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CoopIS, Trento, Italy, 05/09/2001
DATABASES
Schema design and query processing in
a federated multimedia database system
Henrike Berthold & Klaus Meyer-Wegener
Dresden University of Technology, Germany
Problem
A Federated Multimedia Database System
Global schema construction
Query processing
Summary
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
DATABASES
Problem
Application 1
SDBS 1
SDBS k
Application n
MRS 1
MRS m
MSS 1
MSS n
• SDBS: Database system with a schema, a query language, ...
• MRS: Media retrieval system
• MSS: Media storage system
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
Media retrieval systems
DATABASES
• Perform content-based search based on automatically extracted
features (perception + semantical primitives)
• work for a set of media objects of a certain media type such as
image, text, video, audio or a subset with a certain semantics
such as passport photos
• Retrieval functions
– single: search argument (example, feature, weighting),
media object -> similarity value
– coll: search argument -> list if tuples (similarity value, MID)
– result restrictions of coll: lower bound for similarity values,
subset of media objects, top n
• Example systems: QBIC (IBM), Excalibur Image Datablade,
Melodiscov (LIP6)
• Problem: only interactive interface and no programming one
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
DATABASES
Media storage systems
•
•
•
•
•
Store and manage media objects like images, videos
provide operations for those
support especially timed playout of continuous media objects
all systems provide media description data such as size, format
some systems support transactional concepts like durability,
atomicity
• Example systems: Tiger Shark (IBM), Symphony (Uni Texas),
Fellini (Bell Labs), Kangaroo/Memo.REAL (Dresden University
of Technology)
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
A Federated Multimedia
Database System
DATABASES
Application 1
Application n
- Database schema and query processing
- Operations on media objects
- Transactions
FMDBMS
SDBS 1
SDBS k
MRS 1
MRS m
MSS 1
MSS n
FMDBS
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
Global schema construction
DATABASES
based on two intermediate schemas:
• Structured-data schema (SDS) = global schema of all
SDBS-Schemas
• Media schema (MS) = global schema of all MSS
schemas
Structured-data Schema (SDS)
Media Schema (MS)
integrates
SDBS1-Schema
SDBSk-Schema
DRESDEN UNIVERSITY OF TECHNOLOGY
MSS1-Schema
MSSn-Schema
Henrike Berthold
Example media schema
DATABASES
Common data model: ODMG, CROQUE
• Types and subtype-relation
• Classes and subclass-relation
:TSingleMedia
:TObject
ContMedia:TContMedia
Video:TVideo
Audio:TAudio
PassportPhoto:TImage
Image:TImage
City:TImageWithPart
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Text:TText
1
*
CityPart:TImagePart
Henrike Berthold
Step 1: Base integration
DATABASES
Schema architecture:
Global Schema
Structured-data Schema (SDS)
Media Schema (MS)
integrates
SDBS1-Schema
SDBSk-Schema
DRESDEN UNIVERSITY OF TECHNOLOGY
MSS1-Schema
MSSn-Schema
Henrike Berthold
Step 2: Integration of media
retrieval functions
DATABASES
• single: objekt method +
• coll: class method -, function -
• allows combination of boolean queries with media
retrieval queries
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
DATABASES
Step 2: Example
t0
t1
t3
c1:t1
c1:t5
t2
t4
t6 (=t3‘)
c4:t3
c11:t6
c5:t3
c12:t6
c2:t1
c3:t2
c6:t4
c13:t7
c7:t3
t5 (=t1‘)
t7 (=t4‘)
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
Step 3: Extension
DATABASES
• Simple extension: relationships
• complex extension: new objects
+ relationships
TLecture
1
1..*
TVisualElement
TSlide
TVideoElement
y
TSingleMedia
Time interval
Region
TVideo
TTextElement
TText
TImageElement
Region for
video
Region for
image
TImage
Video
Region for text
Image1
Image2
Text1
Text2
x
DRESDEN UNIVERSITY OF TECHNOLOGY
2
8
t in min
Henrike Berthold
DATABASES
Schema architecture
Global Schema
Structured-data Schema
Media Schema
Internal Schema
integrates
SDBS1-Schema
SDBSk-Schema
MRS1-Function
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MSS1-Schema
MSSn-Schema
MRSm-Function
Henrike Berthold
Construction data
DRESDEN UNIVERSITY OF TECHNOLOGY
DATABASES
Henrike Berthold
Query processing
Global OQL Query
Global query
computation
Modification
DATABASES
Type checking and
mapping to intermediate representation
Construction
data
Decomposition and
global optimization
Replacing global specifiers by local ones
Decomposition and optimization by the
global query processor
Local optimization
and execution
Optimization by the local query
processors and local execution
Global execution
Combining local results globally
Result
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
DATABASES
FMDBS-specific problems
• Modification
– Vertical fragmentation
GT3
GT1
GT2
GT4
complete replacement of a global object is not possible
– Replacement of search methods
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
Comprehension syntax
DRESDEN UNIVERSITY OF TECHNOLOGY
DATABASES
Henrike Berthold
Monads and algebras
DRESDEN UNIVERSITY OF TECHNOLOGY
DATABASES
Henrike Berthold
DATABASES
Advantages
• uniform representation of collections (set, bag, list)
and aggregations
• readability
• there are equivalences defined
– easy manipulation
• there is a mapping to an algebraic expression
– embedding in traditional query processing is possible
• thus: better suited for manipulations than an object
algebra
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
Modification
DRESDEN UNIVERSITY OF TECHNOLOGY
DATABASES
Henrike Berthold
DATABASES
Improvements
• Paths that belong to one source are replaced
completely;
so far: replacement of each single function
• A generator which binds a global object is replaced
by a sequence of qualifiers which produce all local
objects that are used in the query;
so far: production of local objects there, where they
are used
• exploit function coll and its result restrictions
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
Replacement of function
single by coll
DRESDEN UNIVERSITY OF TECHNOLOGY
DATABASES
Henrike Berthold
Identification of a lower
bound
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DATABASES
Henrike Berthold
Identification of a
subcollection restriction
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DATABASES
Henrike Berthold
Prototype
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DATABASES
Henrike Berthold
DATABASES
Summary
• An FMDBS manages structured data and media
data. It takes the integration efforts from the
applications.
• Development of a procedure to construct the global
schema
– data (relationships, new types and classes) and media
retrieval functions can be added
• Development of a procedure to modify queries
– can handle the vertical fragmentation
– choses efficiently executable media search functions
• Applications have a powerful mean to find suitable
data
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold
DATABASES
Outlook
• Problem: Chose a result restriction if some
are applicable
• Need of a general cost model of media
search systems
• Construction of a complete FMDBS
• Need of tools which support the construction
and the administration
DRESDEN UNIVERSITY OF TECHNOLOGY
Henrike Berthold