Re: tsearch2 on-demand dictionary loading & using functions in tsearch2

> * Considering the database is loaded separately for each session, does
> this also imply that each running backend has a separate dictionary
> stored in memory?

Yes.
>
> As for downsides, I only really see two:
> * Tracking updates of dictionaries - but it's reasonable to believe
> that new connections get open more often than the dictionary gets
> updated. Also, this might be easily solved by stat()-ing the dictionary
> file before starting up session, and only have the server reload it if
> there's a notified change.
> * Possibly complicated to implement?

Keeping dictionary up to date - it's a most difficult part here. Configuration
of dictionary might be done by ALTER command - so, parent process (and all
currently running backends) should get that information to reload dictionary.

> As for my second question, is it possible to use functions in tsearch2?
> For example, writing my own stemmer in PL/pgSQL or in C as a postgres
> function.

Yes, of course, you can develop your dictionary (-ies) and parser. Dut only in
C, because they are critical for performance.
--
Teodor Sigaev E-mail: teodor(at)sigaev(dot)ru
WWW: http://www.sigaev.ru/