2008 2086 gangler

Mike Gangler

Ithaka / JStor

Session #

2086

2086/Migrating SQL Server 2005

Applications to Oracle

Speaker and Company Information

• Database Specialist with JSTOR – www.jstor.org

• 20+ Years DBA experience

• Presented Collaborate in ’07, SEMOP, Regional user Groups and at many IOUG-Alive events

• Experience with FOCUS, IMS DB/DC, DB2, Sybase, and MSSQL 6.5 databases prior to assignment.

• JSTOR - is a not-for-profit organization dedicated to helping the scholarly community discover, use, and build upon a wide range of intellectual content in a trusted digital archive. We collaborate

with organizations that benefit the scholarly community.

Agenda

• Introduction

• Overview of Problem

• Basic and Fundamental Differences

• Database Locking

•

• Data Objects

• Data Types

• Data Access – DML and Examples

Introduction

• This session will describe the lessons learned during the process of converting an MSSQL database application to Oracle.

• Session targeted towards Oracle DBA’s with little or no MSSQL experience.

• JSTOR purchased a 3rd party product that was using primarily MSSQL.

• Agreement was that JSTOR would convert MSSQL patches and coding to Oracle (If and when needed).

• Project started in 2006 and we launched the new product in April 2008.

• Using Oracle 10G release 2 and Grid Control on Sun Solaris X86-64 machines

• 3rd Party using SQL Server 2005

Overview of Problem

• JSTOR Is primarily a Oracle Shop

• 3rd Party is primarily a MSSQL Shop

• Coding was supposed to be “Database Agnostic”

• Limited assistance from 3rd Party

• Limited experience with MSSQL

• 2 development centers – Santa Clara and Ann Arbor– code control

– version control

– little or no communication

• 3 – 5 patches a day

Basic and Fundamental Differences

• Database, Instance and Storage Architecture

– Terminology

– Characteristic Differences

– Comparison of Core Objects

– Storage Architecture

– Data Blocks, Extents and Segments

– Memory Address Space – Oracle

– Memory Address Space – MSSQL

– Process and Thread-based Architecture

– Background Processes

Basic and Fundamental Differences -

Database and Instance

• Terminology –

– Oracle Instance = Memory and Processes related

to a Database.

– Oracle Database = Files containing application

and system information

– MSSQL Instance = set of binaries isolating the

SQL Server database Engine Services.

• Every Instance will have its own system database and separate Admin parms.

– MSSQL Database = Oracle schema with a Master DB (System Tables).

Basic and Fundamental Differences –

Database and Instance

32K File Groups65KMax # of tablespaces

32TB64 GbMax log file size

50Based on Server Resources

Instances Per Server

1EB4PBMaximum DB Size

8KB16KBMaximum Block Size

2 Million Blocks4 Million blocksMaximum Blocks Per File

32K65KMaximum # of Files

32K File Groups65KMax # of tablespaces

16TB64GbMaximum File Size

8KB2KBMinimum Block Size

SQL ServerOracle Characteristic


Comparison of Core Objects

XML Schema CollectionXMLDB

N/APackage

Service Broker QueueStreams

FunctionFunction

Stored ProcedureProcedure

IndexIndex

ViewView

N/ASequence

TypeObject Type

SynonymSynonym

TableTable

SQL ServerOracle

Basic and Fundamental Differences – Storage

Architecture

• Physical

– Oracle Data file = MSSQL data file or Device

• Logical

– Oracle tablespace = MSSQL File Group

– Oracle Segment = MSSQL Heap/Index

– Oracle Extent = MSSQL Extent

– Oracle Blocks = MSSQL Pages

Basic and Fundamental Differences –Data

Blocks, Extents and segments

• Smallest unit of logical storage

– Oracle = Block

– MSSQL = Page

• Block size

– Oracle is variable

– MSSQL is fixed at 8kb

• Extent size

– Oracle is variable

– MSSQL are fixed at 64kb

Basic and Fundamental Differences –Memory

Address Space - Oracle

• Memory Allocation Concepts – Oracle

– Oracle is static

– Allocated at Startup

– MSSQL is Dynamic

– Variables set by administrator

– ASSM introduced in Oracle 10g

Basic and Fundamental Differences –Memory

Address Space – MSSQL 2005

• Memory Allocation Concepts – MSSQL 2005

– Allocations are constantly changed based on RDBMS needs and operating system needs (Self Tuning).

– Allocation is dynamic at higher level (Memory pool, etc.) and lower level ( Buffer cache, procedure cache, etc.) components.

