Re: Why is there a tsquery data type?

On Thu, 30 Aug 2007, Bruce Momjian wrote:

> Gregory Stark wrote:
>> "Bruce Momjian" <bruce@momjian.us> writes:
>>
>>> There is no question things would be clearer with only one text search
>>> data type.  The only value I can see to having a tsquery data type is
>>> that you can store a tsquery value in a column, but why would that be
>>> much better than just storing it in a TEXT field?
>>
>> When you try storing a tsquery in a column does it alert you if you have an
>> invalid syntax at that point? Storing it as text would mean not finding out
>> until you try to use the query.
>
> Yes it does check syntax:
>
>     test=> select 'lkjadsf kjfdsa'::tsquery;
>     ERROR:  syntax error in tsearch query: "lkjadsf kjfdsa"
>
> A larger question is how many people store queries in the database to
> make it worth the complexity.

you forget about very powerfull query rewriting, which is table driven

>
>> Is converting a text query into the internal format faster or less memory
>> intensive than converting text into the internal representation? When you run
>> a query like "WHERE '...' @@ col" if there wasn't a tsquery data type then
>> '...' would have to be parsed over and over again for each row.
>
> No, internally the TEXT string would be converted to something the
> system could deal with for that query, which is probably what 99% of all
> queries are going to do anyway by calling to_tsquery().
>
>
    Regards,        Oleg
_____________________________________________________________
Oleg Bartunov, Research Scientist, Head of AstroNet (www.astronet.ru),
Sternberg Astronomical Institute, Moscow University, Russia
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(495)939-16-83, +007(495)939-23-83