query

query = [ term ] , { { space } , term } ;

query is referencing:

term
space

The empty query returns all documents of the collection.

term

term = 
  ( "ɛ" (* should term *)
  | "+" (* must term *)
  | "-" (* must not term *)
  ) , [ qualifier , ":" ] ,
  ( word
  | '"' , word , { space , word } , '"' , (* phrase *) [ "~" ,
    slop (* distance *) ] ,
    [ "+" , boost (* factor *) ]
  ) ;

Items referencing term:

query

term is referencing:

qualifier
word
space
slop
boost

ɛ denotes the empty symbol (so, no prefix operator given).

wildcard is a prefix search.

If you specify only '*', then you mean all possible values (use with care, best used with a qualifier with keyword indexing!)

For phrases you can specify a distance within the query should match (the slop, measured in words) and a boost factor in the query (a floating point number).

For phrases we also don't stem, normalize or search for prefixes in any way (but for minor normalizations in order to allow for case-insensitive matching).

qualifier

qualifier = ? qualifier ? ;

Items referencing qualifier:

term

word

word = ? word ? ;

Items referencing word:

term

space

space = ? space ? ;

Items referencing space:

query
term