– Very Few configurable parameters

– Min server memory and max server memory settings

• Memory address range

– Leveraging Address Windowing Extensions (AWE)

Basic and Fundamental Differences –Process

and Thread-based Architecture

• Process is an independent piece of code with its own memory space

• Thread is spawned by a process and works within the parents memory space

• Advantages of using Threads:

– Reduced overhead in context switching and reduction in overall memory requirements

– Microsoft fibers are light-weight threads further reduces context switching overheads by running purely in user mode

• Oracle uses processes in Unix and Threads in Windows

• Both Oracle and SQL Server use threads and optionally fibers. Threads/fibers are scheduled onto a CPU by a user mode Scheduler(UMS)

• Process/thread can be tied to processors in both Oracle (Windows) and SQL Server 2005 using CPU affinity feature.


Background Processes

OptionalMS DTCRECORecoverer

MandatoryLazywriterDBWnDB Writers

MandatoryDatabase

Checkpoint

CKPTCheckpoint

Processes

MandatoryLog WriterLGWRLogwriter

MandatoryDatabase

Cleanups and

Shrinking

SMONSystem

Monitor

MandatorySQLOSPMONProcess

monitor

requiredSQL Server Oracle IDOracle

Processes


Background Processes

N/AN/AARCnArchive

MandatoryNetworker Threads

DnnnDispatcher

MandatoryWorker Threads

SnnnShared Servers

OptionalWorker Threads

PnnnParallel Slave processes

MandatorySQL AgentJnnnJob Queue Process

requiredSQL Server Oracle IDOracle Processes

Database Locking

• MSSQL – Prior to SQLSERVER 2005– Select statements obtain shared locks on

pages/rows.• Prevents other statements from obtaining an exclusive

lock on those pages/rows.

• All Update statements require exclusive lock.

• These locks will lock all update transactions until the select commits or roll backs.

• transactions are physically serialized whenever 1 transaction selects the data and 1 changes.

• ORACLE –– Readers don’t block writers and writers don’t

block readers.

Database Locking – Row Vs Page

• MSSQL

– Prior to MSSQL 2005 no row level locking

– Does page level locking, which blocks all rows on

the page.

– MSSQL2005 – does a form of row level locking.

– MSSQL2005 – Escalates locks at row level to

page level automatically.

• ORACLE

– Row level locking

– Only one row is locked when DML is changing the

row.

Data Objects

Clustered IndexIndexed-Organized Table

Table VariableObject Table

** Linked Server FeatureExternal Table

Temporary TableTemporary Table

N/ANested Table

N/APartitioned Table

N/AClustered Table

HeapHeap-Organized Table

SQL ServerOracle

Data Objects - Table

• Heap is the default Form of data organization in a table, where data is stored in an unordered manner

• In Oracle, Index Organized Tables store data in a B-Tree structure in primary key order.

• SQL Server offers clustered indexes where data can be ordered by any column

• Oracle and MSSQL offer local and global temporary tables to store transient application data

Data Objects – Indexes (Diff)

NoYesBitmap Join

NoYesBitmap

NoYesB-Tree Partition

Yes (Clustered)YesB-Tree IOT

NoYesB-Tree Function Based

NoYesB-Tree Key Compressed

NoYesB-Tree Reverse

Yes (16 Cols)Yes (32 Cols)B-tree Composite

MSSQLOracleIndex Scheme

Data Objects – Views (Diff)

YesNoIndexed Views

NoYesObject Views

MSSQLOracleView Type

INLINE Views – MSSQL use Derived tables and CTE

(Common table Expressions)

Updateable Views – Restrictions in MSSQL can be bypassed by defining a “INSTEAD OF” trigger on the

view.

Data Types – Character Based

2GBImage 4GBBLOB

2GBNText4GBNCLOB

2GBText4GBCLOB

2GBText1 – 2GbLONG

1 - 8000Nvarchar1 – 4000NVarchar2

1 - 8000Varchar1 – 4000Varchar2

1 - 8000NVarchar1 – 4000NVarchar

1 - 8000Varchar1 – 4000Varchar

1 – 4000NChar1 – 2000NChar

1 - 8000Char1 – 2000Char

SQL SizeSQL TypeOracle SizeOracle Type

Data Types – Numeric Data

Small MoneyNumber(10,4)

MoneyNumber(19,4)

BitNumber(1)

FloatFloat / Number(38)

Numeric(p,s)Number(p,0)

decimalNumber(p,0)

tinyintNumber(3,0)

smallintSmallint /

Number(6,0)

intInt / Number(10,0)

BigintNumber(19,0)

SQL TypeOracle Type

Data Types – Other Types

FLOATREAL

FLOATFLOAT

VARBINARY(n)RAW(n) / BLOB

Binary(n)RAW(n) / BLOB

datetimeTimestamp

SmalldatetimeDate

datetimeDate

SQL TypeOracle Type

Date Data Types

• MSSQL datetime accurate up to 3.33 Milliseconds.

