[Dovecot] Fts Search

Hello, i'm trying to search in mails which are in russian language. Search works fine for UTF-8 mails, but it ignores KOI8-R ones. For english in any mails it also works fine. How i can solve it? I have dovecot 1.2.17 and following config for fts: protocol imap { ..... mail_plugins = quota imap_quota autocreate fts fts_squat } plugin { ... fts = squat fts_squat = partial=4 full=10 }