FOO BAR
the query is treated like
FOO or BAR
There are additional capabilities of the WAIS index:
PARTIALWORD == The asterisk symbol '*' is parsed if it immediately follows a word,
as an key to search for all partial words that match the first part of the
word. For example,
FOO*
would match FOO, FOOD, FOOBAR, ...
BOOLEANS == boolean 'and' and 'not' operators. For example,
FOO and BAR
would match files containing both FOO and BAR.
There are no nesting symbols. Words are evaluated from left to right in
the wais query string. When a 'not' operator is found, the following
single word is moved into a buffer of not-words. This not-word buffer
is evaluated after all the other words are evaluated. If a document matches
a not-word, that document is removed from the set of matches (given a
score of zero).
When an 'and' word is found, the word following it is checked for matches
to documents, and the the set of documents matching this and-word is
compared to the set of documents matching any words prior to the and-word.
The intersection of prior and current matching documents is retained, others
are removed (set to a zero score).
For example, this query
red and blue or yellow but not green and orange or black but not white
Will be interpreted like this (the parentheses just show the implicit left-to-right
interpretation):
(((((red and blue) or yellow) and orange) or black) not green) not white)
LITERAL == The quote or double-quote symbols are interpreted, if they occur
in pairs around a string, as requesting a literal match of the enclosed
string. Any special symbols, 'and', 'not', and '*' inside a literal string
are not interpreted. The first part of a literal string must be a
word that is indexed for that data, rather than a delimiter symbol, for
a match to be found. For example,
"FOO BAR"
would match files containing the string "foo bar".
These additional features can generally be mixed in a query, for example:
Query: 'Df(32)-[34]red' and hum* not Brown