• Oracle “date” is accurate up to 1 second.

• Oracle’s timestamp up to 1 Millisecond.

• MSSQL “smalldatetime” up to 1 Minute.

• If application requires sub second Date Precision use Oracle’s “timestamp”.

• MSSQL “timestamp” not related to “datetime”

– MSSQL2005 – “timestamp” = SQL2000 –

“rowversion.

– It's a unique value which is changed every time

the row is updated

Data Access – DML and Examples

Select * from table where rownum <=5

Select top 5 from table

Select lastname||’,’||firstname from …

Select lastname +’,’+firstname from ….

Select lastname “Last Name”from …. Or

Select lastname as ‘last name’from ….

Select ‘last Name’=lastname from ….

Select sqrt(100) from dualSelect sqrt(100)

Semi Colon (;)GO

OracleMSSQL

Data Access – DML and examples

n/a – procedure to emulate the sp_rename function.

Sp_rename

Create or replace procedureCreate procedure

Select 3+5 from dualSelect 3+5 (from not required)

Select sysdate from dualSelect getdate()

Case or decodeCase

NVL(exp,val)ISNULL(EXP,VAL)

caseNullif(exp,exp)

Where ta.col(+) = tb.colLeft outer Join

OracleMSSQL

Select clause Differences

• MSSQL

– “TOP”

– “IDENTITYCOL”

– “ROWGUIDCOL”

– Column Alias – select c1 = ‘alias’ from t1

• ORACLE

– Select c1 from t1 where rownum < n

– Doesn’t support “identitycol”

– Doesn’t support “rowguidcol” (sys_guid)

– Column alias – select c1 “alias’ from t1

Update Statements

• MSSQL

– Supports a “FROM” clause

– MSSQL Example:

• Update t1 set col1=0 from t1=a, t2=b where a.c2 = b.c2

• ORACLE

– Doesn’t Support a “FROM” clause

– Oracle Example:

• Update t1 set col1=0 where col1 in (select col1 from t2 where c3 = ‘USA’)

Delete Statements

• MSSQL

– Supports a “FROM” clause

– MSSQL Example:

• Delete tableA from tableA a, tableB b where a.c1 = b.c1

• ORACLE

– Doesn’t Support a “FROM” clause

– Oracle Example:

• Delete tableA a

• Where exists (select * from tableB b where a.c1 = b.c1)

“Into” Clause

• MSSQL

– Select * into t1 from t2

– Insert * into t1 from t2

• ORACLE

– Create table t1 as select * from t2

– Insert into t1 as select * from t2

Global Tables Examples

• MSSQL

Create table #a_temp_table (col1 INT, col2 char(1))

• OracleCreate global temporary table

tt_a_temp_table (col1 number(6), col2 char(1))

On commit reserve rows

Empty String Literals

• MSSQL – interprets empty string as a single

blank space

• Oracle – interprets empty string as NULL

• MSSQL

– Insert into table (c1, c2) values (‘foo’,’’)

– Select c1 from table where c1 = ‘’

• Oracle

– Insert into table (c1,c2) values ‘foo’, ‘ ‘)

– Select c1 from table where c1 = ‘ ‘

Remote Objects

• MSSQL– Server_name.database_name.object_owner.object_name

– Example:

• Sqlserver1.sales.ny.acme.com.scott.emp

• ORACLE– Object_owner.object_name@database_name

– Example

• [email protected]

Operators

>=all>=ALL or !<allGreater than or equal

to every member of the

set

<=all<=ALL or !>allLess than or equal to

every member of the

set

=SOME or ININ or =ANYEqual to a member of a

set

Like ‘a%’

or LIKE ‘a\%’

Like ‘a%’ or LIKE’a[x-z]’Pattern matches

>=>= or !<Greater than or equal

to

<=<= or !>Less than or equal to

OracleMSSQLOperator

Functions

USERSESSION_USER

CASENULLIF

NVLISNULL

N/AIsdate

Userenv(‘host’)Host_name

Userenv(‘terminal’)Host_id

LengthDatalength

userCurrent_user

sysdateCurrent_timestamp

OracleMSSQL

STRING Functions

N/AUNICODE

TO_CHARStr

RPAD(‘ ‘,’N-1,’ ‘)SPACE(N)

SUBSTR(STR,-(N))REPLICATE(STR,)

N/ANCHAR

LTRIMLTRIM

SUBSTR(STR,1,N)LEFT(STR,N)

INSTRCHARINDEX

CHRCHAR

OracleMSSQL

Easy T-SQL example - MSSQL

Create proc proc1

As

Begin

Declare @x int

If exists (select * from table2)

