So final question, what should I do to make that index much smaller on the disc.
Tune your penalty and picksplit function. Gevel module can help you to look inside of index ( http://www.sai.msu.su/~megera/postgres/gist/gevel ).
Usially, index becomes big when picksplit works bad: during split it place one key on one page and all other keys on another page. So you have a huge number of page with single value.
-- Teodor Sigaev E-mail: [EMAIL PROTECTED] WWW: http://www.sigaev.ru/ ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings