Tsearch not searching 'Y'

On Thu, Apr 29, 2010 at 01:13:40PM -0000, sandeep prakash dhumale wrote:

Hello All,

I am trying to get tsearch working for my application but I am facing a
problem when alphabet 'Y' is the in the tsquery.

can anyone please share some light on it.

# SELECT 'hollywood'::tsvector @@ to_tsquery('holly:*');
?column?
----------
f
(1 row)

SELECT 'hollywood'::tsvector @@ to_tsquery('holl:*');
?column?
----------
t
(1 row)

It works when i put <> in y as below but i don't want to do it that way.

SELECT 'hollywood'::tsvector @@ to_tsquery('holl<y>:*');
?column?
----------
t

Thanks in advance

That is because the to_tsquery() normalizes the tokens. Here is
what I get from the default configuration:

db=# select to_tsquery('holly:*');
to_tsquery
------------
'holli':*
(1 row)

db=# select to_tsquery('holl:*');
to_tsquery
------------
'holl':*
(1 row)

It is pretty easy to see why you see the behavior that you do.
Maybe you need to change your tsearch configuration to match what
you expect to happen.

Regards,
Ken

"sandeep prakash dhumale" <sandy9940@rediffmail.com> writes:

I am trying to get tsearch working for my application but I am facing a
problem when alphabet 'Y' is the in the tsquery.

# SELECT 'hollywood'::tsvector @@ to_tsquery('holly:*');
?column?
----------
f
(1 row)

You can't use to_tsquery for this sort of thing, because it tries to
normalize the given words:

regression=# select to_tsquery('holly:*');
to_tsquery
------------
'holli':*
(1 row)

If you do this it works:

regression=# SELECT 'hollywood'::tsvector @@ 'holly:*'::tsquery;
?column?
----------
t
(1 row)

So if you want to use prefix matching, don't normalize.

regards, tom lane

On Thu, 29 Apr 2010 19:27:33 +0530 wrote
&gt;On Thu, Apr 29, 2010 at 01:13:40PM -0000, sandeep prakash dhumale wrote:
&gt;&gt; Hello All,
&gt;&gt;
&gt;&gt; I am trying to get tsearch working for my application but I am facing a
&gt;&gt; problem when alphabet 'Y' is the in the tsquery.
&gt;&gt;
&gt;&gt; can anyone please share some light on it.
&gt;&gt;
&gt;&gt;
&gt;&gt; # SELECT 'hollywood'::tsvector @@ to_tsquery('holly:*');
&gt;&gt; ?column?
&gt;&gt; ----------
&gt;&gt; f
&gt;&gt; (1 row)
&gt;&gt;
&gt;&gt; SELECT 'hollywood'::tsvector @@ to_tsquery('holl:*');
&gt;&gt; ?column?
&gt;&gt; ----------
&gt;&gt; t
&gt;&gt; (1 row)
&gt;&gt;
&gt;&gt;
&gt;&gt; It works when i put &lt;&gt; in y as below but i don't want to do it that way.
&gt;&gt;
&gt;&gt; SELECT 'hollywood'::tsvector @@ to_tsquery('holl&lt;y&gt;:*');
&gt;&gt; ?column?
&gt;&gt; ----------
&gt;&gt; t
&gt;&gt;
&gt;&gt; Thanks in advance
&gt;
&gt;That is because the to_tsquery() normalizes the tokens. Here is
&gt;what I get from the default configuration:
&gt;
&gt;db=# select to_tsquery('holly:*');
&gt; to_tsquery
&gt;------------
&gt; 'holli':*
&gt;(1 row)
&gt;
&gt;db=# select to_tsquery('holl:*');
&gt; to_tsquery
&gt;------------
&gt; 'holl':*
&gt;(1 row)
&gt;
&gt;It is pretty easy to see why you see the behavior that you do.
&gt;Maybe you need to change your tsearch configuration to match what
&gt;you expect to happen.
&gt;
&gt;Regards,
&gt;Ken
&gt;
&gt;
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&gt;Sent via pgsql-general mailing list (pgsql-general@postgresql.org)
&gt;To make changes to your subscription:
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&gt;

First of all thanks for your replies Tom and Ken,

I am little newbie to Tsearch so I appologies if I sound a little confuse.

Tom: If i do by casting like you wrote then i ran into case sensitivity issue also then it does not work for other searches I guess then it sees for exact matches and not normalize to lexims.

Ken: As you said I need to change my configuration, It would be great if you can point me out where i can change that configuration

and what about that&nbsp; &lt;y&gt; in the query how does it work, does that mean to explicitly include y in to_tsquery.

All your help is higly appriciated.

--Sandy

You can avoid stemming by using 'simple' instead of 'english' as the
language of the words in to_tsvector (which is a little more awkward
than the cast).

"There are no stop words for the simple dictionary. It will just
convert to lower case, and index every unique word.
SELECT to_tsvector('simple', 'Andy andy The the in out');
to_tsvector
-------------------------------------
'in':5 'out':6 'the':3,4 'andy':1,2
(1 row)

John

On Apr 29, 2010, at 4:01 PM, Tom Lane wrote: