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The Detailed Query Syntax

A query consists of one or more query conditions. They can be connected with AND, OR or NOT. Leaving out the boolean connector means connecting with OR. The NOT connector takes the meaning of AND NOT.

                query -> or_expression or_operator query
                         or_expression query
        or_expression -> and_expression and_operator or_expression
                         and_expression not_operator or_expression

A query condition can be:

a parenthesed query
query conditions can be nested in arbitrary depth
a field expression
consists of a field specifier, a predicate and a comparison value/expression
a literal search expression
which can be denoted with ingle or double quotes
a proximity expression or an atleast expression
an index expression
consisting of an index predicate like soundex or phonix
a single term
a wildcard term
denoted with an asterisk (`*')
       and_expression -> `(' query `)'
                         `'' s_literal_expression `''
                         `"' d_literal_expression `"'

Boolean operators can be specified in various languages:

          or_operator -> `or'
         and_operator -> `and'
         not_operator -> `not'

The class s_character consists of all printable characters without the single quote itself (`''), analogous the class d_character consists of all printable characters without the single double quote itself (`"').

 s_literal_expression -> s_character s_literal_expression
 d_literal_expression -> d_character d_literal_expression

Proximity expressions consist of two operands (terms) and a proximity operator. The proximity operator consists of `w/' or `pre/' and a number denoting a word distance.

  • `nuclear w/10 waste' matches in a document if it contains the terms `nuclear' and `waste' within 10 words.
  • `nuclear pre/10 waste' matches in a document if it contains the term `nuclear' up to 10 words before the term `waste'.

num1 may be any natural number greater than zero.

 proximity_expression -> term `pre/' num1 term
                         term `w/' num1 term

Atleast expressions consist of one operand (term) and the atleast/ operator with a number denoting the minimum occurance frequency of the term in a matching document.

   atleast_expression -> `atleast/' num1 term

Various indextypes can be used as similarity predicates. They can be specified for single terms as well as for more complex query parts.

     index_expression -> indextype term
                         indextype_list { query }
       indextype_list -> indextype, indextype_list
            indextype -> indextype_text
       indextype_text -> `text'
    indextype_soundex -> `soundex'
     indextype_phonix -> `phonix'

A term consists of a list of characters (not including the characters `<', `>', `=', `(', `)', `{', `}', `/', `,' and any whitespace which are interpreted as word delimiters). A wildcard_term is a term followed by an asterisk (`*').

                 term -> char_list
        wildcard_term -> char_list `*'
            char_list -> character char_list

Field expressions are used to search within special fields. A non_field_expression is the same as query except that a field_expression mustn't occur.

     field_expression -> field num_predicate num_term
                         field `=' non_field_expression

A num_term is an integer or a real value. With numeric fields various comparison predicates can be used.

        num_predicate -> `<'

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