This document discusses optimizing XML performance in Oracle databases. It covers topics like choosing an XMLType storage model, using XML indexes, avoiding impedance mismatch between XML and relational models, and best practices for XML schema and data design. The goal is to provide fast DML operations on XML data through techniques like leveraging the relational engine, minimizing parsing overhead, and avoiding unnecessary validation. A demonstration shows how to use XDB utilities and annotations to optimize physical XML storage and access.

1. XML Programming in PL/SQL (Part 2) “Exploring Oracle XML Features in Depth” Marco Gralike

2. Agenda

5. Agenda

6. “The foundation is there; So why not use it?” …referring to the Relational Model… Chris Date- Hotsos keynote, 2009

7. Relational…

8. XML…?

9. Evolution…

10. If you’re a performance nerd, this is actually cool… No one figured out XML yet… Solving the customer problem… Back to basics… Deeper understanding of the data handling issues… So why the “….” XML…?

11. Agenda

12. Free Format…”XML is cool”… (aka no design effort) Have to Uphold the “Coding Granny Argument”… Everyone for themselves… Waiting for “Codd, Date”… Square wheels… What’s spoiling the soup…?

13. Different data models XPath models an XML document as a tree while most general purpose programming languages have no native data types for a tree. Different programming paradigms XSLT is a functional language, while Java is object-oriented and Perl is a procedural one. Impedance Mismatch

14. Effects, Costs Unnecessary CPU and Memory Overhead A lot of expensive type and encoding conversions Impedance Mismatch

15. Agenda

21. Containerization

22. The “Dimensions” in 1 XML doc. 1 3 4 5 2 X Y 6 Z nx rows Elements with maxoccurs=“unbounded”

23. Multi Dimensional Issues… Its a database… Its Row based Its Column based Its multiple databases… More then 1 XML doc Not uncommon 1 Mb >>

24. Complexities of a database “Relations” “Redundancy” “Nullology” Design, etc… It can contain a database 10 Mb or bigger nowadays More often than less… Enormous complex XSD’s XMLType – Not just a “Container”

25. Checked on XML Well-Formedness One root element Begin & End tags If XML Schema reference XOB methods will be used if an XML Schema is available DOM methods will be used if registered XML Schema information is not available XMLType – Not just a “Datatype”

26. What you want in access… Fast DDL Selects Inserts, Deletes, Updates Specific / Smart Small XML Fragments Direct Access

27. Mistakes are very, very Painful! Inserts, Updates & Deletes Fast Efficient Selects Precise Via Indexes ? XML Validation Strict, Lazy, really needed ? Client Side Possibilities

28. Agenda

29. Oracle XMLType “Containers”

30. XOB DOM XMLType Memory

31. Object Relational Binary CLOB XMLType

32. Physical Design Logical Design XMLType Solutions

33. Document contra Data Driven

34. Structured / Semi-Structured Structured Semi Structured

35. Common XML Parsers Often DOM or Infoset based CPU intensive Memory intensive Serializing, parsing, tree traversals, happen in memory…

36. In Memory: Common XML Parsers Often handle XML tree traversals only via ONEmethod It is not structured, semi-structured or unstructured XML content aware It is not very “smart” / “content aware” regarding XMLhandling based on its XML tree’s and/or XML data content

37. XMLType Physical Storage CLOB LOB LOB index Object Relational Varray, Types, Nested Tables IOT, B-Tree, XML Schema Binary XML LOB, LOB Index Stored in Post Parse Representation

38. Hybrid CLOB Mixed complex[n] un/structured XSD [y] B-Tree, IOT Document na unstructured XSD [n] XMLIndex Relational World XMLDB World XML Data Storage XMLType column/tables XMLType Views Obj.Rel. Binary XML Content complex[n] structured XSD [y] B-Tree, IOT (Object) Relational Objects Mixed complex[y] un/structured XSD [y/n] XMLIndex Relational Tables

39. Choosing a Storage Model

40. Agenda

41. Index Quick Sheet

42. Unstructured XMLIndex (UXI), 11.1 PathTable UsePath Subsetting FullBlown XMLIndex canbe BIG Token Tables (XDB.X$......) Query re-writeonTokens Fuzzy Searches, // Optimizer Statistics CanbemaintainedManually Recorded inPending Table Secondairyindexespossible Unstructured XMLIndex f (x) Path Table

43. Structured XMLIndex (SXI), 11.2 Content Table(s) BasedonXMLTABLE syntax XMLTable construct canbe nestedbut: Only 1 extra XMLType allowed VIRTUAL column is passed CanbemaintainedManually Secondairyindexespossible Structured XMLIndex f (x) Content Tables

44. Driving access on CONTENT BTree Index bookstore Secondary Oracle Text Index Function based Index (XPath) B-Tree Index book whitepaper StructuredXMLIndex Unstructured XMLIndex title author author chapter title author id paragraph content structured content

