CoopIS, Trento, Italy, 05/09/2001 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 Henrike Berthold

Problem Application 1 Application n SDBS 1 SDBS k 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 Henrike Berthold

Media retrieval systems 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 Henrike Berthold

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) Henrike Berthold

A Federated Multimedia Database System Application 1 Application n SDBS 1 SDBS k MRS 1 MRS m MSS 1 MSS n FMDBMS FMDBS - Database schema and query processing - Operations on media objects - Transactions Henrike Berthold

Global schema construction 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) integrates Media Schema (MS) SDBS1-Schema SDBSk-Schema MSS1-Schema MSSn-Schema Henrike Berthold

Example media schema Common data model: ODMG, CROQUE Types and subtype-relation Classes and subclass-relation :TSingleMedia :TObject Video:TVideo Audio:TAudio Text:TText ContMedia:TContMedia Image:TImage CityPart:TImagePart PassportPhoto:TImage City:TImageWithPart 1 * Henrike Berthold

Step 1: Base integration Schema architecture: MSS1-Schema MSSn-Schema Media Schema (MS) SDBS1-Schema SDBSk-Schema Structured-data Schema (SDS) integrates Global Schema Henrike Berthold

Step 2: Integration of media retrieval functions single: objekt method + coll: class method -, function - allows combination of boolean queries with media retrieval queries Henrike Berthold

Step 2: Example c2:t1 c3:t2 c1:t1 c6:t4 c7:t3 c5:t3 c4:t3 t2 t0 t1 t3 Henrike Berthold

Step 3: Extension Simple extension: relationships complex extension: new objects + relationships TVisualElement Time interval Region TVideoElement TTextElement TImageElement TVideo TText TSingleMedia TLecture TSlide TImage 1 1..* 2 8 x y Region for video image Region for text t in min Text1 Image1 Video Image2 Text2 Henrike Berthold

Schema architecture Global Schema Structured-data Schema Media Schema Internal Schema integrates SDBS1-Schema SDBSk-Schema MSS1-Schema MSSn-Schema MRS1-Function MRSm-Function Henrike Berthold

Construction data Henrike Berthold

Query processing Henrike Berthold

FMDBS-specific problems Modification Vertical fragmentation GT3 GT4 GT1 GT2 complete replacement of a global object is not possible Replacement of search methods Henrike Berthold

Comprehension syntax Henrike Berthold

Monads and algebras Henrike Berthold

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 Henrike Berthold

Modification Henrike Berthold

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 Henrike Berthold

Replacement of function single by coll Henrike Berthold

Identification of a lower bound Henrike Berthold

Identification of a subcollection restriction Henrike Berthold

Prototype Henrike Berthold

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 Henrike Berthold

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 Henrike Berthold