
performance . ,
space .



Query Rewrite

M-View base table
performance .
Oracle8i M-View statement ‘Query
Rewrite’ mechanism M-View
query query .

Query Rewrite Attributes

- M-View index transparent to
applications .

- Base table privileges M-View
M-View enable,
disable M-View control .

- Initial parameter : QUERY_REWRITE_ENABLED=TRUE
”QUERY REWRITE” privilege M-View enable .
DBMS_OLAP package has options to use M-Views

CF. Query Rewrite : grant query rewrite to username ;
“global query rewrite” for outside schema
“explicit select privilege” for M-View using different schema

Usage :
create materialized view mview_name
tablespace ts_name --> skip user default tablespace
parallel (degree 4) --> option
build immediate/deferred --> skip default immediate
refresh complete/fast/force/never --> skip default force
on demand/on commit/start with .… next ….
enable/disable query rewrite --> query rewrite
as select count(*), count(sal), sum(sal) from emp; --> query
restriction : join equip only aggregate
operator outermost part . (AVG(AVG(x))
) sequence, user, sys owner objects,
subquery order by, remote table, pl/sql function, having,
connect by, inline views, nested subquery, sysdate, rownum,
bind variable, raw or long raw .

case 1) select count(*), count(sal), sum(sal) from emp ; ==>
Oracle M-View
mview_name execution plan
performance .

case 2) select /*+ NOREWRITE */ count(),count(sal),sum(sal) from
emp ; ==> Case 1 norewrite hint
M-View base table execution
plan full table scan .



Example
- Creation materialized view for query rewrite
SQL> create materialized view mv_emp_sales tablespace users
2 parallel(degree 4) build immediate
start and next time 10 3 refresh complete start with sysdate+1/6/24 next sysdate+1/6/24
query 4 enable query rewrite as select e.empno, d.deptno, sum(sal) from emp e, dept d
rewrite enable 5 where e.deptno = d.deptno group by e.empno, d.deptno ;
MV Materialized view created.
Elapsed: 00:01:02.80
user_jobs
last date, next date 10 SQL> select job, what, last_date, next_date from user_jobs ;
JOB WHAT
---- -----------------------------------------------
.
243 dbms_refresh.refresh('"SCOTT"."MV_EMP_SALES"');
LAST_DATE NEXT_DATE
----------------- -----------------
20010802 14:35:31 20010802 14:45:31
SQL> select sysdate from dual ;
SYSDATE
-----------------
20010802 14:36:41
14 36 ---------- ---------- ----------
empno 9022 sal 10 7369 20 52428800
................
update . 9022 95 6553600
MV query 21 rows selected.

. user_jobs
256 rows updated.
next date SQL> commit ;
. Commit complete.

---------- ---------- ----------
7369 20 52428800
................
9022 95 6553600
38
21 rows selected.
refresh SQL> select sysdate from dual ;
. 45 SYSDATE
refresh -----------------
MV 20010802 14:38:20
( 1 )
46 40 query SQL> select sysdate from dual ;
SYSDATE
data
-----------------
. 20010802 14:46:41
, refresh
MV query SQL> select * from mv_emp_sales ;
“no rows selected” return EMPNO DEPTNO SUM(SAL)
. ---------- ---------- ----------
7369 20 52428800
................
9022 95 655360
21 rows selected.