45. There can be only one XMLIndex…

46. Agenda

47. Design

48. XML Schema will be parsed only once XML Schema will be cached in memory (SGA) No additional parsing No additional validation XML Schema registration doesn’t have to be creating types/tables… Binary XML has part of the solution XML Schema Advantages

49. XML Document structure is known, therefore No parsing is needed when loaded from disk into memory XML OBject (XOB) structures can be applied Memory footprint is much less compared to DOM structure Needed specific nodes can now be handled efficiently in memory XML Schema Advantages

50. XDB Annotations Hybrid: CLOB withinOR

51. XDB Annotations (OR/Binary XML) Levels Root, Simpletype, Complextype xmlns:xdb="http://xmlns.oracle.com/xdb" xdb:storeVarrayAsTable xdb:defaultTable xdb:maintainDom xdb:maintainOrder xdb:SQLInline Oracle V.11.1.0.7.0 - Partitioning xdb:tableprops

52. Mixing Logical and Physical Design

53. XDB Utilities Toolset Object Relational Storage And a bit regarding Binary XML Makes xdb:annotation easy Helper Packages for index creation Whitepaper on “best practices” Not a Replacement for proper XML (Schema) Design

54. XML Schema - Query Rewrite String CHAR String Float bookstore CLOB VARCHAR2 (20) book whitepaper title author author chapter title author id paragraph NUMBER (15) content content

55. XML Design Avoid Cyclic References in XML Schemata For ease of Maintenance: xdb:annotations Is DOM validation, fidelity needed ? CPU / XML parsing: XML Schema validation “overhead” ? Index maintenance overhead, when using “disk” solutions Y X

56. Be aware of what you are doing ! Avoid unneeded (full) XML Schema validation During Storage (Inserts), Generating XML xdb:MaintainDOM=false Avoid Impedance mismatch Java  XML  Java  XML  Relational  XML  Java (“All In One Go Objective”) Avoid XML fragments // and/or via XMLEXISTS Use Indexes Y X

57. Agenda

58. Keep XML small Do not use / enforce Pretty Print if not needed Avoid namespace reference “Overkill” Most used Namespace is Leading Use short Namespace References Make XML data as “sparse” as possible <employee><name>Marco</name></employee> <employee name=“Marco”/> XML Data Partitioning Binary XML if needed Y X

59. Keep XML small (OR specific) Don’t use “meaning full element names” 64Kb DDL “create table” buffer ORA 01792 maximum number of columns in a table or view is 100 Break XML up Out of Line CLOB (unstructured) Not Accessed Data Don’t create objects if you don’t need it Use xdb:defaultTable=“” for global types

60. Holistic Approach & DEMO

61. Customer Use Case Memory / DOM Memory / DOM CLOB Oracle Advanced Queue XMLType BLOB Process Checks Validation XML Schema (JAVA) Store in ETL Tables Shred Elements Via XMLDOM

62. New XML Approach Rewrite on Disk / XOB (Relational) CLOB Oracle Advanced Queue BLOB Store in ETL Tables Oracle Workflow Validation Against XML Schema Checks XMLType Table (O.R)

63. Using the CBO as an XML Parser… ORA-31186 ORA-31186 ORA-31186 ORA-31186: Document contains too many nodes Cause: Unable to load the document because it has exceeded the maximum allocated number of DOM nodes.

64. Demonstration XDB Utilities JDeveloper XML Schema xdb:annotations Effect on Queries

65. Recap

66. Using the (XML) Relational Mindset Design XSD as you would with E(E)R Design for proper physical access, performance: Storage, Index Content Awareness Partitioning Overkill of “meaning full” data parsing Avoid Redundancy, whitespace, “Pretty Print” Design with the future in mind

67. So in short: Balanced Design Inserts, Updates & Deletes XML Future Changes Index Maintenance Selects In Memory Via Indexes XML Validation Strict, Lazy Client Side Possibilities

68. Reward Optimal performance Out performing standard XML solutions PL/SQL, SQL access optimized for best performance on XML PL/SQL, SQL, Design, Access: Efficient Fast

70. References (1) Oracle XML DB http://download.oracle.com/docs/cd/E11882_01/appdev.112/e16659/toc.htm XML DB OTN / FAQ Thread http://forums.oracle.com/forums/forum.jspa?forumID=34 http://forums.oracle.com/forums/thread.jspa?threadID=410714

71. References (2) Oracle Whitepapers Oracle XML DB : Choosing the Best XMLType Storage Option for Your Use Case (PDF) Oracle XML DB : Best Practices to Get Optimal Performance out of XML Queries (PDF) Blog http://technology.amis.nl/blog http://blog.gralike.com (Dedicated XMLDB blog)