Re: Tsearch2 performance on big database - Mailing list pgsql-performance

On Wed, 23 Mar 2005, Rick Jansen wrote:

> Oleg Bartunov wrote:
>> On Tue, 22 Mar 2005, Rick Jansen wrote:
>>
>> Hmm, default configuration is too eager, you index every lexem using simple
>> dictionary) ! Probably, it's too much. Here is what I have for my russian
>> configuration in dictionary database:
>>
>>  default_russian | lword        | {en_ispell,en_stem}
>>  default_russian | lpart_hword  | {en_ispell,en_stem}
>>  default_russian | lhword       | {en_ispell,en_stem}
>>  default_russian | nlword       | {ru_ispell,ru_stem}
>>  default_russian | nlpart_hword | {ru_ispell,ru_stem}
>>  default_russian | nlhword      | {ru_ispell,ru_stem}
>>
>> Notice, I index only russian and english words, no numbers, url, etc.
>> You may just delete unwanted rows in pg_ts_cfgmap for your configuration,
>> but I'd recommend just update them setting dict_name to NULL.
>> For example, to not indexing integers:
>>
>> update pg_ts_cfgmap set dict_name=NULL where ts_name='default_russian' and
>> tok_alias='int';
>>
>> voc=# select token,dict_name,tok_type,tsvector from ts_debug('Do you have
>> +70000 bucks');
>>  token  |      dict_name      | tok_type | tsvector
>> --------+---------------------+----------+----------
>>  Do     | {en_ispell,en_stem} | lword    |
>>  you    | {en_ispell,en_stem} | lword    |
>>  have   | {en_ispell,en_stem} | lword    |
>>  +70000 |                     | int      |
>>  bucks  | {en_ispell,en_stem} | lword    | 'buck'
>>
>> Only 'bucks' gets indexed :)
>> Hmm, probably I should add this into documentation.
>>
>> What about word statistics (# of unique words, for example).
>>
>
> I'm now following the guide to add the ispell dictionary and I've updated
> most of the rows setting dict_name to NULL:
>
>     ts_name     |  tok_alias   | dict_name
> -----------------+--------------+-----------
> default         | lword        | {en_stem}
> default         | nlword       | {simple}
> default         | word         | {simple}
> default         | part_hword   | {simple}
> default         | nlpart_hword | {simple}
> default         | lpart_hword  | {en_stem}
> default         | hword        | {simple}
> default         | lhword       | {en_stem}
> default         | nlhword      | {simple}
>
> These are left, but I have no idea what a 'hword' or 'nlhword' or any other
> of these tokens are.

from my notes http://www.sai.msu.su/~megera/oddmuse/index.cgi/Tsearch_V2_Notes
  I've asked how to know token types supported by parser. Actually, there is function token_type(parser), so you just
use:

     select * from token_type();

>
> Anyway, how do I find out the number of unique words or other word
> statistics?


from my notes http://www.sai.msu.su/~megera/oddmuse/index.cgi/Tsearch_V2_Notes

It's usefull to see words statistics, for example, to check how good your
dictionaries work or how did you configure pg_ts_cfgmap. Also, you may notice
probable stop words relevant for your collection.
Tsearch provides stat() function:

.......................

Don't hesitate to read it and if you find some bugs or know better wording
I'd be glad to improve my notes.

>
> Rick
>

     Regards,
         Oleg
_____________________________________________________________
Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
Sternberg Astronomical Institute, Moscow University (Russia)
Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
phone: +007(095)939-16-83, +007(095)939-23-83