- Query rewrite
SQL> select e.empno, d.deptno, sum(sal) from emp e, dept d
---------- ---------- ----------
MV SQL 7369 20 52428800
................
9022 95 655360
. ,
21 rows selected.
query rewrite .
Elapsed: 00:00:00.08
hint
query rewrite SQL> select /*+ NOREWRITE */
2 e.empno, d.deptno, sum(sal) from emp e, dept d
. 3 where e.deptno = d.deptno group by e.empno, d.deptno ;
---------- ---------- ----------
7369 20 52428800
................
9022 95 655360
21 rows selected.
Elapsed: 00:00:49.50
SQL> explain plan for select e.empno, d.deptno, sum(sal) from emp e, dept d
Explained.
SQL> select substr(lpad(' ',2*(level-1))||operation||' '||options
2 ||' '||object_name,1,79) "Plan View"
3 from plan_table
4 start with id=0
5 connect by prior id = parent_id
6 order by id;
Plan View
-------------------------------------------------------------------------------
SELECT STATEMENT
TABLE ACCESS FULL MV_EMP_SALES
SQL> delete plan_table;
plan
2 rows deleted.
query rewrite SQL> commit;
MV execution Commit complete.
plan hint SQL> explain plan for select /*+ NOREWRITE */
2 e.empno, d.deptno, sum(sal) from emp e, dept d
execution plan 3 where e.deptno = d.deptno group by e.empno, d.deptno ;
. Explained.
SQL> select substr(lpad(' ',2*(level-1))||operation||' '||options
2 ||' '||object_name,1,79) "Plan View"
3 from plan_table
4 start with id=0
5 connect by prior id = parent_id
6 order by id;
Plan View
-------------------------------------------------------------------------------
SELECT STATEMENT
SORT GROUP BY
NESTED LOOPS
TABLE ACCESS FULL EMP
INDEX RANGE SCAN XPKDEPT



Control Rewrite

- optimizer mode cost-based only . (rule base )

- QUERY_REWRITE_ENABLED : FALSE setting query
rewrite . dynamically instance
level(initial parameter) or session level(alter session
command) .

- QUERY_REWRITE_INTEGRITY : this parameter reset
dynamically for instance and session level.
1. ENFORCED(default) : consistency
query rewrite . (updated M-view and validated
constraints only)
2. TRUSTED : All updated M-Views and dimensions and
constraints with RELY flag are used for query rewrites.
(RELY flag constraint new features
invalid constraint valid
)
3. STALE_TOLERATED : last DML and relationships(are
declared) refresh all M-Views
rewrite .(data M-View validate )

CF. register M-View
QUERY_REWRITE_INTEGRITY parameter value
.

Support utility & System privileges

- SQL*Loader : Rowid range M-View
reference table direct path loading
HWMK data incremental refresh
.

- Export/Import :
1. M-View definition export & import (full mode or user mode)
2. MVDATA=Y export & import data in M-Views
MVDATA=N table ROWS=N .
( , M-View data segment
object )
3. MVBUILDDEFERRED=Y
export all M-Views definition and created for deferred
refresh

- M-Views privileges
. create materialized view
. create/drop/alter any materialized view
. query rewrite (enable and disable of own schema)
. global query rewrite (enable and disable of in the grantee’s
schema for query rewrite)



Registration of an Existing Materialized View

- Data Warehouse system ordinary user
tables summary and aggregate data tables
. tables table
build cost
. , data .

- table Query Rewrite
incremental refresh tables
M-View .

- M-View base table
M-View .( name table name )
SQL> create materialized view ….name on prebuilt table …

- prebuilt table M-View query
rewrite parameter query_rewrite_integrity
“TRUSTED” set .

- QUERY_REWRITE_INTEGRITY : (Oracle 8.1.6 )
enforced : M-View data relationship
query rewrite .
trusted : prebuilt table M-View data and RELY constraint
(17 constraints ) correct trust query
rewrite .
stale_tolerated : M-View valid query rewrite
maximum rewrite capability . , query
rewrite wrong result .
CF. Oracle 8.1.5 enforce/no_enforce/use_stale .

- , prebuilt table M-View drop table
drop .

Data dictionary for M-Views
- ALL_REFRESH_DEPENDENCIES :
dependent or container tables in the current schema

- DBA_MVIEW_AGGREGATES :
grouping functions in an aggregated M-Views

- DBA_MVIEW_ANALYSIS : M-Views information

- DBA_MVIEW_DETAIL_RELATIONS :
the named detail relations (base(fact) tables information)

- DBA_MVIEW_JOINS : information about the joined columns
of base tables

- DBA_MVIEW_KEYS : detail columns information about the
relations of DBA_MVIEW_DETAIL_RELATIONS



Dimension

Additional query rewrites are possible if summaries are
created at the lowest level of aggregation, supported with
dimensions.

