Re: [BUGS] BUG #3975: tsearch2 index should not bomb out of 1Mb limit - Mailing list pgsql-patches

From Bruce Momjian
Subject Re: [BUGS] BUG #3975: tsearch2 index should not bomb out of 1Mb limit
Date
Msg-id 200803071322.m27DMv101933@momjian.us
Whole thread Raw
In response to Re: [BUGS] BUG #3975: tsearch2 index should not bomb out of 1Mb limit  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: [BUGS] BUG #3975: tsearch2 index should not bomb out of 1Mb limit  (Teodor Sigaev <teodor@sigaev.ru>)
List pgsql-patches
Tom Lane wrote:
> Bruce Momjian <bruce@momjian.us> writes:
> > Tom Lane wrote:
> >> I don't think that follows.  A tsearch index is lossy anyway, so there's
>
> > Uh, the index is lossy but I thought it was lossy in a way that just
> > required additional heap accesses, not lossy in that it doesn't index
> > everything.
>
> Sure it's lossy.  It doesn't index stopwords, and it doesn't index the
> difference between various forms of a word (when the dictionaries reduce
> them to a common root).

Yes, but you specify the stop words and stemming rules --- it isn't like
it drops words that are out of your control.

> > I am concerned a 1mb limit is too low though.  Exactly why can't we have
> > a higher limit?  Is positional information that significant?
>
> That's pretty much exactly the point: it's not very significant, and it
> doesn't justify a total inability to index large documents.

Agreed.  I think losing positional information after 1mb is acceptable.

> One thing we could do is index words that are past the limit but not
> store a position, or perhaps have the convention that the maximum
> position value means "somewhere past here".

Sure.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://postgres.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +

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