As a followup to my own message:
On 5/8/15 1:34 PM, Robert L Mathews wrote:
I've noticed that when using Lucene full text search, most queries use the indexes and/or header cache and are fast [...] But an OR query that mixes headers and body does not use the available FTS indexes for the BODY part and is slow:
This turned out to be my own fault because of a foolish mistake I made when testing. Dovecot actually works fine on all the search queries I mentioned, even in version 2.1.7.
My apologies for the noise on the list.
(My mistake was that when switching from Squat to Lucene, I didn't remove a local patch that prevented FTS from being used for header searches, because I thought the patch was only affecting Squat. That patch was to workaround what I reported in <http://www.dovecot.org/list/dovecot/2014-May/096360.html>. But the patch also affected Lucene.)
-- Robert L Mathews, Tiger Technologies, http://www.tigertech.net/