Re: Term positions in GIN fulltext index

On Thu, Nov 3, 2011 at 11:01 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> Yoann Moreau <yoann(dot)moreau(at)univ-avignon(dot)fr> writes:
> > I'm using a GIN index for a text column on a big table. I use it to rank
> > the rows, but I also need to get the term positions for each document of
> a
> > subset of documents for one or more terms. I suppose these positions are
> stored
> > in the index as the to_tsvector shows them : 'lexeme':{positions}
>
> I'm pretty sure that a GIN index on tsvector does *not* store positions
> --- it only knows about the strings. Don't know one way or the other
> about GIST.
>
GiST index doesn't store positions too. See gtsvector_compress. It converts
tsvector to array of crc32 of words. If that value is anyway too large then
function converts it to signature.

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With best regards,
Alexander Korotkov.