Querying Heterogeneous Sources

Problem: Different syntax, features, schemas.

Example: Title contains distributed AND database (W) system

• For Dialog:

  SELECT (distributed AND database (W) system) / TI (Equivalent)
  

• For AltaVista:

  • title: (distributed AND database NEAR system) (Subsuming Query)
  • Title contains database (W) system (Filter Query)

Query Trans

Post-Filter

Source

Q

A

QS

F

AS

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