How to use Oracle Database XML DB feature to store XML data as Object-Relational data.

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Using database Object-Relational storage for storing
and manipulating XML data in an integration project
Welcome to the Tour

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Oracle SOA/ESB common database problems
• Store large ammounts of XML data in database
• Picewise update of different XML complex types in database
• No direct support from SOA/ESB platform to save or read XML data from database
• Different database storage models for XML related data. Which to chose?
• Oracle database XML DB extension
About SYSCO

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Read and write XML data to database
• Relational model
– One table for each XML complex type
• XMLType view
– Efficient in one direction
• Storing XML data directly
– CLOB
– Binary XML
– Object-Relational storage

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Storing XML data in prepared database schema
• Huge task for database designer
– One table for each XML complex type
• Familiarity with reading and understanding XML schema document by
database designer.
– Compatibility and constraints
• A lot of database relations
– Primary to foreign key relationships

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Excerpt from WorkOrder.xsd XML Schema

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E-R diagram produced from complex XML Schema
file

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Relational database model problems
• Complex XML Schema = complex database model
– Substantial time to prepare
– Data type translation (string to varchar2 limitation)
• Many atomic XA database transactions.
– A lot of ESB Business Services or SOA partner links
– The whole transaction logic handled by SOA/ESB layer
– A lot of XPath expressions and transformations

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What is XML DB?
• XML DB Introduction
• XML DB Advantages
• XMLType view
• XML DB storage options
• SOA access to XML DB
• Object-Relational storage

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XML DB Introduction
By leveraging Object Types, Oracle has added to standard relational database
XML processing support. For that the special Object Type has been used:
XMLType.
Around XMLType Oracle has created whole stack of technology add-ons to
support XMLType data processing.

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XML DB Introduction
Important XML DB technology additions to Oracle database:
1. XMLType data type,
2. XML DB repository,
3. CLOB mapping,
4. XML Binary mapping,
5. Object-Relational storage,
6. Relationships,
7. Indexing,
8. XMLType views,
9. Relational view from XMLType data
10. XQuery support,
11. XML Schema validation
12. XML Schema extension,
13. DOM fidelity,
14. Etc.

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XML DB advantages
Advantages of using XML DB for storing and manipulating XML data:
1. Faster than many native XML databases (Object-relational storage, Relationships,
Indexing)
2. XML Schema validation,
3. Conversion from XML to relational data and back,
4. Virtual, versioned file system support,
5. Multiple protocol support for data exchange,
6. Read-Write one transaction support for whole XML document,
7. XML Piecewise update based on XPath expressions,
8. Relational data database Views based on XPath/XQuery expressions,
9. Support for updates of XML from relational views by using Instead Of triggers and
XQuery expressions.

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Using XMLType view
• Better performance
– Whole XML inserted in one transaction
– SQL: INSERT, UPDATE and DELETE operations accept whole XML document

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SQL: INSERT, UPDATE and DELETE operations on XMLType
object.

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Using XMLType view
• Preparation steps
1. Create XMLType View
2. Create PL/SQL wrapper faction, that will convert XML data from database
large string format (CLOB) to XMLType format
3. Create INSTEAD OF trigger attached to the XMLType view that will perform
actual update of database data stored in relational tables

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XMLType view example

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INSTEAD OF trigger attached to the XMLType View example

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Using XMLType view
• Disadvantages:
1. Still requires classic relational storage for storing XML data
2. The INSTEAD OF trigger attached to the XMLType view is considerably big and
has to contain more or less the same XPath expressions that we would
otherwise had to add inside Enterprise Service Buss Pipeline or inside SOA
BPEL process

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Using XML DB storage options for storing XML data
• XML DB various storage options:
– CLOB
– Binary XML
– XML DB Repository
– Object-Relational

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Using XML DB storage options for storing XML data
• CLOB storage option advantages:
– Simple to prepare (single database table for whole XML)
– Simple to implement
• CLOB storage option disadvantages:
– Space occupation
– For every update, insert or delete on any XML element, the whole XML
document needs to be rewritten
– Only text based indexing

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Using XML DB storage options for storing XML data
• Binary XML storage option advantages:
– Simple to prepare (single database table for whole XML)
– Simple to implement
– Better space occupation
– Better indexing options
– Faster than Object-Relational storage for whole XML inserts/updates
• Binary XML storage option disadvantages:
– Piecewise update
– Lack of BTree indexes
– More complex XPath for creating relational type views out of the nested XML
Schema complex types

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Using XML DB storage options for storing XML data
• Object-Relational storage option advantages:
– Storage optimization
– Better indexing options
– Fast for XML piecewise updates
– Various indexing options
– Schema validation
– XML DOM fidelity
– Check and unique constraints
– Automatic relationships generation
– Simpler for creating relational table views on nested XML Schema complex types
• Object-Relational storage option disadvantages:
– Slower than Binary XML for whole XML insert/update operations
– Potential dead locking in RAC environment during the update operations

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SOA access to XML DB
Why XML DB with SOA?
1. Single transaction for Read and Write whole SOAP/REST XML,
2. Just one “Exposed Service” creation,
3. No need to prepare classic relational schema,
4. Speed and simplicity!

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SOA access to XML DB
SOA support for XML DB?
1. No native support,
2. Some preparation steps,
3. PL/SQL knowledge requirement.

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Using Object-Relational storage for storing XML data How-To
XML Schema
Registration
Upgrade XML Schema
with XML DB annotations
Stored
procedure
Create stored procedure
to enable one
transaction support
DB Adapter
Prepare DB adapter to
use stored procedure
XQuery
mapping
Prepare XQuery
mapping to map XML to
stored procedure
parameter
DB Views
Create DB View to
expose XML data as
relational

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Upgrade XML Schema with XML DB annotations

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Registering XML Schema

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Object-Relational storage perspective
• XML Schema registration procedure creates and registers all database
objects for storing XML data.
– Every XML complex type becomes one XMLType table
– For every XML complex type one Object Type is generated that validates XML
data against XML schema and can be tuned
• Object-Relational storage is still of XMLType and has to be treated as such
– To access data as relational prepare views with XQuery syntax
– INSTEAD OF trigger that will use XQuery syntax to modify underlying XMLType
table

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Database view with XQuery syntax to extract XMLType data

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Database procedure for storing XML data

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Database procedure for reading XML data

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Configuring database JCA adapter

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Graphical representation of XQuery mapper file that maps XML to
string

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XQuery mapper code that maps XML to string

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Assembling final application

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Test pipeline

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Conclusion
Go for it!
1. Best option for storing large XML files with the need to perform piecewise XML
insert, update, delete
2. PL/SQL knowledge requirement for executing preparation steps
3. Most of preparation steps is one time job applicable to different projects
4. Full XQuery support
5. User friendly for integration developers

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Have a nice and inspirational day!
SYSCO 2016