Information Retrieval Systems Information retrieval(IR)systems use a simpler data model than database systems Information organized as a collection of documents Documents are unstructured,no schema Information retrieval locates relevant documents,on the basis of user input such as keywords or example documents ·e.g.,find documents containing the words“database systems” Can be used even on textual descriptions provided with non-textual data such as images Web search engines are the most familiar example of IR systems Database System Concepts-7th Edition 31.3 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 31.3 ©Silberschatz, Korth and Sudarshan th Edition Information Retrieval Systems ▪ Information retrieval (IR) systems use a simpler data model than database systems • Information organized as a collection of documents • Documents are unstructured, no schema ▪ Information retrieval locates relevant documents, on the basis of user input such as keywords or example documents • e.g., find documents containing the words “database systems” ▪ Can be used even on textual descriptions provided with non-textual data such as images ▪ Web search engines are the most familiar example of IR systems