The query language processor is activated on the simple search entry when the search mode selector is set to Query Language.
Here follows a sample request that we are going to explain:
mime:message/rfc822 author:"john doe" Beatles OR Lennon Live OR Unplugged -potatoes
This would search for all email messages with John Doe appearing as a phrase in the From: header, and containing either beatles or lennon and either live or unplugged but not potatoes.
The first element, mime:message/rfc822 is a special switch that restricts the results to be email messages. There could be several such switches, which would form a list of allowed types.
The second element author:"john doe" is a phrase search limited to a specific field. Phrase searches are specified as usual by enclosing the words in double quotes. The field specification appears before the colon. Recoll currently manages the following fields:
title, subject or caption are synonyms which specify data to be searched for in the document title or subject.
author or from for searching the documents originators.
keyword for searching the document specified keywords (few documents actually have any).
The query language is currently the only way to use the Recoll field search capability.
All elements in the search entry are normally combined with an implicit AND. It is possible to specify that elements be OR'ed instead, as in Beatles OR Lennon. The OR must be entered literally (capitals), and it has priority over the AND associations: word1 word2 OR word3 means word1 AND (word2 OR word3) not (word1 AND word2) OR word3. Do not enter explicit parenthesis, they are not supported for now.
An entry preceded by a - specifies a term that should not appear.
Words inside phrases and capitalized words are not stem-expanded. Wildcards may be used anywhere.
You can use the show query link at the top of the result list to check the exact query which was finally executed by Xapian.