Data Integrati。n Data integration Combines data from multiple sources into a coherent store Schema integration: e. g. A cust-id B cust-# Integrate metadata from different sources Entity identification problem: Identify real world entities from multiple data sources e.g. Bil Clinton= William Clinton Detecting and resolving data value conflicts For the same real world entity, attribute values from different sources are different Possible reasons: different representations different scales e g metric vs, british units 1212 Data Integration ◼ Data integration: ◼ Combines data from multiple sources into a coherent store ◼ Schema integration: e.g., A.cust-id  B.cust-# ◼ Integrate metadata from different sources ◼ Entity identification problem: ◼ Identify real world entities from multiple data sources, e.g., Bill Clinton = William Clinton ◼ Detecting and resolving data value conflicts ◼ For the same real world entity, attribute values from different sources are different ◼ Possible reasons: different representations, different scales, e.g., metric vs. British units