Text in Databases

Character String Retrieval
      Inverted Index
      Trie
      Return match location in string, and not just "record id"

Information Retrieval principles:
      Relevance
      Precision
      Recall

Queries are imprecise, but easy to specify.
      Boolean Model
      Scoring Models
      Cosine similarity
      TF/IDF

XML is a bridge
    CONTAINS in XQuery
    Leads to TexQuery

Design Goals of TexQuery
    Context, for query and for returned result
    Extensibility
    Scoring and Ranking (orthogonal to search!!)
    Arbitrary cross-embedding
FullMatch Data Model

Relaxations on Structure specification
    Keyword-based database search
    Schemafree XQuery