Chap 10' Strudel

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2000.8.31 ? ? ?
Chap 9. The Lore System
Chap 10. Strudel
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Developing a database management system for
semi-structured data
1. An application on top of existing relational
and object database systems( poor
performance because of inappropriate
clustering)() 2. Using a low-level object
server such as Exodus. 3. Building the system
from scratch()
() Ozone () Lore
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Lore Architecture
Textual Interface
HTML GUI
Application
API
results
Nonquery requests
query
parsing
pre- processing
query plan generator
query optimizer
object manager
query operations
utilities
external data manager
physical storage
external read-only data sources
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Query processing and Indexes
Vindex(value index) takes a label l, a
comparator, and a value returns all atomic
objects satisfying the condition with an
incoming l-edge Btrees Lindex(link
index) takes an oid o, and a label l returns
all (parent) objects having an l-edge going to
o linear hashing Bindex takes a label
l returns all pairs of objects connected by l
full-text index takes a string s returns all
text objects containing s Pindex(path
index) takes an object o, and a path expression
p returns all the objects reachable from o by
following p
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The Traversal of the OEM graph
Forward Using the stored description of an
object, get to its sub-objects Backward Using
the Lindex, get to its parent objects
db
select X from db.a.b X where X.c 5
a
b
10,000
Vindexes Lindexes
500 per each a-edge
c
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Other aspects of Lore(1)
The Data guide For uses to explore the structure
of the database and formulate queries For
system to store data statistics Managing
External Data The integration of data from
heterogeneous info sources Proximity Search eg.
movie Cage Travolta Views select X from
db.movies X where X.director Hitchcock with
title, actor, actor.name, actor.picture, script,

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Other aspects of Lore(2)
Dynamic OEM and Chorel OEM Temporal database
DOEM Lorel Chorel(Change-Lorel)
select X from db. lt added T gt movies X where
X.director.country in db.South-America.country
and T gt 1990/06/12
Mixing Structured and Semi-structured in Ozone a
system for OEM management on top of an object
database system, O2 system
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Strudel Web Site Construction

• Managing the information presented at the site
• Managing the structure of the Web site
• Creating the graphical presentation of the HTML
  pages
• Strudel separates these three Web site creation
  tasks
• data management, structure management, graphical
  presentation

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Strudel Architecture
graphical presentation
structure management
data management
Struc- tured files
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Strudel Data Management and Structure Management
Fig 10.7
Fig 10.8 sitegraph.st
input
datagraph.ddl
Fig 10.6 integrate.st
Bibentry
Fig 10.5 bibtex.ddl
Struc- tured files
Fig 10.3 bibtex.bib
Fig 10.4 people.ddl
user
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Strudel Management of the Graphical Presentation

• ltSFMTgt
• ltSFORgt an iterator
• ltSIFgt a conditional statement

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Advantages of Declarative Web Site Design

• We can define multiple views of the Web site with
  minimal effort, either by writing a new query or
  by changing the HTML templates(eg. personalized
  Web sites)
• The clear separation of the three web creation
  tasks
• Maintenance
• Once a Web site has an underlying data model, it
  is possible to query and transform it in a
  declarative fashion