Information Retrieval Systems (Cont.) Differences from database systems IR systems don't deal with transactional updates (including concurrency control and recovery) 。 Database systems deal with structured data,with schemas that define the data organization IR systems deal with some querying issues not generally addressed by database systems Approximate searching by keywords Ranking of retrieved answers by estimated degree of relevance Database System Concepts-7th Edition 31.4 ©Silberscha乜，Korth and SudarshanDatabase System Concepts - 7 31.4 ©Silberschatz, Korth and Sudarshan th Edition Information Retrieval Systems (Cont.) ▪ Differences from database systems • IR systems don’t deal with transactional updates (including concurrency control and recovery) • Database systems deal with structured data, with schemas that define the data organization • IR systems deal with some querying issues not generally addressed by database systems ▪ Approximate searching by keywords ▪ Ranking of retrieved answers by estimated degree of relevance