Select @x = -1

end

Easy T-SQL example - ORACLE

Create or replace procedure proc1

As

V_x number(10);

V_temp number(1,0) := 0;

Begin

Select 1 into v_temp

From dual

where exists (select * from table2);

If v_temp = 1 then

V_x := -1;

End if;

End;

T/SQL – Example - MSSQL

UPDATE admin_role SET template ='<?xml version="1.0" encoding="UTF-8"?><templates>

<package id="identity"><action name="read"></action>

</package><package id="metadata">

<action name="read"></action></package><package id="ecommerce">

<action name="access"></action></package><package id="redirect">

<action name="read"></action><action name="change"></action><action name="create"></action><action name="delete"></action>

</package>…. **** Greater than 4000 Bytes<backstage action="adminBackstage-setPriority" area="6"></backstage>

<backstage action="adminBackstage-changeSubjHeading" area="6"></backstage></templates>'

WHERE name = 'Publisher Super Admin'

T/SQL Conversion Example - Oracle

declare

template_lob2 clob;

begin

template_lob2 :='<?xml version="1.0" encoding="UTF-8"?>

<templates>

<package id="identity">

<action name="read"></action>

<action name="change"></action>

<action name="create"></action>

<action name="delete"></action>

<action name="changepwd"></action>

<action name="settings"></action>

<action name="impersonate"/>

</package>…….*** Greater than 4000 Bytes

<backstage action="adminBackstage-changeSubjHeading" area="6"></backstage>

</templates>';

UPDATE admin_role set template=template_lob2 WHERE name = 'Publisher Super Admin';

Case example - MSSQL

update PUBLICATION

set Area = (select CASE

WHEN Area LIKE '00000000%' THEN 0









END

from PUB_AREA_STR_BACKUP

where PUBLICATION.pubid = PUB_AREA_STR_BACKUP.pubid)

where pubid in (select pubid from PUB_AREA_STR_BACKUP);

Case example - Oracle

update PUBLICATION set Area =

(select decode(Area, '0000000000000000', 0,

'0000000100000000', 1,

'0000001000000000', 2,

'0000100000000000', 8,

'0001000000000000', 16,

'0010000000000000', 32)

from article_meta where article_meta.articleid = PUBLICATION.PubId)

where exists (select articleId from article_meta where PUBLICATION.pubid = article_meta.articleid and area is not null and area <> '0000010000000000');

Sequence Differences

• MSSQL

– No Database Sequences

– Example –

CREATE TABLE SEQ_OFFERID_SEQ ( idvalue bigint IDENTITY(1,1) )

• T-SQL Example:declare @uid bigint

exec nextval2 'UserID_SEQ', @uid output

insert into change_record (userid, createupdatedate, action, sessionid, userid)

values (@uid, getdate(), 0, -1, -1)

Miscellaneous

MSSQL sp_rename functionif exists(select * from sysobjects where name =

'SEQ_ECOMM2_CONTRACTTERM' and uid=user_id())

exec sp_rename 'SEQ_ECOMM2_CONTRACTTERM', 'SEQ_ECOMM2_CONTRACTTERM_SEQ';

exec sp_rename 'Publication.IsRegistered', 'IsDoiRegistered', 'COLUMN';

ORACLE sp_rename equivalent

no oracle “sp_rename” equivalent – must use PL/SQL, or alter table.

VIEWS

• MSSQL doesn’t have create or replace view – so they drop first than create

CAST / Concatenation Diff

• Oracle

– UPDATE ad_data SET description = 'Ad '||

CAST(adId AS VARCHAR2(19)) WHERE description IS NULL;

• MSSQL

– UPDATE ad_data SET description = 'Ad ' + CAST(adId AS VARCHAR) WHERE description IS

NULL

References

• Migrating Applications from Microsoft SQL

Server to Oracle 9i Database

– Oracle White Paper

– November 2003

• Microsoft SQL Server and Oracle Compared

– Download.oracle.com/docs/

• Microsoft SQLServer 2005 for the

experienced Oracle Database Administrator

– Microsoft Course 7033A

Items Learned in this Session

• Basic differences between Oracle and MSSQL

– Database, Instance, Memory and Storage

Architecture

– Terminology

• Database locks

• Data Objects

• Data Types

• DML Examples

Thank You for Attending

Thank you,

Questions?

[email protected]

Please fill out your evaluation form.

Migrating SQL Server 2005 Applications to Oracle

Mike Gangler

Paper # 2086

2008 2086 gangler

Documents

oracle database

oracle schema

oracle shop

oracle dbas

codingto oracle

mssql extent oracle

mssql heapindex oracle

block mssql