Boolean parsers

The default, natural language, full-text search mode works well for inexperienced users who can simply describe what they want to find using plain English (or any other language) and let the system figure out, with complex statistical and probabilistic analysis, what rows are relevant to them. Other users want more control over what will be found. This is where Boolean search mode is used. It allows users to specify exactly which words must be present in all found rows and which words must not be present. It can search for "phrases"—sequences of words—for prefixes of words, and fine tune the importance of individual words for the result of a query. For Boolean search mode to work, the full-text parser needs to support it; it needs to be able to extract the Boolean search operators from a query and to convey this information to MySQL.

In our example from the previous chapter we ignored Boolean search mode and only sent the search words—not Boolean operators—from the query...