| From: | "Pierre C" <lists(at)peufeu(dot)com> |
|---|---|
| To: | "pgsql-performance(at)postgresql(dot)org" <pgsql-performance(at)postgresql(dot)org>, "Neil Whelchel" <neil(dot)whelchel(at)gmail(dot)com> |
| Subject: | Re: Slow count(*) again... |
| Date: | 2010-10-12 21:35:01 |
| Message-ID: | op.vkhfkn1yeorkce@apollo13 |
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| Lists: | pgsql-hackers pgsql-performance |
> suggest that 99% instances of the "select count(*)" idiom are probably
>> bad use of the SQL language.
Well, suppose you paginate results. If the user sees that the search query
returns 500 pages, there are two options :
- you're google, and your sorting algorithms are so good that the answer
the user wants is in the first page
- or the user will refine his search by entering more keywords tu get a
manageable result set
So, in both cases, the count(*) was useless anyway. And the slowest ones
are the most useless, since the user will immediatey discard the result
and refine his query.
If your full text search is slow, try Xapian or Lucene.
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