Обсуждение: tsearch partial word

On Mon, 2006-04-17 at 14:48 -0500, Yudie Pg wrote:
> Is it possible to search partial word as like '%...%' in tsearch?

Well at that point you are just going to seqscan anyway... so why not
just to a standard like search?

The could see that you might get a benefit from using the '%...%' on the
vectors columns though, as you may be scanning less data.

Joshua D. Drake


>
> Yudie
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Tsearch doesn't support such scan. You can add your own operation or modify
existing, but in any case index will not support it.

I don't known efficient index structure for queries you need...

Yudie Pg wrote:
> Is it possible to search partial word as *like '%...%'* in tsearch?
>
> Yudie

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

On 17.04.2006 21:48, Yudie Pg wrote:
> Is it possible to search partial word as *like '%...%'* in tsearch?

You can create a table with all the unique lexems (see pg_trgm doc on
how to do that) use LIKE %<whatever>% on it, join the matching lexems
with | in your ts_query..

It works ok as long as the count of returned lexems is low.. at some
point a seq scan would be faster again, so you might want to add a
threshold to fall back to that..


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Hannes Dorbath