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

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От Teodor Sigaev
Тема Re: tsearch2 on-demand dictionary loading & using functions in tsearch2
Дата
Msg-id 48304745.6090606@sigaev.ru
обсуждение исходный текст
Ответ на tsearch2 on-demand dictionary loading & using functions in tsearch2  (iSteve <isteve@bofh.cz>)
Ответы Re: tsearch2 on-demand dictionary loading & using functions in tsearch2
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> Hmm, good point; I presume "accept the fact that settings change won't
> propagate to other backends until reconnect" would not be acceptable
> behavior, even if documented along with the relevant configuration option?

I suppose so. That was one of the reasons to move tsearch into core and it will
be too regrettable to lost that feature again.

>>> 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.
> I've had something different in mind. Considering there are already
> facilities to use functions, be it PL/pgSQL, PL/Python or C, why not
> just use those with the condition that the function must accept
> some-arguments and return some-result? Or would using this, even while
> using C as the language used for the actual parser, slow things down too?

API to dictionary and parser intentionally utilizes complex (and nested)
C-structures to decrease overheads. During parse of text postgres makes two call
of parser (one call - parser returns word, second - word delimiter. Space is a
lexeme too! Although it's not a subject to index) and one call of dictionary per
word. So, if your language can work with C-structures then you can use that
language with tsearch with more or less performance pay. PL/pgSQL hasn't this
capability.

--
Teodor Sigaev                                   E-mail: teodor@sigaev.ru
                                                    WWW: http://www.sigaev.ru/

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