What is a Dimension ?
- data dictionary structures that define hierarchical relationship
between pairs of columns and column sets. based on existing
columns(M-View segment )

- dimension optional highly recommended
1. enable additional query rewrite possibilities
(without use of constraints, M-Views )
2. hierarchies( ) summary .
3. can be used by OLAP tools ( DBMS_OLAP )

- level dimension . date
month month quarter quarter year
level query
rewrite .
CF. create dimension attribute level
level value column
.( “ ” level
“ ” )

SQL> conn system/manager
Connected.

SQL> grant create dimension to dimuser ;
Grant succeeded.

SQL> conn dimuser/dimuser
Connected.

SQL> create table emp (
2 hiredate date,
3 month varchar2(2),
4 month_name varchar2(10),
5 quarter varchar2(1),
6 year varchar2(4)) ;
Table created.

SQL> Create dimension emp_dim
2 Level hiredate is emp.hiredate
3 Level month is emp.month
4 Level qtr is emp.quarter
5 Level yr is emp.year
6 Hierarchy calendar_rollup (
7 Hiredate child of
8 Month child of
9 Qtr child of yr )
10 Attribute month determines month_name ;
Dimension created.



- 3 multiple hierarchies time
dimension .
SQL> create table sales (
2 sal_date date,
3 month varchar2(2),
4 quarter varchar2(1),
5 year varchar2(4),
6 season varchar2(6),
7 week varchar2(1),
8 dayweek_name varchar2(3),
9 month_name varchar2(3)) ;

Table created.

SQL> create dimension sales_dim
2 level sal_date is sales.sal_date
3 level month is sales.month
4 level quarter is sales.quarter
5 level year is sales.year
6 level season is sales.season
7 level week is sales.week
8 hierarchy cal_rollup (
9 sal_date child of
10 month child of
11 quarter child of
12 year )
13 hierarchy week_rollup (
14 sal_date child of
15 week )
16 hierarchy season_rollup (
17 sal_date child of
18 season )
19 attribute sal_date determines sales.dayweek_name
20 attribute month determines sales.month_name ;

Dimension created.

SQL> select * from user_dimensions ;

OWNER DIMENSION_NAME INVALID REVISION
---------- -------------------- - ----------
DIMUSER EMP_DIM N 1
DIMUSER SALES_DIM N 1

CF. time level, category level, location level
.( , , )



- Based on multiple tables : 2 table
1. Keys and attributes correspond to columns
2. All attributes and keys for one level must belong to one table
3. child columns FK define
.
Create dimension nation_dim
Level goo_cd is goo.goo_cd
Level city_cd is city.city_cd
Level do_cd is dochung.do_cd
Hierarchy nation_analysis (
Goo_cd child of
City_cd child of
Do_cd
Join key goo.city_cd references city.city_cd
Join key city.do_cd references do_cd)
Attribute city_cd determines (city.city_name,
city.city_mayor) ;

Query Rewrite Situations

- Exact match : selected columns and join conditions match

- Aggregate rollup : summary grouping “lower than” query
grouping

- Aggregate to all : more dimensions in summary

- Summary joinback : a column not in summary, but derivable
used by query

CF. exact match dimension
query rewrite .

Data dictionary for Dimensions

- DBA_DIMENSIONS : dimension objects

- DBA_DIM_LEVELS : dimension levels

- DBA_DIM_LEVEL_KEY : column and position of dimension
level

- DBA_DIM_ATTRIBUTES : relationships between a dimension
level and a functionally dependent column

- DBA_DIM_HIERARCHIES : dimension hierarchies

- DBA_DIM_CHILD_OF : hierarchical relationships (a pair of
levels in a dimension)

- DBA_DIM_JOIN_KEY : information between two dimension
tables


Oracle History #5

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